{"id":601,"date":"2021-12-17T21:49:13","date_gmt":"2021-12-17T21:49:13","guid":{"rendered":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/8-earth-history\/"},"modified":"2022-05-18T14:11:27","modified_gmt":"2022-05-18T14:11:27","slug":"8-earth-history","status":"publish","type":"chapter","link":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/8-earth-history\/","title":{"raw":"8 Earth History","rendered":"8 Earth History"},"content":{"raw":"[caption id=\"attachment_3273\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CdC1-scaled.jpg\"><img class=\"wp-image-3273 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/CdC1-scaled-1.jpg\" alt=\"The rock is a 750' spire.\" width=\"1024\" height=\"683\"><\/a> Spider Rock, within Canyon de Chelly National Monument, not only has a long human history with the Din\u00e9 tribe, but also has a long geologic history. The rocks are Permian in age, and formed in the desert conditions that dominated North America toward the end of the Paleozoic through the middle Mesozoic. Erosion of the canyon occurred in the Cenozoic.[\/caption]\n\n<strong>KEY CONCEPTS<\/strong>\n\n<strong>By the end of this chapter, students should be able to:<\/strong>\n<ul>\n \t<li>Explain the big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary] and origin of the [pb_glossary id=\"1778\"]elements[\/pb_glossary]<\/li>\n \t<li>Explain the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]\u2019s origin and the consequences for Earth.<\/li>\n \t<li>Describe the turbulent beginning of Earth during the [pb_glossary id=\"1255\"]Hadean[\/pb_glossary] and [pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eons[\/pb_glossary]<\/li>\n \t<li>Identify the transition to modern [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary], [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary], and evolution that occurred in the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]<\/li>\n \t<li>Describe the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] evolution and [pb_glossary id=\"755\"]extinction[\/pb_glossary] of invertebrates with hard parts, fish, amphibians, reptiles, tetrapods, and land plants; and [pb_glossary id=\"1654\"]tectonics[\/pb_glossary] and sedimentation associated with the [pb_glossary id=\"1701\"]supercontinent[\/pb_glossary] [pb_glossary id=\"2444\"]Pangea[\/pb_glossary]<\/li>\n \t<li>Describe the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] evolution and [pb_glossary id=\"755\"]extinction[\/pb_glossary] of birds, dinosaurs, and mammmals; and [pb_glossary id=\"1654\"]tectonics[\/pb_glossary] and sedimentation associated with the breakup of [pb_glossary id=\"2444\"]Pangea[\/pb_glossary]<\/li>\n \t<li>Describe the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] evolution of mammals and birds, paleoclimate, and [pb_glossary id=\"1654\"]tectonics[\/pb_glossary] that shaped the modern world<\/li>\n<\/ul>\n&nbsp;\n\n[caption id=\"attachment_2486\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/GeologicClock.png\"><img class=\"wp-image-52 size-medium\" title=\"By WoudloperDerivative work: Hardwigg (File:Geologic_clock.jpg) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AGeologic_Clock_with_events_and_periods.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/GeologicClock-300x288.png\" alt=\"The circle starts at 4.6 billion years ago, then loops around to zero.\" width=\"300\" height=\"288\"><\/a> Geologic time on Earth, represented circularly, to show the individual time divisions and important events. Ga=billion years ago, Ma=million years ago.[\/caption]Entire courses and careers have been based on the wide-ranging topics covering Earth\u2019s history. Throughout the long history of Earth, change has been the norm. Looking back in time, an untrained eye would see many unfamiliar life forms and terrains. The main topics studied in Earth history are paleogeography, paleontology, and paleoecology and paleoclimatology\u2014respectively, past landscapes, past organisms, past ecosystems, and past environments. This chapter will cover briefly the origin of the universe and the 4.6 billion year history of Earth. This Earth history will [pb_glossary id=\"2158\"]focus[\/pb_glossary] on the major physical and biological events in each [pb_glossary id=\"1242\"]Eons[\/pb_glossary] and [pb_glossary id=\"1243\"]Era[\/pb_glossary].\n<h2><strong>8.1 Origin of the Universe<\/strong><\/h2>\n[caption id=\"attachment_3275\" align=\"alignright\" width=\"349\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/HubbleDeepField.jpg\"><img class=\"wp-image-519\" title=\"NASA, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-300x294.jpg\" alt=\"The picture has over 1500 galaxies.\" width=\"349\" height=\"342\"><\/a> The Hubble Deep Field. This image, released in 1996, is a composite long-exposure picture of one of the darkest parts of the night sky. Every light on this image that does not have diffraction spikes is believed to be an entire galaxy, with hundreds of billions of stars, demonstrating the immense size and scope of the universe.[\/caption]\n\nThe universe appears to have an infinite number of galaxies and solar systems and our [pb_glossary id=\"1253\"]solar system[\/pb_glossary] occupies a small section of this vast entirety. The origins of the universe and [pb_glossary id=\"1253\"]solar system[\/pb_glossary] set the context for conceptualizing the Earth\u2019s origin and early history.\n<h3><b>8.1.1 Big-Bang Theory<\/b><\/h3>\n[caption id=\"attachment_3276\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/UniverseTimeline.jpg\"><img class=\"wp-image-520 size-medium\" title=\"By NASA\/WMAP Science Team (Original version: NASA; modified by Ryan Kaldari) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ACMB_Timeline300_no_WMAP.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/UniverseTimeline-300x195.jpg\" alt=\"It starts small, then explodes outward\" width=\"300\" height=\"195\"><\/a> Timeline of expansion of the Universe[\/caption]<span style=\"font-weight: 400\">The mysterious details of events prior to and during the origin of the universe are subject to great scientific debate. The prevailing idea about how the universe was created is called the <strong>big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary]<\/strong>. Although the ideas behind the big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary] feel almost mystical, they are supported by Einstein\u2019s [pb_glossary id=\"1733\"]theory[\/pb_glossary] of general relativity. Other scientific evidence, grounded in empirical observations, supports the big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary].<\/span>\n\n<span style=\"font-weight: 400\">The big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary] proposes the universe was formed from an infinitely dense and hot [pb_glossary id=\"1667\"]core[\/pb_glossary] of material. The bang in the title suggests there was an explosive, outward expansion of all matter and space that created atoms. [pb_glossary id=\"1719\"]Spectroscopy[\/pb_glossary] confirms that hydrogen makes up about 74% of all matter in the universe. Since its creation, the universe has been expanding for 13.8 billion years and recent observations suggest the rate of this expansion is increasing<\/span><span style=\"font-weight: 400\">.\u00a0<\/span>\n<h4><span style=\"font-weight: 400\">Spectroscopy<\/span><\/h4>\n[caption id=\"attachment_3277\" align=\"alignright\" width=\"383\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/EM_Spectrum_Properties_edit.svg_.png\"><img class=\"wp-image-521\" title=\"By Inductiveload, NASA [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEM_Spectrum_Properties_edit.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/EM_Spectrum_Properties_edit.svg_-300x178.png\" alt=\"The figure shows the various wavelengths of electromagnetic light, the scale of the wavelength, the frequency, and the temperature of objects that produces waves.\" width=\"383\" height=\"227\"><\/a> The electromagnetic spectrum and properties of light across the spectrum.[\/caption]<span style=\"font-weight: 400\"><strong>[pb_glossary id=\"1719\"]Spectroscopy[\/pb_glossary]<\/strong> is the investigation and measurement of spectra produced when materials interacts with or emits electromagnetic radiation. <em>Spectra<\/em> is the plural for <em>spectrum<\/em> which is a particular [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] from the <strong>[pb_glossary id=\"1720\"]electromagnetic spectrum[\/pb_glossary]<\/strong>. Common spectra include the different colors of visible light, X-rays, ultraviolet waves, microwaves, and radio waves. Each beam of light is a unique mixture of wavelengths that combine across the spectrum to make the color we see. The light wavelengths are created or absorbed inside atoms, and each [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] signature matches a specific [pb_glossary id=\"1778\"]element[\/pb_glossary]. Even white light from the Sun, which seems like an uninterrupted continuum of wavelengths, has gaps in some wavelengths. The gaps correspond to [pb_glossary id=\"1778\"]elements[\/pb_glossary] present in the Earth\u2019s [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] that act as filters for specific wavelengths. These missing wavelengths were famously observed by Joseph von Fraunhofer (1787\u20131826) in the early 1800s<\/span><span style=\"font-weight: 400\">, but it took decades before scientists were able to relate the missing wavelengths to atmospheric filtering<\/span><span style=\"font-weight: 400\">. <\/span>[pb_glossary id=\"1719\"]Spectroscopy[\/pb_glossary] shows that the Sun is mostly made of hydrogen and helium. Applying this process to light from distant stars, scientists can calculate the abundance of [pb_glossary id=\"1778\"]elements[\/pb_glossary] in a specific star and visible universe as a whole. Also, this spectroscopic information can be used as an interstellar speedometer.\n<h4><span style=\"font-weight: 400\">Redshift<\/span><\/h4>\n[caption id=\"attachment_3278\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dopplerfrequenz.gif\"><img class=\"wp-image-522 size-medium\" title=\"By Charly Whisky 18:20, 27 January 2007 (yyy) (Own work) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>, <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.5-2.0-1.0&quot;>CC BY-SA 2.5-2.0-1.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADopplerfrequenz.gif&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dopplerfrequenz-300x75.gif\" alt=\"In this animated image, the car moves, and the waves are pushed in the front, and stretched behind it.\" width=\"300\" height=\"75\"><\/a> The Doppler effect is heard as a car moves. The waves in front of the car are compressed together, making the pitch higher. The waves in the back of the car are stretched, and and the pitch gets lower.[\/caption]<span style=\"font-weight: 400\">The <strong>[pb_glossary id=\"1721\"]Doppler effect[\/pb_glossary]<\/strong> is the same process that changes the pitch of the sound of an approaching car or ambulance from high to low as it passes. When an object emits waves, such as light or sound, while moving toward an observer, the wavelengths get compressed. In sound, this results in a shift to a higher pitch. When an object moves away from an observer, the wavelengths are extended, producing a lower pitched sound. The [pb_glossary id=\"1721\"]Doppler effect[\/pb_glossary] is used on light emitted from stars and galaxies to determine their speed and direction of travel<\/span><span style=\"font-weight: 400\">. Scientists, including Vesto Slipher (1875\u20131969)<\/span><span style=\"font-weight: 400\"> and Edwin Hubble (1889\u20131953)<\/span><span style=\"font-weight: 400\">, examined galaxies both near and far and found that almost all galaxies outside of our galaxy are moving away from each other, and us. Because the light wavelengths of receding objects are extended, visible light is shifted toward the red end of the spectrum, called a <strong>[pb_glossary id=\"1247\"]redshift[\/pb_glossary]<\/strong>. In addition, Hubble noticed that galaxies that were farther away from Earth also had the greater amount of [pb_glossary id=\"1247\"]redshift[\/pb_glossary], and thus, the faster they are traveling away from us. The only way to reconcile this information is to deduce the universe is still expanding. Hubble\u2019s [pb_glossary id=\"1729\"]observation[\/pb_glossary] forms the basis of big-bang [pb_glossary id=\"1733\"]theory[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_4252\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Example-of-Doppler-Shift-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-523\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/a3RfULw7aAY[\/embed]\n<h4><span style=\"font-weight: 400\">Cosmic Microwave Background Radiation<\/span><\/h4>\n[caption id=\"attachment_3279\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CosmicBackground.png\"><img class=\"wp-image-524 size-medium\" title=\"By NASA \/ WMAP Science Team [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AIlc_9yr_moll4096.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CosmicBackground-300x150.png\" alt=\"The map is blue with slight bright spots of green\/yellow\" width=\"300\" height=\"150\"><\/a> Heat map, showing slight variations in background heat, which is related to cosmic background radiation.[\/caption]<span style=\"font-weight: 400\">Another strong indication of the big-bang is <strong>[pb_glossary id=\"1248\"]cosmic microwave background radiation[\/pb_glossary]<\/strong>. Cosmic radiation was accidentally discovered by Arno Penzias (1933\u2013) and Robert Woodrow Wilson (1936\u2013) <\/span>when they were trying to eliminate background noise from a communication satellite. They discovered very faint traces of energy or heat that are omnipresent across the universe. This energy was left behind from the [pb_glossary id=\"1246\"]big bang[\/pb_glossary], like an echo.\n<h3><b>8.1.2 Stellar Evolution<\/b><\/h3>\n[caption id=\"attachment_3280\" align=\"alignleft\" width=\"400\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Nucleosynthesis_periodic_table.svg_-1.png\"><img class=\"wp-image-525\" title=\"By Cmglee (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a> or <a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ANucleosynthesis_periodic_table.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Nucleosynthesis_periodic_table.svg_-1-300x150.png\" alt=\"This shows the period table. Some elements are made in the big bang, some are made in stellar processes.\" width=\"400\" height=\"200\"><\/a> Origin of the elements on the periodic table, showing the important role the star life cycle plays.[\/caption]Astronomers think the [pb_glossary id=\"1246\"]big bang[\/pb_glossary] created lighter [pb_glossary id=\"1778\"]elements[\/pb_glossary], mostly hydrogen and smaller amounts of [pb_glossary id=\"1778\"]elements[\/pb_glossary] helium, lithium, and beryllium. Another process must be responsible for creating the other 90 heavier [pb_glossary id=\"1778\"]elements[\/pb_glossary]. The current model of stellar evolution explains the origins of these heavier [pb_glossary id=\"1778\"]elements[\/pb_glossary].\n<h4><span style=\"font-weight: 400\">Birth of a star<\/span><\/h4>\n[caption id=\"attachment_3281\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Eagle_nebula_pillars.jpg\"><img class=\"wp-image-526 size-medium\" title=\"By Credit: NASA, Jeff Hester, and Paul Scowen (Arizona State University) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEagle_nebula_pillars.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Eagle_nebula_pillars-300x296.jpg\" alt=\"It is several large column of gas\" width=\"300\" height=\"296\"><\/a> Section of the Eagle Nebula known as \"The Pillars of Creation.\"[\/caption]Stars start their lives as [pb_glossary id=\"1778\"]elements[\/pb_glossary] floating in cold, spinning clouds of gas and dust known as <strong>[pb_glossary id=\"1249\"]nebulas[\/pb_glossary]<\/strong>. Gravitational attraction or perhaps a nearby stellar explosion causes the [pb_glossary id=\"1778\"]elements[\/pb_glossary] to condense and spin into disk shape. In the center of this disk shape a new star is born under the force of gravity. The spinning whirlpool concentrates material in the center, and the increasing gravitational forces collect even more mass. Eventually, the immensely [pb_glossary id=\"2411\"]concentrated[\/pb_glossary] mass of material reaches a critical point of such intense heat and pressure it initiates [pb_glossary id=\"1250\"]fusion[\/pb_glossary].\n<h4><span style=\"font-weight: 400\">Fusion<\/span><\/h4>\n[caption id=\"attachment_3282\" align=\"alignleft\" width=\"211\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/FusionintheSun.svg_.png\"><img class=\"wp-image-527 size-medium\" title=\"<a href=&quot;Borb&quot; title=&quot;User:Borb&quot;>Borb<\/a> [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFusionintheSun.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FusionintheSun.svg_-211x300.png\" alt=\"There are 3 steps\" width=\"211\" height=\"300\"><\/a> General diagram showing the series of fusion steps that occur in the sun.[\/caption][pb_glossary id=\"1250\"]Fusion[\/pb_glossary] is not a chemical reaction. <strong>[pb_glossary id=\"1250\"]Fusion[\/pb_glossary]<\/strong> is a nuclear reaction in which two or more nuclei, the centers of atoms, are forced together and combine creating a new larger atom. This reaction gives off a tremendous amount of energy, usually as light and solar radiation. An [pb_glossary id=\"1778\"]element[\/pb_glossary] such as hydrogen combines or fuses with other hydrogen atoms in the [pb_glossary id=\"1667\"]core[\/pb_glossary] of a star to become a new [pb_glossary id=\"1778\"]element[\/pb_glossary], in this case, helium. Another product of this process is energy, such as solar radiation that leaves the Sun and comes to the Earth as light and heat. [pb_glossary id=\"1250\"]Fusion[\/pb_glossary] is a steady and predictable process, which is why we call this the main phase of a star\u2019s life. During its main phase, a star turns hydrogen into helium. Since most stars contain plentiful amounts of hydrogen, the main phase may last billions of years, during which their size and energy output remains relatively steady.\n\n[caption id=\"attachment_3283\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Star_life_cycles_red_dwarf_en.svg_.png\"><img class=\"wp-image-528 size-medium\" title=\"By cmglee, NASA Goddard Space Flight Center (File:star_life_cycles_red_dwarf.jpg) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStar_life_cycles_red_dwarf_en.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Star_life_cycles_red_dwarf_en.svg_-300x200.png\" alt=\"It shows many steps\" width=\"300\" height=\"200\"><\/a> Two main paths of a star's life cycle, depending on mass.[\/caption]The giant phase in a star\u2019s life occurs when the star runs out of hydrogen for [pb_glossary id=\"1250\"]fusion[\/pb_glossary]. If a star is large enough, it has sufficient heat and pressure to start fusing helium into heavier [pb_glossary id=\"1778\"]elements[\/pb_glossary]. This style of [pb_glossary id=\"1250\"]fusion[\/pb_glossary] is more energetic and the higher energy and [pb_glossary id=\"1767\"]temperature[\/pb_glossary] expand the star to a larger size and brightness. This giant phase is predicted to happen to our Sun in another few billion years, growing the radius of the Sun to Earth\u2019s orbit, which will render life impossible. The mass of a star during its main phase is the primary factor in determining how it will evolve. If the star has enough mass and reaches a point at which the primary [pb_glossary id=\"1250\"]fusion[\/pb_glossary] [pb_glossary id=\"1778\"]element[\/pb_glossary], such as helium, is exhausted, [pb_glossary id=\"1250\"]fusion[\/pb_glossary] continues using new, heavier [pb_glossary id=\"1778\"]elements[\/pb_glossary]. This occurs over and over in very large stars, forming progressively heavier [pb_glossary id=\"1778\"]elements[\/pb_glossary] like carbon and oxygen. Eventually, [pb_glossary id=\"1250\"]fusion[\/pb_glossary] reaches its limit as it forms iron and nickel. This progression explains the abundance of iron and nickel in rocky objects, like Earth, within the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]. At this point, any further [pb_glossary id=\"1250\"]fusion[\/pb_glossary] absorbs energy instead of giving it off, which is the beginning of the end of the star\u2019s life<span style=\"font-weight: 400\">.<\/span>\n<h4><span style=\"font-weight: 400\">Death of a Star<\/span><\/h4>\n[caption id=\"attachment_3284\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Crab_Nebula.jpg\"><img class=\"wp-image-529 size-medium\" title=\"NASA and ESA image, public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-300x300.jpg\" alt=\"The picture is of dust and gas.\" width=\"300\" height=\"300\"><\/a> Hubble space telescope image of the Crab Nebula, the remnants of a supernova that occurred in 1054 C.E.[\/caption]\n\n<span style=\"font-weight: 400\">The death of a star can range from spectacular to other-worldly (see figure). Stars like the Sun form a planetary [pb_glossary id=\"1249\"]nebula[\/pb_glossary], which comes from the collapse of the star\u2019s outer layers in an event like the implosion of a building. In the tug-of-war between gravity\u2019s inward pull and [pb_glossary id=\"1250\"]fusion\u2019s[\/pb_glossary] outward push, gravity instantly takes over when [pb_glossary id=\"1250\"]fusion[\/pb_glossary] ends, with the outer gasses puffing away to form a [pb_glossary id=\"1249\"]nebula[\/pb_glossary]. More [pb_glossary id=\"985\"]massive[\/pb_glossary] stars do this as well but with a more energetic collapse, which starts another type of energy release mixed with [pb_glossary id=\"1778\"]element[\/pb_glossary] creation known as a [pb_glossary id=\"1251\"]supernova[\/pb_glossary]. In a <strong>[pb_glossary id=\"1251\"]supernova[\/pb_glossary]<\/strong>, the collapse of the [pb_glossary id=\"1667\"]core[\/pb_glossary] suddenly halts, creating a [pb_glossary id=\"985\"]massive[\/pb_glossary] outward-propagating shock wave. A [pb_glossary id=\"1251\"]supernova[\/pb_glossary] is the most energetic explosion in the universe short of the [pb_glossary id=\"1246\"]big bang[\/pb_glossary]. The energy release is so significant the ensuing [pb_glossary id=\"1250\"]fusion[\/pb_glossary] can make every [pb_glossary id=\"1778\"]element[\/pb_glossary] up through uranium<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3285\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/08.1_blackhole_NASA_2019.png\"><img class=\"wp-image-530 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-300x175.png\" alt=\"Blurry telescope photo of a fuzzy red halo around an entirely black center. The black center represents the first photograph of an actual black hole captured in 2019.\" width=\"300\" height=\"175\"><\/a> A black hole and its shadow have been captured in an image for the first time in 2019, a historic feat by an international network of radio telescopes called the Event Horizon Telescope (Source: NASA)[\/caption]\n\n<span style=\"font-weight: 400\">The death of the star can result in the creation of white dwarfs, neutron stars, or black holes. Following their deaths, stars like the Sun turn into white dwarfs<\/span><span style=\"font-weight: 400\">.<\/span>\n\nWhite dwarfs are hot star embers, formed by packing most of a dying star\u2019s mass into a small and dense object about the size of Earth. Larger stars may explode in a [pb_glossary id=\"1251\"]supernova[\/pb_glossary] that packs their mass even tighter to become neutron stars. Neutron stars are so dense that protons combine with electrons to form neutrons. The largest stars collapse their mass even further, becoming objects so dense that light cannot escape their gravitational grasp. These are the infamous black holes and the details of the physics of what occurs in them are still up for debate.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"48\"]\n\n[caption id=\"attachment_4240\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-531\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.1 via this QR Code.[\/caption]\n<h2><strong>8.2 Origin of the Solar System: The Nebular Hypothesis<\/strong><\/h2>\n[caption id=\"attachment_3286\" align=\"alignleft\" width=\"252\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/M42proplyds.jpg\"><img class=\"wp-image-532\" title=\"By C.R. O'Dell\/Rice University; NASA [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AM42proplyds.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/M42proplyds-300x224.jpg\" alt=\"It is a small cloud\" width=\"252\" height=\"188\"><\/a> Small protoplanetary discs in the Orion Nebula[\/caption]<span style=\"font-weight: 400\">Our [pb_glossary id=\"1253\"]solar system[\/pb_glossary] formed at the same time as our Sun as described in the [pb_glossary id=\"1252\"]nebular hypothesis[\/pb_glossary]. The <strong>[pb_glossary id=\"1252\"]nebular hypothesis[\/pb_glossary]<\/strong> is the idea that a spinning cloud of dust made of mostly light [pb_glossary id=\"1778\"]elements[\/pb_glossary], called a [pb_glossary id=\"1249\"]nebula[\/pb_glossary], flattened into a protoplanetary disk, and became a [pb_glossary id=\"1253\"]solar system[\/pb_glossary] consisting of a star with orbiting planets<\/span><span style=\"font-weight: 400\">. <\/span>The spinning [pb_glossary id=\"1249\"]nebula[\/pb_glossary] collected the vast majority of material in its center, which is why the sun Accounts for over 99% of the mass in our [pb_glossary id=\"1253\"]solar system[\/pb_glossary].\n\n&nbsp;\n<h3><b>8.2.1 Planet Arrangement and Segregation<\/b><\/h3>\n[caption id=\"attachment_3287\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fomalhaut_Circumstellar_Disk.jpg\"><img class=\"wp-image-533 size-medium\" title=\"By NASA\/JPL-Caltech\/K. Stapelfeldt (JPL), James Clerk Maxwell Telescope [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFomalhaut_Circumstellar_Disk.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fomalhaut_Circumstellar_Disk-300x240.jpg\" alt=\"The disc is lop sided\" width=\"300\" height=\"240\"><\/a> This disk is asymmetric, possibly because of a large gas giant planet orbiting relatively far from the star.[\/caption]<span style=\"font-weight: 400\">As our [pb_glossary id=\"1253\"]solar system[\/pb_glossary] formed, the nebular cloud of dispersed particles developed distinct [pb_glossary id=\"1767\"]temperature[\/pb_glossary] zones. Temperatures were very high close to the center, only allowing condensation of metals and [pb_glossary id=\"1787\"]silicate[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary] with high melting points. Farther from the Sun, the temperatures were lower, allowing the condensation of lighter gaseous molecules such as methane, ammonia, carbon dioxide, and water<\/span><span style=\"font-weight: 400\">. This [pb_glossary id=\"1767\"]temperature[\/pb_glossary] differentiation resulted in the inner four planets of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] becoming rocky, and the outer four planets becoming gas giants.<\/span>\n\n[caption id=\"attachment_3288\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/HL_Tau_protoplanetary_disk.jpg\"><img class=\"wp-image-534 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-300x300.jpg\" alt=\"The orange disk has zones that are darker, indicating the planets are growing by using that material in the disk.\" width=\"300\" height=\"300\"><\/a> Image by the ALMA telescope of HL Tauri and its protoplanetary disk, showing grooves formed as planets absorb material in the disk.[\/caption]\n\nBoth rocky and gaseous planets have a similar growth model. Particles of dust, floating in the disc were attracted to each other by static charges and eventually, gravity. As the clumps of dust became bigger, they interacted with each other\u2014colliding, sticking, and forming proto-planets. The planets continued to grow over the course of many thousands or millions of years, as material from the protoplanetary disc was added. Both rocky and gaseous planets started with a solid [pb_glossary id=\"1667\"]core[\/pb_glossary]. Rocky planets built more rock on that [pb_glossary id=\"1667\"]core[\/pb_glossary], while gas planets added gas and ice. Ice giants formed later and on the furthest edges of the disc, accumulating less gas and more ice. That is why the gas-giant planets Jupiter and Saturn are [pb_glossary id=\"1909\"]composed[\/pb_glossary] of mostly hydrogen and helium gas, more than 90%. The ice giants Uranus and Neptune are [pb_glossary id=\"1909\"]composed[\/pb_glossary] of mostly methane ices and only about 20% hydrogen and helium gases.\n\n[caption id=\"attachment_4330\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis.jpg\"><img class=\"wp-image-535 size-medium\" title=\"A. Angelich (NRAO\/AUI\/NSF)\/ALMA (ESO\/NAOJ\/NRAO)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-300x255.jpg\" alt=\"It shows a ring of ice around the star\" width=\"300\" height=\"255\"><\/a> This artist\u2019s impression of the water snowline around the young star V883 Orionis, as detected with ALMA.[\/caption]\n\n&nbsp;\n\nThe planetary [pb_glossary id=\"1909\"]composition[\/pb_glossary] of the gas giants is clearly different from the rocky planets. Their size is also dramatically different for two reasons: First, the original planetary [pb_glossary id=\"1249\"]nebula[\/pb_glossary] contained more gases and ices than metals and rocks. There was abundant hydrogen, carbon, oxygen, nitrogen, and less silicon and iron, giving the outer planets more building material. Second, the stronger gravitational pull of these giant planets allowed them to collect large quantities of hydrogen and helium, which could not be collected by weaker gravity of the smaller planets.\n\n[caption id=\"attachment_2515\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.2_TolucaMeteorite.jpg\"><img class=\"wp-image-83 size-medium\" title=\"By H. Raab (User:Vesta) (Own work) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ATolucaMeteorite.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.2_TolucaMeteorite-300x225.jpg\" alt=\"The meteorite is polished showing the Widmanst\u00e4tten Pattern.\" width=\"300\" height=\"225\"><\/a> A polished fragment of the iron-rich Toluca Meteorite, with octahedral Widmanst\u00e4tten Pattern.[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">Jupiter\u2019s [pb_glossary id=\"985\"]massive[\/pb_glossary] gravity further shaped the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] and growth of the inner rocky planets. As the [pb_glossary id=\"1249\"]nebula[\/pb_glossary] started to coalesce into planets, Jupiter\u2019s gravity accelerated the movement of nearby materials, generating destructive collisions rather than constructively gluing material together<\/span><span style=\"font-weight: 400\">. <\/span>These collisions created the asteroid belt, an unfinished planet, located between Mars and Jupiter. This asteroid belt is the source of most <strong>[pb_glossary id=\"1254\"]meteorites[\/pb_glossary]<\/strong> that currently impact the Earth. Study of asteroids and [pb_glossary id=\"1254\"]meteorites[\/pb_glossary] help geologist to determine the age of Earth and the [pb_glossary id=\"1909\"]composition[\/pb_glossary] of its [pb_glossary id=\"1667\"]core[\/pb_glossary], [pb_glossary id=\"1664\"]mantle[\/pb_glossary], and [pb_glossary id=\"1658\"]crust[\/pb_glossary]. Jupiter\u2019s gravity may also explain Mars\u2019 smaller mass, with the larger planet consuming material as it migrated from the inner to outer edge of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]<span style=\"font-weight: 400\">.\u00a0<\/span>\n<h4><span style=\"font-weight: 400\">Pluto and planet definition<\/span><\/h4>\n[caption id=\"attachment_3290\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/EightTNOs.png\"><img class=\"wp-image-536 size-medium\" title=\"By Lexicon [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>, <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.5-2.0-1.0&quot;>CC BY-SA 2.5-2.0-1.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEightTNOs.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/EightTNOs-300x218.png\" alt=\"It shows many objects\" width=\"300\" height=\"218\"><\/a> Eight largest objects discovered past Neptune.[\/caption]<span style=\"font-weight: 400\">The outermost part of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] is known as the Kuiper belt, which is a scattering of rocky and icy bodies. Beyond that is the Oort cloud, a zone filled with small and dispersed ice traces. These two locations are where most comets form and continue to orbit, and objects found here have relatively irregular orbits compared to the rest of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. <\/span>Pluto, formerly the ninth planet, is located in this region of space. The XXVIth General Assembly of the International Astronomical Union (IAU) stripped Pluto of planetary status in 2006 because scientists discovered an object more [pb_glossary id=\"985\"]massive[\/pb_glossary] than Pluto, which they named Eris. The IAU decided against including Eris as a planet, and therefore, excluded Pluto as well. The IAU narrowed the definition of a planet to three criteria: 1) enough mass to have gravitational forces that force it to be rounded, 2) not [pb_glossary id=\"985\"]massive[\/pb_glossary] enough to create [pb_glossary id=\"1250\"]fusion[\/pb_glossary], and 3) large enough to be in a cleared orbit, free of other planetesimals that should have been incorporated at the time the planet formed. Pluto passed the first two parts of the definition, but not the third. Pluto and Eris are currently classified as dwarf planets.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"49\"]\n\n[caption id=\"attachment_4241\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-537\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.2 via this QR Code.[\/caption]\n<h2><span style=\"font-size: 28px\">8.3 Hadean Eon<\/span><\/h2>\n[caption id=\"attachment_3270\" align=\"alignleft\" width=\"232\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/17.18_Geologic_Time_Scale_with_years-1.jpg\"><img class=\"wp-image-3270 size-medium\" title=\"Image by Belinda Madsen\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/17.18_Geologic_Time_Scale_with_years-1-1.jpg\" alt=\"The Geologic Time Scale with an age of each unit shown by a scale\" width=\"232\" height=\"300\"><\/a> Geologic Time Scale with ages shown[\/caption]\n\nGeoscientists use the geological time scale to assign relative age names to events and rocks, separating major events in Earth\u2019s history based on significant changes as recorded in rocks and [pb_glossary id=\"1228\"]fossils[\/pb_glossary]. This section summarizes the most notable events of each major time interval. For a breakdown on how these time intervals are chosen and organized, see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">chapter 7<\/a>.\n\n<span style=\"font-weight: 400\">The [pb_glossary id=\"1255\"]Hadean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary], named after the Greek god and ruler of the underworld Hades, is the oldest [pb_glossary id=\"1242\"]eon[\/pb_glossary] and dates from 4.5\u20134.0 billion years ago<\/span><span style=\"font-weight: 400\">. \u00a0<\/span>\n\n[caption id=\"attachment_3244\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hadean.png\"><img class=\"wp-image-491 size-medium\" title=\"By Tim Bertelink (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AHadean.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hadean-300x161.png\" alt=\"The surface of Earth is full of volcanoes.\" width=\"300\" height=\"161\"><\/a> Artist's impression of the Earth in the Hadean.[\/caption]<span style=\"font-weight: 400\">This time represents Earth\u2019s earliest history, during which the planet was characterized by a partially molten surface, [pb_glossary id=\"228\"]volcanism[\/pb_glossary], and asteroid impacts. Several mechanisms made the newly forming Earth incredibly hot: gravitational [pb_glossary id=\"493\"]compression[\/pb_glossary], [pb_glossary id=\"2044\"]radioactive[\/pb_glossary] decay, and asteroid impacts. Most of this initial heat still exists inside the Earth. The [pb_glossary id=\"1255\"]Hadean[\/pb_glossary] was originally defined as the birth of the planet occurring 4.0 billion years ago and preceding the existence of many rocks and life forms. However, geologists have dated [pb_glossary id=\"1765\"]minerals[\/pb_glossary] at 4.4 billion years, with evidence that liquid water was present<\/span><span style=\"font-weight: 400\">. <\/span><span style=\"font-weight: 400\"> There is possibly even evidence of life existing over 4.0 billion years ago<\/span><span style=\"font-weight: 400\">. However, the most reliable record for early life, the microfossil record, starts at 3.5 billion years ago<\/span><span style=\"font-weight: 400\">. <\/span>\n<h3><b>8.3.1 Origin of Earth's Crust<\/b><\/h3>\n[caption id=\"attachment_3291\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MohoDepth.png\"><img class=\"wp-image-539 size-medium\" title=\"By AllenMcC. (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AMohomap.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MohoDepth-300x167.png\" alt=\"Places with mountain building have a deeper moho.\" width=\"300\" height=\"167\"><\/a> The global map of the depth of the moho, or thickness of the crust.[\/caption]<span style=\"font-weight: 400\">As Earth cooled from its molten state, [pb_glossary id=\"1765\"]minerals[\/pb_glossary] started to crystallize and settle resulting in a separation of [pb_glossary id=\"1765\"]minerals[\/pb_glossary] based on density and the creation of the [pb_glossary id=\"1658\"]crust[\/pb_glossary], [pb_glossary id=\"1664\"]mantle[\/pb_glossary], and [pb_glossary id=\"1667\"]core[\/pb_glossary]. The earliest Earth was chiefly molten material and would have been rounded by gravitational forces so it resembled a ball of [pb_glossary id=\"1751\"]lava[\/pb_glossary] floating in space. As the outer part of the Earth slowly cooled, the high melting-point [pb_glossary id=\"1765\"]minerals[\/pb_glossary] (see [pb_glossary id=\"221\"]Bowen\u2019s Reaction Series[\/pb_glossary] in <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>) formed solid slabs of early [pb_glossary id=\"1658\"]crust[\/pb_glossary]. These slabs were probably unstable and easily reabsorbed into the liquid [pb_glossary id=\"1750\"]magma[\/pb_glossary] until the Earth cooled enough to allow numerous larger fragments to form a thin primitive [pb_glossary id=\"1658\"]crust[\/pb_glossary]. Scientists generally assume this [pb_glossary id=\"1658\"]crust[\/pb_glossary] was [pb_glossary id=\"1659\"]oceanic[\/pb_glossary] and [pb_glossary id=\"1008\"]mafic[\/pb_glossary] in [pb_glossary id=\"1909\"]composition[\/pb_glossary], and littered with impacts, much like the Moon\u2019s current [pb_glossary id=\"1658\"]crust[\/pb_glossary]. There is still some debate over when [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary] started, which would have led to the [pb_glossary id=\"2038\"]formation[\/pb_glossary] of [pb_glossary id=\"1653\"]continental[\/pb_glossary] and [pb_glossary id=\"1006\"]felsic[\/pb_glossary] [pb_glossary id=\"1658\"]crust[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Regardless of this, as Earth cooled and solidified, less dense [pb_glossary id=\"1006\"]felsic[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary] floated to the surface of the Earth to form the [pb_glossary id=\"1658\"]crust[\/pb_glossary], while the denser [pb_glossary id=\"1008\"]mafic[\/pb_glossary] and [pb_glossary id=\"1009\"]ultramafic[\/pb_glossary] materials sank to form the [pb_glossary id=\"1664\"]mantle[\/pb_glossary] and the highest-density iron and nickel sank into the [pb_glossary id=\"1667\"]core[\/pb_glossary]. This differentiated the Earth from a homogenous planet into a heterogeneous one with layers of [pb_glossary id=\"1006\"]felsic[\/pb_glossary] [pb_glossary id=\"1658\"]crust[\/pb_glossary], [pb_glossary id=\"1008\"]mafic[\/pb_glossary] [pb_glossary id=\"1658\"]crust[\/pb_glossary], [pb_glossary id=\"1009\"]ultramafic[\/pb_glossary] [pb_glossary id=\"1664\"]mantle[\/pb_glossary], and iron and nickel [pb_glossary id=\"1667\"]core[\/pb_glossary].<\/span>\n<h3><b>8.3.2 Origin of the Moon<\/b><\/h3>\n[caption id=\"attachment_3292\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Back_side_of_the_Moon_AS16-3021.jpg\"><img class=\"wp-image-540 size-medium\" title=\"By Apollo 16 astronauts [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABack_side_of_the_Moon_AS16-3021.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Back_side_of_the_Moon_AS16-3021-300x298.jpg\" alt=\"It looks different then the side we don't normally see.\" width=\"300\" height=\"298\"><\/a> Dark side of the Moon[\/caption]<span style=\"font-weight: 400\">Several unique features of Earth\u2019s Moon have prompted scientists to develop the current [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] about its [pb_glossary id=\"2038\"]formation[\/pb_glossary]. The Earth and Moon are tidally locked, meaning that as the Moon orbits, one side always faces the Earth and the opposite side is not visible to us. Also and most importantly, the chemical compositions of the Earth and Moon show nearly identical [pb_glossary id=\"1779\"]isotope[\/pb_glossary] ratios<\/span><span style=\"font-weight: 400\"> and volatile content<\/span><span style=\"font-weight: 400\">. <\/span>Apollo missions returned from the Moon with rocks that allowed scientists to conduct very precise comparisons between Moon and Earth rocks. Other bodies in the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] and [pb_glossary id=\"1254\"]meteorites[\/pb_glossary] do not share the same degree of similarity and show much higher variability. If the Moon and Earth formed together, this would explain why they are so chemically similar.\n\n[caption id=\"attachment_3293\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/ArtistsConceptMoonFormation.jpg\"><img class=\"wp-image-541 size-medium\" title=\"By NASA\/JPL-Caltech [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File:Artist%27s_concept_of_collision_at_HD_172555.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ArtistsConceptMoonFormation-300x240.jpg\" alt=\"The Earth and this object are colliding in a giant explosion.\" width=\"300\" height=\"240\"><\/a> Artist's concept of the giant impact from a Mars-sized object that could have formed the moon.[\/caption]Many ideas have been proposed for the origin of the Moon: The Moon could have been captured from another part of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] and formed in place together with the Earth, or the Moon could have been ripped out of the early Earth. None of proposed explanations can account for all the evidence. The currently prevailing [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] is the <strong>giant-impact [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary]<\/strong><span style=\"font-weight: 400\">. <\/span>It proposes a body about half of Earth\u2019s size must have shared at least parts of Earth\u2019s orbit and collided with it, resulting in a violent mixing and scattering of material from both objects. Both bodies would be [pb_glossary id=\"1909\"]composed[\/pb_glossary] of a combination of materials, with more of the lower density splatter coalescing into the Moon. This may explain why the Earth has a higher density and thicker [pb_glossary id=\"1667\"]core[\/pb_glossary] than the Moon.\n\n[caption id=\"attachment_4254\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-542\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/UIKmSQqp8wY[\/embed]\n\n<em><span style=\"font-weight: 400\">Computer simulation of the evolution of the Moon (2 minutes).<\/span><\/em>\n<h3><b>8.3.3 Origin of Earth\u2019s Water<\/b><\/h3>\n[caption id=\"attachment_3294\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Comet_on_7_July_2015_NavCam.jpg\"><img class=\"wp-image-543 size-medium\" title=\"&quot;ESA\/Rosetta\/NAVCAM,\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-300x300.jpg\" alt=\"Jets are seen coming off of the comet.\" width=\"300\" height=\"300\"><\/a> Water vapor leaves comet 67P\/Churyumov\u2013Gerasimenko.[\/caption]\n\n<span style=\"font-weight: 400\">Explanations for the origin of Earth\u2019s water include [pb_glossary id=\"228\"]volcanic[\/pb_glossary] outgassing, comets, and [pb_glossary id=\"1254\"]meteorites[\/pb_glossary]. The [pb_glossary id=\"228\"]volcanic[\/pb_glossary] outgassing [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] for the origin of Earth\u2019s water is that it originated from inside the planet, and emerged via [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes as vapor associated with [pb_glossary id=\"228\"]volcanic[\/pb_glossary] eruptions<\/span><span style=\"font-weight: 400\">.\u00a0 Since all [pb_glossary id=\"228\"]volcanic[\/pb_glossary] eruptions contain some water vapor, at times more than 1% of the volume, these alone could have created Earth\u2019s surface water. Another likely source of water was from space. Comets are a mixture of dust and ice, with some or most of that ice being frozen water. Seemingly dry meteors can contain small but measurable amounts of water, usually trapped in their [pb_glossary id=\"1765\"]mineral[\/pb_glossary] structures<\/span><span style=\"font-weight: 400\">. During heavy bombardment [pb_glossary id=\"1244\"]periods[\/pb_glossary] later in Earth\u2019s history, its cooled surface was pummeled by comets and [pb_glossary id=\"1254\"]meteorites[\/pb_glossary], which could be why so much water exists above ground. There isn\u2019t a definitive answer for what process is the source of ocean water. Earth\u2019s water isotopically matches water found in [pb_glossary id=\"1254\"]meteorites[\/pb_glossary] much better than that of comets<\/span><span style=\"font-weight: 400\">. However, it is hard to know if Earth processes could have changed the water\u2019s isotopic signature over the last 4-plus billion years<\/span><span style=\"font-weight: 400\">. <\/span>It is possible that all three sources contributed to the origin of Earth\u2019s water.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"50\"]\n\n[caption id=\"attachment_4242\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-544\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.3 via this QR Code.[\/caption]\n<h2><strong>8.4 Archean Eon<\/strong><\/h2>\n[caption id=\"attachment_3295\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Archean.png\"><img class=\"wp-image-545 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-300x134.png\" alt=\"It shows volcanoes, impacts, and stromatolites.\" width=\"300\" height=\"134\"><\/a> Artist's impression of the Archean.[\/caption]\n\n<span style=\"font-weight: 400\">The <strong>[pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]<\/strong>, which lasted from 4.0\u20132.5 billion years ago, is named after the Greek word for beginning. This [pb_glossary id=\"1242\"]eon[\/pb_glossary] represents the beginning of the rock record. Although there is current evidence that rocks and [pb_glossary id=\"1765\"]minerals[\/pb_glossary] existed during the [pb_glossary id=\"1255\"]Hadean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]<\/span><span style=\"font-weight: 400\">, <\/span>the [pb_glossary id=\"1257\"]Archean[\/pb_glossary] has a much more robust rock and [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record.\n\n&nbsp;\n\n&nbsp;\n<h3><b><\/b><span style=\"font-weight: 400\">8.4.1 Late Heavy Bombardment<\/span><\/h3>\n[caption id=\"attachment_3296\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pluto-in-true-color_2x_JPEG-edit-frame.jpg\"><img class=\"wp-image-546 size-medium\" title=\"NASA, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-300x300.jpg\" alt=\"The smooth plain is different than the cratered surrounding surface.\" width=\"300\" height=\"300\"><\/a> 2015 image from NASA's New Horizons probe of Pluto. The lack of impacts found on the Tombaugh Regio (the heart-shaped plain, lower right) has been inferred as being younger than the Late Heavy Bombardment and the surrounding surface due to its lack of impacts.[\/caption]\n\nObjects were chaotically flying around at the start of the [pb_glossary id=\"1253\"]solar system[\/pb_glossary], building the planets and moons. There is evidence that after the planets formed, about 4.1\u20133.8 billion years ago, a second large spike of asteroid and comet impacted the Earth and Moon in an event called <strong>[pb_glossary id=\"1258\"]late heavy bombardment[\/pb_glossary]<\/strong><span style=\"font-weight: 400\">. <\/span>[pb_glossary id=\"1254\"]Meteorites[\/pb_glossary] and comets in stable or semi-stable orbits became unstable and started impacting objects throughout the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]. In addition, this event is called the lunar cataclysm because most of the Moons craters are from this event. During [pb_glossary id=\"1258\"]late heavy bombardment[\/pb_glossary], the Earth, Moon, and all planets in the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] were pummeled by material from the asteroid and Kuiper belts. Evidence of this bombardment was found within samples collected from the Moon.\n\n[caption id=\"attachment_3297\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Lhborbits.png\"><img class=\"wp-image-547 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-300x100.png\" alt=\"It shows 3 pictures.\" width=\"300\" height=\"100\"><\/a> Simulation of before, during, and after the late heavy bombardment.[\/caption]\n\n<span style=\"font-weight: 400\">It is universally accepted that the [pb_glossary id=\"1253\"]solar system[\/pb_glossary] experienced extensive asteroid and comet bombardment at its start; however, some other process must have caused the second increase in impacts hundreds of millions of years later. A leading [pb_glossary id=\"1733\"]theory[\/pb_glossary] blames gravitational [pb_glossary id=\"2181\"]resonance[\/pb_glossary] between Jupiter and Saturn for disturbing orbits within the asteroid and Kuiper belts <\/span>based on a similar process observed in the Eta Corvi star [pb_glossary id=\"1742\"]system[\/pb_glossary]<span style=\"font-weight: 400\">.<\/span>\n<h3><b>8.4.2 Origin of the Continents<\/b><\/h3>\n[caption id=\"attachment_2512\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earth-cutaway-schematic-english.svg_-1.png\"><img class=\"size-medium wp-image-51\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-300x211.png\" alt=\"The crust and lithosphere are on the outside of the Earth and are thin. Below the crust is the mantle and core. Below the lithosphere is the asthenosphere.\" width=\"300\" height=\"211\"><\/a> The layers of the Earth. Physical layers include lithosphere and asthenosphere; chemical layers are crust, mantle, and core.[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">In order for [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary] to work as it does currently, it necessarily must have continents. However, the easiest way to create [pb_glossary id=\"1653\"]continental[\/pb_glossary] material is via [pb_glossary id=\"225\"]assimilation[\/pb_glossary] and differentiation of existing continents (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>). This chicken-and-egg quandary over how continents were made in the first place is not easily answered because of the great age of [pb_glossary id=\"1653\"]continental[\/pb_glossary] material and how much evidence has been lost during [pb_glossary id=\"1654\"]tectonics[\/pb_glossary] and [pb_glossary id=\"1755\"]erosion[\/pb_glossary]. While the timing and specific processes are still debated, [pb_glossary id=\"228\"]volcanic[\/pb_glossary] action must have brought the first [pb_glossary id=\"1653\"]continental[\/pb_glossary] material to the Earth\u2019s surface during the [pb_glossary id=\"1255\"]Hadean[\/pb_glossary], 4.4 billion years ago<\/span><span style=\"font-weight: 400\">. <\/span>This model does not solve the problem of [pb_glossary id=\"1653\"]continent[\/pb_glossary] [pb_glossary id=\"2038\"]formation[\/pb_glossary], since [pb_glossary id=\"226\"]magmatic differentiation[\/pb_glossary] seems to need thicker [pb_glossary id=\"1658\"]crust[\/pb_glossary]. Nevertheless, the continents formed by some incremental process during the early history of Earth<span style=\"font-weight: 400\">. The best idea is that density differences allowed lighter [pb_glossary id=\"1006\"]felsic[\/pb_glossary] materials to float upward and heavier [pb_glossary id=\"1009\"]ultramafic[\/pb_glossary] materials and [pb_glossary id=\"2423\"]metallic[\/pb_glossary] iron to sink. These density differences led to the layering of the Earth, the layers that are now detected by [pb_glossary id=\"2165\"]seismic[\/pb_glossary] studies. Early protocontinents accumulated [pb_glossary id=\"1006\"]felsic[\/pb_glossary] materials as developing [pb_glossary id=\"1669\"]plate[\/pb_glossary]-[pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes brought lighter material from the [pb_glossary id=\"1664\"]mantle[\/pb_glossary] to the surface<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3299\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fig21oceanocean.gif\"><img class=\"wp-image-3299 size-medium\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig21oceanocean-1.gif\" alt=\"The ocean plate subducts beneath a different ocean plate.\" width=\"300\" height=\"173\"><\/a> Subduction of an oceanic plate beneath another oceanic plate, forming a trench and an island arc. Several island arcs might combine and eventually evolve into a continent.[\/caption]\n\n<span style=\"font-weight: 400\">The first solid evidence of modern [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary] is found at the end of the [pb_glossary id=\"1257\"]Archean[\/pb_glossary], indicating at least some [pb_glossary id=\"1653\"]continental[\/pb_glossary] [pb_glossary id=\"1668\"]lithosphere[\/pb_glossary] must have been in place. This evidence does not necessarily mark the starting point of [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary]; remnants of earlier [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] activity could have been erased by the [pb_glossary id=\"1749\"]rock cycle[\/pb_glossary]<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_2523\" align=\"alignright\" width=\"419\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/CratonGeolProv.jpg\"><img class=\"wp-image-92\" title=\"By USGS (http:\/\/earthquake.usgs.gov\/data\/crust\/maps.php) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AWorld_geologic_provinces.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CratonGeolProv-300x159.jpg\" alt=\"The legend shows shields, platforms, orogens, basins, large igneous provinces, and extended crust.\" width=\"419\" height=\"222\"><\/a> Geologic provinces of Earth. Cratons are pink and orange.[\/caption]The stable interiors of the current continents are called <strong>[pb_glossary id=\"1718\"]cratons[\/pb_glossary]<\/strong> and were mostly formed in the [pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]. A [pb_glossary id=\"1718\"]craton[\/pb_glossary] has two main parts: the <strong>[pb_glossary id=\"1259\"]shield[\/pb_glossary]<\/strong>, which is crystalline [pb_glossary id=\"1023\"]basement[\/pb_glossary] rock near the surface, and the <strong>[pb_glossary id=\"1260\"]platform[\/pb_glossary]<\/strong> made of sedimentary rocks covering the [pb_glossary id=\"1259\"]shield[\/pb_glossary]. Most [pb_glossary id=\"1718\"]cratons[\/pb_glossary] have remained relatively unchanged with most [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] activity having occurred around [pb_glossary id=\"1718\"]cratons[\/pb_glossary] instead of within them. Whether they were created by [pb_glossary id=\"1654\"]plate tectonics[\/pb_glossary] or another process, [pb_glossary id=\"1257\"]Archean[\/pb_glossary] continents gave rise to the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] continents that now dominate our planet.\n\n[caption id=\"attachment_3300\" align=\"alignleft\" width=\"258\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Zealandia_topography.jpg\"><img class=\"wp-image-549 size-medium\" title=\"By World Data Center for Geophysics &amp;amp; Marine Geology (Boulder, CO), National Geophysical Data Center, NOAA [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AZealandia_topography.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Zealandia_topography-258x300.jpg\" alt=\"It shows Zealandia\" width=\"258\" height=\"300\"><\/a> The continent of Zealandia[\/caption]<span style=\"font-weight: 400\">The general guideline as to what constitutes a [pb_glossary id=\"1653\"]continent[\/pb_glossary] and differentiates [pb_glossary id=\"1659\"]oceanic[\/pb_glossary] from [pb_glossary id=\"1653\"]continental crust[\/pb_glossary] is under some debate. At passive margins, [pb_glossary id=\"1653\"]continental crust[\/pb_glossary] grades into [pb_glossary id=\"1659\"]oceanic crust[\/pb_glossary] at passive margins, making a distinction difficult<\/span><span style=\"font-weight: 400\">. Even island-[pb_glossary id=\"1687\"]arc[\/pb_glossary] and hot-spot material can seem more closely related to [pb_glossary id=\"1653\"]continental crust[\/pb_glossary] than [pb_glossary id=\"1659\"]oceanic[\/pb_glossary]. Continents usually have a [pb_glossary id=\"1718\"]craton[\/pb_glossary] in the middle with [pb_glossary id=\"1006\"]felsic[\/pb_glossary] [pb_glossary id=\"1753\"]igneous[\/pb_glossary] rocks. There is evidence that submerged masses like Zealandia, that includes present-day New Zealand, would be considered a [pb_glossary id=\"1653\"]continent[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. [pb_glossary id=\"1653\"]Continental crust[\/pb_glossary] that does not contain a [pb_glossary id=\"1718\"]craton[\/pb_glossary] is called a [pb_glossary id=\"1653\"]continental[\/pb_glossary] fragment, such as the island of Madagascar off the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] of Africa<\/span><span style=\"font-weight: 400\">.<\/span>\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n<h3><b>8.4.3 First Life on Earth<\/b><\/h3>\n[caption id=\"attachment_3301\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicrobialMats.jpg\"><img class=\"wp-image-550 size-medium\" title=\"By Smith609 (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ARunzelmarken.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MicrobialMats-300x167.jpg\" alt=\"Rocks with a wrinkled texture, formed by microbial mats\" width=\"300\" height=\"167\"><\/a> Fossils of microbial mats from Sweden[\/caption]Life most likely started during the late [pb_glossary id=\"1255\"]Hadean[\/pb_glossary] or early [pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eons[\/pb_glossary]. The earliest evidence of life are chemical signatures, microscopic filaments, and microbial mats. Carbon found in 4.1 billion year old [pb_glossary id=\"1227\"]zircon[\/pb_glossary] grains have a chemical signature suggesting an organic origin. Other evidence of early life are 3.8\u20134.3 billion-year-old microscopic filaments from a [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] [pb_glossary id=\"234\"]vent[\/pb_glossary] deposit in Quebec, Canada. While the chemical and microscopic filaments evidence is not as robust as [pb_glossary id=\"1228\"]fossils[\/pb_glossary], there is significant [pb_glossary id=\"1228\"]fossil[\/pb_glossary] evidence for life at 3.5 billion years ago. These first well-preserved [pb_glossary id=\"1228\"]fossils[\/pb_glossary] are photosynthetic microbial mats, called [pb_glossary id=\"1265\"]stromatolites[\/pb_glossary], found in Australia.\n\n[caption id=\"attachment_3302\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/15.2_greenhouse-gas-molecules.jpg\"><img class=\"wp-image-551 size-medium\" title=\"https:\/\/climate.nasa.gov\/system\/internal_resources\/details\/original\/249_Causes-greenhouse-gas-molecules-cropped-more-55.jpg\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-300x192.jpg\" alt=\"Illustration of the molecular shape of greenhouse gases.\" width=\"300\" height=\"192\"><\/a> Greenhouse gases were more common in Earth\u2019s early atmosphere.[\/caption]\n\nAlthough the origin of life on Earth is unknown, [pb_glossary id=\"1730\"]hypotheses[\/pb_glossary] include a chemical origin in the early [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] and ocean, deep-sea [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] vents, and delivery to Earth by comets or other objects. One [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] is that life arose from the chemical environment of the Earth\u2019s early [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] and oceans, which was very different than today. The oxygen-free [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] produced a reducing environment with abundant methane, carbon dioxide, sulfur, and nitrogen compounds. This is what the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] is like on other bodies in the [pb_glossary id=\"1253\"]solar system[\/pb_glossary]. In the famous Miller-Urey [pb_glossary id=\"1731\"]experiment[\/pb_glossary], researchers simulated early Earth\u2019s [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] and lightning within a sealed vessel. After igniting sparks within the vessel, they discovered the [pb_glossary id=\"2038\"]formation[\/pb_glossary] of amino acids, the fundamental building blocks of proteins.\u00a0 In 1977, when scientists discovered an isolated ecosystem around [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] vents on a deep-sea [pb_glossary id=\"1708\"]mid-ocean ridge[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>), it opened the door for another explanation of the origin of life. The [pb_glossary id=\"1999\"]hydrothermal[\/pb_glossary] vents have a unique ecosystem of critters with [pb_glossary id=\"231\"]chemosynthesis[\/pb_glossary] as the foundation of the food chain instead of photosynthesis. The ecosystem is deriving its energy from hot chemical-rich waters pouring out of underground towers. This suggests that life could have started on the deep [pb_glossary id=\"1963\"]ocean floor[\/pb_glossary] and derived energy from the heat from the Earth\u2019s interior via [pb_glossary id=\"231\"]chemosynthesis[\/pb_glossary]. Scientists have since expanded the search for life to more unconventional places, like Jupiter\u2019s icy moon Europa.\n\n[caption id=\"attachment_4244\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.4.3-Animation-QR-Code.png\"><img class=\"size-thumbnail wp-image-552\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this animation via this QR Code.[\/caption]\n\n[video width=\"854\" height=\"480\" webm=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2017\/03\/Miller-Urey_experiment_-_Work_by_the_C3BC_consortium_licensed_under_CC-BY-3.0.webm.480p.webm\"][\/video]\n\n<em>Animation of the original Miller-Urey 1959 [pb_glossary id=\"1731\"]<em>experiment<\/em>[\/pb_glossary] that simulated the early [pb_glossary id=\"1745\"]<em>atmosphere<\/em>[\/pb_glossary] and created amino acids from simple [pb_glossary id=\"1778\"]<em>elements<\/em>[\/pb_glossary] and compounds. <\/em>\n\nAnother possibility is that life or its building blocks came to Earth from space, carried aboard comets or other objects. Amino acids, for example, have been found within comets and [pb_glossary id=\"1254\"]meteorites[\/pb_glossary]. This intriguing possibility also implies a high likelihood of life existing elsewhere in the cosmos.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"51\"]\n\n[caption id=\"attachment_4243\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-553\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.4 via this QR Code.[\/caption]\n<h2><strong><span style=\"font-size: 28px\">8.5 Proterozoic Eon<\/span><\/strong><\/h2>\n[caption id=\"attachment_3303\" align=\"alignleft\" width=\"216\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Photosynthesis.gif\"><img class=\"wp-image-554 size-medium\" title=\"By At09kg (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3APhotosynthesis.gif&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Photosynthesis-216x300.gif\" alt=\"Water and carbon dioxide go into plants, making sugar and oxygen.\" width=\"216\" height=\"300\"><\/a> Diagram showing the main products and reactants in photosynthesis. The one product that is not shown is sugar, which is the chemical energy that goes into constructing the plant, and the energy that is stored in the plant which is used later by the plant or by animals that consume the plant.[\/caption]The <strong>[pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]<\/strong>, meaning \u201cearlier life,\u201d comes after the [pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary] and ranges from 2.5 billion to 541 million years old. During this time, most of the central parts of the continents had formed and [pb_glossary id=\"1669\"]plate[\/pb_glossary] [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] processes had started. Photosynthesis by microbial organisms, such as single-celled cyanobacteria, had been slowly adding oxygen to the oceans. As cyanobacteria evolved into multicellular organisms, they completely transformed the oceans and later the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] by adding [pb_glossary id=\"985\"]massive[\/pb_glossary] amounts of free oxygen gas (O<sub>2<\/sub>) and initiated what is called the <strong>[pb_glossary id=\"1262\"]Great Oxygenation Event[\/pb_glossary] (GOE<\/strong>). This drastic environmental change decimated the anaerobic bacteria, which could not survive in the presence of free oxygen. On the other hand, aerobic organisms could thrive in ways they could not earlier<span style=\"font-weight: 400\">. <\/span>\n\nAn oxygenated world also changed the chemistry of the planet in significant ways. For example, iron remained in [pb_glossary id=\"1783\"]solution[\/pb_glossary] in the non-oxygenated environment of the earlier [pb_glossary id=\"1257\"]Archean[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary]. In chemistry, this is known as a reducing environment. Once the environment was oxygenated, iron combined with free oxygen to form solid precipitates of iron [pb_glossary id=\"971\"]oxide[\/pb_glossary], such as the [pb_glossary id=\"1765\"]mineral[\/pb_glossary] hematite or magnetite. These precipitates accumulated into large [pb_glossary id=\"1765\"]mineral[\/pb_glossary] deposits with red [pb_glossary id=\"1927\"]chert[\/pb_glossary] known as [pb_glossary id=\"2009\"]banded[\/pb_glossary]-iron [pb_glossary id=\"2038\"]formations[\/pb_glossary], which are dated at about 2 billion years<span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3304\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MichiganBIF-1.jpg\"><img class=\"wp-image-371 size-medium\" title=\"By Wilson44691 (Own work) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AMichiganBIF.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MichiganBIF-1-300x206.jpg\" alt=\"The rock shows red and brown layering.\" width=\"300\" height=\"206\"><\/a> Alternating bands of iron-rich and silica-rich mud, formed as oxygen combined with dissolved iron.[\/caption]&nbsp;\n\nThe [pb_glossary id=\"2038\"]formation[\/pb_glossary] of iron [pb_glossary id=\"971\"]oxide[\/pb_glossary] [pb_glossary id=\"1765\"]minerals[\/pb_glossary] and red [pb_glossary id=\"1927\"]chert[\/pb_glossary] (see figure) in the oceans lasted a long time and prevented oxygen levels from increasing significantly, since [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] took the oxygen out of the water and deposited it into the rock [pb_glossary id=\"1935\"]strata[\/pb_glossary]. As oxygen continued to be produced and [pb_glossary id=\"1765\"]mineral[\/pb_glossary] [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] leveled off, [pb_glossary id=\"1893\"]dissolved[\/pb_glossary] oxygen gas eventually [pb_glossary id=\"1784\"]saturated[\/pb_glossary] the oceans and started bubbling out into the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]. Oxygenation of the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] is the single biggest event that distinguishes the [pb_glossary id=\"1257\"]Archean[\/pb_glossary] and [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] environments. In addition to changing [pb_glossary id=\"1765\"]mineral[\/pb_glossary] and ocean chemistry, the GOE is also tabbed as triggering Earth\u2019s first [pb_glossary id=\"747\"]glaciation[\/pb_glossary] event around 2.1 billion years ago, the Huron [pb_glossary id=\"747\"]Glaciation[\/pb_glossary]. Free oxygen reacted with methane in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] to produce carbon dioxide. Carbon dioxide and methane are called greenhouse gases because they [pb_glossary id=\"2420\"]trap[\/pb_glossary] heat within the Earth\u2019s [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary], like the insulated glass of a greenhouse. Methane is a more effective insulator than carbon dioxide, so as the proportion of carbon dioxide in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] increased, the [pb_glossary id=\"762\"]greenhouse effect[\/pb_glossary] decreased, and the planet cooled.\n<h3><b>8.5.1 Rodinia<\/b><\/h3>\n[caption id=\"attachment_3305\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Rodinia_reconstruction.jpg\"><img class=\"wp-image-555 size-medium\" title=\"By John Goodge [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ARodinia_reconstruction.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rodinia_reconstruction-300x267.jpg\" alt=\"The image shows the continents arrange in a possible orientation of Rodinia.\" width=\"300\" height=\"267\"><\/a> One possible reconstruction of Rodinia 1.1 billion years ago. Source: John Goodge, modified from (Dalziel 1997).[\/caption]<span style=\"font-weight: 400\">By the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary], lithospheric plates had formed and were moving according to [pb_glossary id=\"1669\"]plate[\/pb_glossary] [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] forces that were similar to current times. As the moving [pb_glossary id=\"1669\"]plates[\/pb_glossary] collided, the ocean basins closed to form a <strong>[pb_glossary id=\"1701\"]supercontinent[\/pb_glossary]<\/strong> called <strong>[pb_glossary id=\"1263\"]Rodinia[\/pb_glossary]<\/strong>. The [pb_glossary id=\"1701\"]supercontinent[\/pb_glossary] formed about 1 billion years ago and broke up about 750 to 600 million years ago, at the end of the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. <\/span>One of the resulting fragments was a [pb_glossary id=\"1653\"]continental[\/pb_glossary] mass called <strong>[pb_glossary id=\"1264\"]Laurentia[\/pb_glossary]<\/strong> that would later become North America. Geologists have reconstructed [pb_glossary id=\"1263\"]Rodinia[\/pb_glossary] by matching and aligning ancient mountain chains, assembling the pieces like a jigsaw puzzle, and using paleomagnetics to orient to magnetic north.\n\n<span style=\"font-weight: 400\">The disagreements over these complex reconstructions is exemplified by geologists proposing at least six different models for the breakup of [pb_glossary id=\"1263\"]Rodinia[\/pb_glossary] to create Australia<\/span><span style=\"font-weight: 400\">, Antarctica<\/span><span style=\"font-weight: 400\">, parts of China<\/span><span style=\"font-weight: 400\">, the Tarim [pb_glossary id=\"1718\"]craton[\/pb_glossary] north of the Himalaya<\/span><span style=\"font-weight: 400\">, Siberia<\/span><span style=\"font-weight: 400\">, or the Kalahari [pb_glossary id=\"1718\"]craton[\/pb_glossary] of eastern Africa<\/span><span style=\"font-weight: 400\">. <\/span>This breakup created lots of shallow-water, biologically favorable environments that fostered the evolutionary breakthroughs marking the start of the next [pb_glossary id=\"1242\"]eon[\/pb_glossary], the [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary].\n\n&nbsp;\n<h3><b>8.5.2 Life Evolves<\/b><\/h3>\n[caption id=\"attachment_3306\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Stromatolites_in_Sharkbay.jpg\"><img class=\"wp-image-556 size-medium\" title=\"By Paul Harrison [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStromatolites_in_Sharkbay.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Stromatolites_in_Sharkbay-300x223.jpg\" alt=\"Picture of modern cyanobacteria (as stromatolites) in Shark Bay, Australia. The brown, blobby stromatolites are slightly sticking out of the shallow water of the ocean.\" width=\"300\" height=\"223\"><\/a> Modern cyanobacteria (as stromatolites) in Shark Bay, Australia.[\/caption]Early life in the [pb_glossary id=\"1257\"]Archean[\/pb_glossary] and earlier is poorly documented in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record. Based on chemical evidence and evolutionary [pb_glossary id=\"1733\"]theory[\/pb_glossary], scientists propose this life would have been single-celled photosynthetic organisms, such as the cyanobacteria that created <strong>[pb_glossary id=\"1265\"]stromatolites[\/pb_glossary]<\/strong>. Cyanobacteria produced free oxygen in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] through photosynthesis. Cyanobacteria, archaea, and bacteria are <strong>[pb_glossary id=\"1266\"]prokaryotes[\/pb_glossary]<\/strong>\u2014primitive organisms made of single cells that lack cell nuclei and other organelles.\n\n[caption id=\"attachment_3307\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Stromatolites_hoyt.jpg\"><img class=\"wp-image-557 size-medium\" title=\"By Rygel, M.C. (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStromatolites_hoyt_mcr1.JPG&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Stromatolites_hoyt-300x200.jpg\" alt=\"Round structures of grey limestone are remnants of the blobby nature of the living stromatolites, fossilized in rock.\" width=\"300\" height=\"200\"><\/a> Fossil stromatolites in Saratoga Springs, New York.[\/caption]A large evolutionary step occurred during the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary] with the appearance of <strong>[pb_glossary id=\"1267\"]eukaryotes[\/pb_glossary]<\/strong> around 2.1 to 1.6 billion years ago. [pb_glossary id=\"1267\"]Eukaryotic[\/pb_glossary] cells are more complex, having nuclei and organelles. The nuclear DNA is capable of more complex replication and regulation than that of [pb_glossary id=\"1266\"]prokaryotic[\/pb_glossary] cells. The organelles include mitochondria for producing energy and chloroplasts for photosynthesis. The [pb_glossary id=\"1267\"]eukaryote[\/pb_glossary] branch in the tree of life gave rise to fungi, plants, and animals.\n\nAnother important event in Earth\u2019s biological history occurred about 1.2 billion years ago when [pb_glossary id=\"1267\"]eukaryotes[\/pb_glossary] invented sexual reproduction. Sharing genetic material from two reproducing individuals, male and female, greatly increased genetic variability in their offspring. This genetic mixing accelerated evolutionary change, contributing to more complexity among individual organisms and within ecosystems (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">Chapter 7<\/a>).\n\n[pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] land surfaces were barren of plants and animals and geologic processes actively shaped the environment differently because land surfaces were not protected by leafy and woody vegetation. For example, rain and [pb_glossary id=\"2212\"]rivers[\/pb_glossary] would have caused [pb_glossary id=\"1755\"]erosion[\/pb_glossary] at much higher rates on land surfaces devoid of plants. This resulted in thick accumulations of pure [pb_glossary id=\"967\"]quartz[\/pb_glossary] [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] from the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eon[\/pb_glossary] such as the extensive [pb_glossary id=\"2013\"]quartzite[\/pb_glossary] [pb_glossary id=\"2038\"]formations[\/pb_glossary] in the [pb_glossary id=\"1667\"]core[\/pb_glossary] of the Uinta Mountains in Utah.\n\n[caption id=\"attachment_3308\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/DickinsoniaCostata.jpg\"><img class=\"wp-image-558 size-medium\" title=\"<a href=&quot;https:\/\/en.wikipedia.org\/wiki\/User:Verisimilus&quot; class=&quot;extiw&quot; title=&quot;wikipedia:User:Verisimilus&quot;>Verisimilus<\/a> at <a href=&quot;https:\/\/en.wikipedia.org\/wiki\/&quot; class=&quot;extiw&quot; title=&quot;wikipedia:&quot;>English Wikipedia<\/a> [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>, <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by\/2.5&quot;>CC BY 2.5<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADickinsoniaCostata.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/DickinsoniaCostata-300x225.jpg\" alt=\"The fossil is a flat, leaf-shaped\" width=\"300\" height=\"225\"><\/a> Dickinsonia, a typical Ediacaran fossil.[\/caption]Fauna during the [pb_glossary id=\"1268\"]Ediacaran[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary], 635.5 to 541 million years ago are known as the <strong>[pb_glossary id=\"1268\"]Ediacaran fauna[\/pb_glossary]<\/strong>, and offer a first glimpse at the diversity of ecosystems that evolved near the end of the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary]. These soft-bodied organisms were among the first multicellular life forms and probably were similar to jellyfish or worm-like. [pb_glossary id=\"1268\"]Ediacaran fauna[\/pb_glossary] did not have hard parts like shells and were not well preserved in the rock records. However, studies suggest they were widespread in the Earth\u2019s oceans. Scientists still debate how many species were evolutionary dead-ends that became [pb_glossary id=\"755\"]extinct[\/pb_glossary] and how many were ancestors of modern groupings. The transition of soft-bodied [pb_glossary id=\"1268\"]Ediacaran[\/pb_glossary] life to life forms with hard body parts occurred at the end of the [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] and beginning of the [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary] [pb_glossary id=\"1242\"]Eons[\/pb_glossary]. This evolutionary explosion of biological diversity made a dramatic difference in scientists\u2019 ability to understand the history of life on Earth.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"52\"]\n\n[caption id=\"attachment_4245\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.5-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-559\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.5 via this QR Code.[\/caption]\n<h2><strong>8.6 Phanerozoic Eon: Paleozoic Era<\/strong><\/h2>\n[caption id=\"attachment_3249\" align=\"alignleft\" width=\"243\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/ElrathiakingiUtahWheelerCambrian.jpg\"><img class=\"wp-image-497 size-medium\" title=\"By Wilson44691 (Own work) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AElrathiakingiUtahWheelerCambrian.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ElrathiakingiUtahWheelerCambrian-243x300.jpg\" alt=\"It has three lobes\" width=\"243\" height=\"300\"><\/a> The trilobites had a hard exoskeleton, and is an early arthropod, the same group that includes modern insects, crustaceans, and arachnids.[\/caption]<span style=\"font-weight: 400\">The <strong>[pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary]<\/strong> [pb_glossary id=\"1242\"]Eon[\/pb_glossary] is the most recent, 541 million years ago to today, <\/span>and means \u201cvisible life\u201d because the [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary] rock record is marked by an abundance of [pb_glossary id=\"1228\"]fossils[\/pb_glossary]. [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary] organisms had hard body parts like claws, scales, shells, and bones that were more easily preserved as [pb_glossary id=\"1228\"]fossils[\/pb_glossary]. Rocks from the older [pb_glossary id=\"1270\"]Precambrian[\/pb_glossary] time are less commonly found and rarely include [pb_glossary id=\"1228\"]fossils[\/pb_glossary] because these organisms had soft body parts. [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary] rocks are younger, more common, and contain the majority of extant [pb_glossary id=\"1228\"]fossils[\/pb_glossary]. The study of rocks from this [pb_glossary id=\"1242\"]eon[\/pb_glossary] yields much greater detail. The [pb_glossary id=\"1269\"]Phanerozoic[\/pb_glossary] is subdivided into three [pb_glossary id=\"1243\"]eras[\/pb_glossary], from oldest to youngest they are [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] (\u201cancient life\u201d), [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] (\u201cmiddle life\u201d), and [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] (\u201crecent life\u201d) and the remaining three chapter headings are on these three important [pb_glossary id=\"1243\"]eras[\/pb_glossary].\n\n[caption id=\"attachment_3309\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Trilobite_Heinrich_Harder.jpg\"><img class=\"wp-image-560 size-medium\" title=\"Trilobites, by Heinrich Harder, 1916.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-300x186.jpg\" alt=\"The trilobites are crawling over the sea floor\" width=\"300\" height=\"186\"><\/a> Trilobites, by Heinrich Harder, 1916.[\/caption]\n\n<span style=\"font-weight: 400\">Life in the early <strong>[pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary]<\/strong> was dominated by [pb_glossary id=\"1961\"]marine[\/pb_glossary] organisms but by the middle of the [pb_glossary id=\"1243\"]era[\/pb_glossary] plants and animals evolved to live and reproduce on land. Fish evolved jaws and fins evolved into jointed limbs. The development of lungs allowed animals to emerge from the sea and become the first air-breathing tetrapods (four-legged animals) such as amphibians. From amphibians evolved reptiles with the amniotic egg. From reptiles evolved an early ancestor to birds and mammals <\/span><span style=\"font-weight: 400\">and their scales became feathers and fur. Near the end of the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary], the [pb_glossary id=\"475\"]Carboniferous[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary] had some of the most extensive forests in Earth\u2019s history. Their fossilized remains became the [pb_glossary id=\"1934\"]coal[\/pb_glossary] that powered the industrial revolution<\/span>\n<h3><strong>8.6.1 Paleozoic Tectonics and Paleogeography<\/strong><\/h3>\n[caption id=\"attachment_3310\" align=\"alignleft\" width=\"256\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/North_america_craton_nps.gif\"><img class=\"wp-image-561 size-medium\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-256x300.gif\" alt=\"It is a map of North America\" width=\"256\" height=\"300\"><\/a> Laurentia, which makes up the North American craton.[\/caption]\n\nDuring the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary], sea-levels rose and fell four times. With each sea-level rise, the majority of North America was covered by a shallow tropical ocean. Evidence of these submersions are the abundant [pb_glossary id=\"1961\"]marine[\/pb_glossary] sedimentary rocks such as [pb_glossary id=\"1929\"]limestone[\/pb_glossary] with [pb_glossary id=\"1228\"]fossils[\/pb_glossary] corals and [pb_glossary id=\"1923\"]ooids[\/pb_glossary]. Extensive sea-level [pb_glossary id=\"2197\"]falls[\/pb_glossary] are documented by widespread [pb_glossary id=\"2039\"]unconformities[\/pb_glossary]. Today, the midcontinent has extensive [pb_glossary id=\"1961\"]marine[\/pb_glossary] sedimentary rocks from the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] and western North America has thick layers of [pb_glossary id=\"1961\"]marine[\/pb_glossary] [pb_glossary id=\"1929\"]limestone[\/pb_glossary] on block faulted mountain ranges such as Mt. Timpanogos near Provo, Utah<span style=\"font-weight: 400\">.\u00a0<\/span>\n\n[caption id=\"attachment_3311\" align=\"alignright\" width=\"267\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pangaea_continents.png\"><img class=\"wp-image-3311 size-medium\" title=\"By en:User:Kieff (File:Pangaea continents.png) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3APangaea_continents.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangaea_continents-1.png\" alt=\"Pangaea has a crescent shape.\" width=\"267\" height=\"300\"><\/a> A reconstruction of Pangaea, showing approximate positions of modern continents.[\/caption]<span style=\"font-weight: 400\">The assembly of [pb_glossary id=\"1701\"]supercontinent[\/pb_glossary] <strong>[pb_glossary id=\"2444\"]Pangea[\/pb_glossary]<\/strong>, sometimes spelled [pb_glossary id=\"2444\"]Pangaea[\/pb_glossary], was completed by the late [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary]. The name [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] was originally coined by Alfred Wegener and means \u201call land.\u201d [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] is the when all of the major continents were grouped together as one by a series of [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] events including [pb_glossary id=\"1680\"]subduction[\/pb_glossary] island-[pb_glossary id=\"1687\"]arc[\/pb_glossary] accretion, and [pb_glossary id=\"1653\"]continental[\/pb_glossary] collisions, and ocean-[pb_glossary id=\"508\"]basin[\/pb_glossary] closures. In North America, these [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] events occurred on the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] and are known as the Taconic, Acadian, Caledonian, and Alleghanian orogenies<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\"> The Appalachian Mountains are the erosional remnants of these mountain building events in North America. Surrounding [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] was a global ocean [pb_glossary id=\"508\"]basin[\/pb_glossary] known as the Panthalassa. Continued [pb_glossary id=\"1669\"]plate[\/pb_glossary] movement extended the ocean into [pb_glossary id=\"2444\"]Pangea[\/pb_glossary], forming a large bay called the Tethys Sea that eventually divided the land mass into two smaller [pb_glossary id=\"1701\"]supercontinents[\/pb_glossary], Laurasia and Gondwana. Laurasia consisted of [pb_glossary id=\"1264\"]Laurentia[\/pb_glossary] and Eurasia, and Gondwana consisted of the remaining continents of South America, Africa, India, Australia, and Antarctica. <\/span>\n\n[caption id=\"attachment_4254\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-542\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/ovT90wYrVk4[\/embed]\n\n<em>Animation of [pb_glossary id=\"1669\"]<em>plate<\/em>[\/pb_glossary] movement the last 3.3 billion years. [pb_glossary id=\"2444\"]<em>Pangea<\/em>[\/pb_glossary] occurs at the 4:40 mark.<\/em>\n\nWhile the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] of North America was tectonically active during the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary], the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] remained mostly inactive as a [pb_glossary id=\"1676\"]passive margin[\/pb_glossary] during the early [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary]. The western edge of North American [pb_glossary id=\"1653\"]continent[\/pb_glossary] was near the present-day Nevada-Utah border and was an expansive shallow [pb_glossary id=\"1969\"]continental shelf[\/pb_glossary] near the paleoequator. However, by the [pb_glossary id=\"1279\"]Devonian[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary], the Antler [pb_glossary id=\"1663\"]orogeny[\/pb_glossary] started on the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] and lasted until the Pennsylvanian [pb_glossary id=\"1244\"]Period[\/pb_glossary]. The Antler [pb_glossary id=\"1663\"]orogeny[\/pb_glossary] was a [pb_glossary id=\"228\"]volcanic[\/pb_glossary] [pb_glossary id=\"1697\"]island arc[\/pb_glossary] that was accreted onto western North America with the [pb_glossary id=\"1680\"]subduction[\/pb_glossary] direction away from North America. This created a mountain range on the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] of North American called the Antler highlands and was the first part of building the land in the west that would eventually make most of California, Oregon, and Washington states. By the late [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary], the Sonoma [pb_glossary id=\"1663\"]orogeny[\/pb_glossary] began on the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] and was another [pb_glossary id=\"1698\"]collision[\/pb_glossary] of an [pb_glossary id=\"1697\"]island arc[\/pb_glossary]. The Sonoma [pb_glossary id=\"1663\"]orogeny[\/pb_glossary] marks the change in [pb_glossary id=\"1680\"]subduction[\/pb_glossary] direction to be toward North America with a [pb_glossary id=\"1695\"]volcanic arc[\/pb_glossary] along the entire west [pb_glossary id=\"1968\"]coast[\/pb_glossary] of North America by late [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] to early [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Eras[\/pb_glossary]<span style=\"font-weight: 400\">.<\/span>\n\nBy the end of the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary], the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] of North America had a very high mountain range due to [pb_glossary id=\"1653\"]continental[\/pb_glossary] [pb_glossary id=\"1698\"]collision[\/pb_glossary] and the creation of [pb_glossary id=\"2444\"]Pangea[\/pb_glossary]. The west [pb_glossary id=\"1968\"]coast[\/pb_glossary] of North America had smaller and isolated [pb_glossary id=\"228\"]volcanic[\/pb_glossary] highlands associated with [pb_glossary id=\"1697\"]island arc[\/pb_glossary] accretion. During the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary], the size of the mountains on either side of North America would flip, with the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] being a more tectonically active [pb_glossary id=\"1670\"]plate boundary[\/pb_glossary] and the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] changing into a [pb_glossary id=\"1676\"]passive margin[\/pb_glossary] after the breakup of [pb_glossary id=\"2444\"]Pangea[\/pb_glossary].\n<h3><strong>8.6.2 Paleozoic Evolution<\/strong><\/h3>\n[caption id=\"attachment_3312\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Anomalocaris.jpg\"><img class=\"wp-image-563 size-medium\" title=\"See page for author [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AAnomalocaris_canadensis_-_reconstruction_-_MUSE.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Anomalocaris-300x200.jpg\" alt=\"The animal has two arms and large eyes.\" width=\"300\" height=\"200\"><\/a> Anomalocaris reconstruction by the MUSE science museum in Italy.[\/caption]<span style=\"font-weight: 400\">The beginning of the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary] is marked by the first appearance of hard body parts like shells, spikes, teeth, and scales; and the appearance in the rock record of most animal phyla known today. That is, most basic animal body plans appeared in the rock record during the [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary]. This sudden appearance of biological diversity is called the <strong>[pb_glossary id=\"1272\"]Cambrian Explosion[\/pb_glossary]. <\/strong>Scientists debate whether this sudden appearance is more from a rapid evolutionary diversification as a result of a warmer [pb_glossary id=\"757\"]climate[\/pb_glossary] following the late [pb_glossary id=\"1261\"]Proterozoic[\/pb_glossary] [pb_glossary id=\"1988\"]glacial[\/pb_glossary] environments, better preservation and fossilization of hard parts, or artifacts of a more complete and recent rock record. For example, fauna may have been diverse during the [pb_glossary id=\"1268\"]Ediacaran[\/pb_glossary]\u00a0[pb_glossary id=\"1244\"]Period[\/pb_glossary], setting the state for the [pb_glossary id=\"1272\"]Cambrian Explosion[\/pb_glossary], but they lacked hard body parts and would have left few [pb_glossary id=\"1228\"]fossils[\/pb_glossary] behind<\/span><span style=\"font-weight: 400\">. Regardless, during the [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary] 541\u2013485 million years ago marked the appearance of most animal phyla<\/span><span style=\"font-weight: 400\">. <\/span>\n\n[caption id=\"attachment_3313\" align=\"alignleft\" width=\"112\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Opabinia.jpg\"><img class=\"wp-image-564 size-medium\" title=\"&quot;Charles\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-112x300.jpg\" alt=\"The animal has a long trunk with claws at the end.\" width=\"112\" height=\"300\"><\/a> Original plate from Walcott's 1912 description of Opabinia, with labels: fp = frontal appendage, e = eye, ths = thoracic somites, i = intestine, ab = abdominal segment.[\/caption]\n\n<span style=\"font-weight: 400\">One of the best [pb_glossary id=\"1228\"]fossil[\/pb_glossary] sites for the [pb_glossary id=\"1272\"]Cambrian Explosion[\/pb_glossary] was discovered in 1909 by <a href=\"http:\/\/www.nasonline.org\/member-directory\/deceased-members\/20000936.html\">Charles Walcott (1850\u20131927)<\/a> in the <strong>Burgess [pb_glossary id=\"1917\"]Shale[\/pb_glossary]<\/strong> in western Canada. The Burgess [pb_glossary id=\"1917\"]Shale[\/pb_glossary] is a <strong>[pb_glossary id=\"1273\"]Lagerst\u00e4tte[\/pb_glossary]<\/strong>, a site of exceptional [pb_glossary id=\"1228\"]fossil[\/pb_glossary] preservation that includes impressions of soft body parts. This discovery allowed scientists to study [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] animals in immense detail because soft body parts are not normally preserved and fossilized. Other [pb_glossary id=\"1273\"]Lagerst\u00e4tte[\/pb_glossary] sites of similar age in China and Utah have allowed scientist to form a detailed picture of [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] biodiversity. The biggest mystery surrounds animals that do not fit existing lineages and are unique to that time. This includes many famous fossilized creatures: the first compound-eyed trilobites; <em>Wiwaxia<\/em>, a creature covered in spiny [pb_glossary id=\"1669\"]plates[\/pb_glossary];<em> Hallucigenia<\/em>, a walking worm with spikes;<em> Opabinia<\/em>, a five-eyed arthropod with a grappling claw; and <em>Anomalocaris<\/em>, the alpha predator of its time, complete with grasping appendages and circular [pb_glossary id=\"1776\"]mouth[\/pb_glossary] with sharp [pb_glossary id=\"1669\"]plates[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. <\/span>Most notably appearing during the [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] is an important ancestor to humans. A segmented worm called <em>Pikaia<\/em> is thought to be the earliest ancestor of the <strong>[pb_glossary id=\"1274\"]Chordata[\/pb_glossary]<\/strong> phylum that includes [pb_glossary id=\"1274\"]vertebrates[\/pb_glossary], animals with backbones<span style=\"font-weight: 400\">.\u00a0<\/span>\n\n[caption id=\"attachment_3314\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Coral_Outcrop_Flynn_Reef-1.jpg\"><img class=\"size-medium wp-image-565\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-300x225.jpg\" alt=\"The reef has many intricacies.\" width=\"300\" height=\"225\"><\/a> A modern coral reef.[\/caption]\n\n&nbsp;\n\nBy the end of the [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary], mollusks, brachiopods, nautiloids, gastropods, graptolites, echinoderms, and trilobites covered the sea floor. Although most animal phyla appeared by the [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary], the biodiversity at the family, genus, and species level was low until the [pb_glossary id=\"1277\"]Ordovician[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary]. During the <strong>Great [pb_glossary id=\"1277\"]Ordovician[\/pb_glossary] Biodiversification Event<\/strong>, [pb_glossary id=\"1274\"]vertebrates[\/pb_glossary] and invertebrates (animals without backbone) became more diverse and complex at family, genus, and species level. The cause of the rapid speciation event is still debated but some likely causes are a combination of warm temperatures, expansive [pb_glossary id=\"1653\"]continental[\/pb_glossary] shelves near the equator, and more [pb_glossary id=\"228\"]volcanism[\/pb_glossary] along the [pb_glossary id=\"1708\"]mid-ocean ridges[\/pb_glossary]. Some have shown evidence that an asteroid breakup event and consequent heavy [pb_glossary id=\"1254\"]meteorite[\/pb_glossary] impacts correlate with this diversification event. The additional [pb_glossary id=\"228\"]volcanism[\/pb_glossary] added nutrients to ocean water helping support a robust ecosystem. Many life forms and ecosystems that would be recognizable in current times appeared at this time. Mollusks, corals, and arthropods in particular multiplied to dominate the oceans<span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3315\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Guadalupe_Nima2.jpg\"><img class=\"wp-image-566 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-300x206.jpg\" alt=\"The entire mountain is one big fossil.\" width=\"300\" height=\"206\"><\/a> Guadalupe National Park is made of a giant fossil reef.[\/caption]\n\nOne important evolutionary advancement during the [pb_glossary id=\"1277\"]Ordovician[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary] was [pb_glossary id=\"1976\"]reef[\/pb_glossary]-building organisms, mostly colonial coral. Corals took advantage of the ocean chemistry, using [pb_glossary id=\"970\"]calcite[\/pb_glossary] to build large structures that resembled modern [pb_glossary id=\"1976\"]reefs[\/pb_glossary] like the Great Barrier [pb_glossary id=\"1976\"]Reef[\/pb_glossary] off the coast of Australia. These reefs housed thriving ecosystems of organisms that swam around, hid in, and crawled over them. Reefs are important to paleontologists because of their preservation potential, [pb_glossary id=\"985\"]massive[\/pb_glossary] size, and in-place ecosystems. Few other [pb_glossary id=\"1228\"]fossils[\/pb_glossary] offer more diversity and complexity than [pb_glossary id=\"1976\"]reef[\/pb_glossary] assemblages<span style=\"font-weight: 400\">.<\/span>\n\n<span style=\"font-weight: 400\">According to evidence from [pb_glossary id=\"1988\"]glacial[\/pb_glossary] deposits,\u00a0 a small [pb_glossary id=\"747\"]ice age[\/pb_glossary] caused sea-levels to drop and led to a major [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] by the end of the [pb_glossary id=\"1277\"]Ordovician[\/pb_glossary]. This is the earliest of five <strong>[pb_glossary id=\"1275\"]mass extinction[\/pb_glossary]<\/strong> events documented in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record. During this [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary], an unusually large number of species abruptly disappear in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record (see video).\u00a0<\/span>\n\n<span style=\"font-weight: 400\">Life bounced back during the [pb_glossary id=\"1278\"]Silurian[\/pb_glossary] [pb_glossary id=\"1244\"]period[\/pb_glossary]<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\">\u00a0The major evolutionary event was the development of the forward pair of gill arches into jaws, allowing fish new feeding strategies and opening up new ecological niches.<\/span>\n\n[caption id=\"attachment_4253\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/How-Many-Mass-Extinctions-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-567\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/aO9mOAKXvJs[\/embed]\n\n<em>3-minute video describing [pb_glossary id=\"1275\"]<em>mass extinctions<\/em>[\/pb_glossary] and how they are\u00a0defined.<\/em>\n\n[caption id=\"attachment_3316\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Placoderm.jpg\"><img class=\"wp-image-568 size-medium\" title=\"By User:Haplochromis (Self-photographed) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABothriolepis_panderi.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Placoderm-300x264.jpg\" alt=\"This fish is covered with armor.\" width=\"300\" height=\"264\"><\/a> The placoderm Bothriolepis panderi from the Devonian of Russia[\/caption]<span style=\"font-weight: 400\">Life bounced back during the [pb_glossary id=\"1278\"]Silurian[\/pb_glossary] [pb_glossary id=\"1244\"]period[\/pb_glossary]. The [pb_glossary id=\"1244\"]period[\/pb_glossary]\u2019s major evolutionary event was the development of jaws from the forward pair of gill arches in bony fishes and sharks. Hinged jaws allowed fish to exploit new food sources and ecological niches. This [pb_glossary id=\"1244\"]period[\/pb_glossary] also included the start of armored fishes, known as the placoderms. In addition to fish and jaws, [pb_glossary id=\"1278\"]Silurian[\/pb_glossary] rocks provide the first evidence of [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] or land-dwelling plants and animals<\/span><span style=\"font-weight: 400\">. The first vascular plant, <em>Cooksonia,<\/em> had woody tissues, [pb_glossary id=\"2194\"]pores[\/pb_glossary] for gas exchange, and veins for water and food transport<\/span><span style=\"font-weight: 400\">. Insects, spiders, scorpions, and crustaceans began to inhabit moist, freshwater [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] environments<\/span><span style=\"font-weight: 400\">. \u00a0<\/span>\n\n[caption id=\"attachment_3317\" align=\"alignleft\" width=\"392\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fishapods.png\"><img class=\"wp-image-569\" title=\"By Graphic by dave souza, incorporating images by others, as description (Own work by uploader using commons sources) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0-3.0-2.5-2.0-1.0&quot;>CC BY-SA 4.0-3.0-2.5-2.0-1.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFishapods.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fishapods-300x153.png\" alt=\"Six different fish\/amphibians are shown, with variation between totally swimming and fully walking.\" width=\"392\" height=\"200\"><\/a> Several different types of fish and amphibians that led to walking on land.[\/caption]<span style=\"font-weight: 400\">The [pb_glossary id=\"1279\"]Devonian[\/pb_glossary] [pb_glossary id=\"1244\"]Period[\/pb_glossary] is called the Age of Fishes due to the rise in plated, jawed, and lobe-finned fishes . The lobe-finned fishes, which were related to the modern lungfish and coelacanth, are important for their eventual evolution into tetrapods, four-limbed [pb_glossary id=\"1274\"]vertebrate[\/pb_glossary] animals that can walk on land. \u00a0The first lobe-finned land-walking fish, named <em>Tiktaalik<\/em>, appeared about 385 million years ago and serves as a transition [pb_glossary id=\"1228\"]fossil[\/pb_glossary] between fish and early tetrapods<\/span><span style=\"font-weight: 400\">. <\/span>Though Tiktaalik was clearly a fish, it had some tetrapod structures as well. Several [pb_glossary id=\"1228\"]fossils[\/pb_glossary] from the [pb_glossary id=\"1279\"]Devonian[\/pb_glossary] are more tetrapod like than fish like but these weren\u2019t fully [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary]. The first fully [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] tetrapod arrived in the Mississippian (early [pb_glossary id=\"475\"]Carboniferous[\/pb_glossary]) [pb_glossary id=\"1244\"]period[\/pb_glossary]. By the Mississippian (early [pb_glossary id=\"475\"]Carboniferous[\/pb_glossary]) [pb_glossary id=\"1244\"]period[\/pb_glossary], tetrapods had evolved into two main groups, amphibians and amniotes, from a common tetrapod ancestor. The amphibians were able to breathe air and live on land but still needed water to nurture their soft eggs. The first reptile (an amniote) could live and reproduce entirely on land with hard-shelled eggs that wouldn\u2019t dry out.\n\n<span style=\"font-weight: 400\">\u00a0Land plants had also evolved into the first trees and forests<\/span><span style=\"font-weight: 400\">. Toward the end of the [pb_glossary id=\"1279\"]Devonian[\/pb_glossary], another [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] event occurred. This [pb_glossary id=\"755\"]extinction[\/pb_glossary], while severe, is the least temporally defined, with wide variations in the timing of the event or events. [pb_glossary id=\"1976\"]Reef[\/pb_glossary] building organisms were the hardest hit, leading to dramatic changes in [pb_glossary id=\"1961\"]marine[\/pb_glossary] ecosystems<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3318\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Arthropleura.png\"><img class=\"wp-image-570 size-medium\" title=\"By Tim Bertelink (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArthropleura.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Arthropleura-300x156.png\" alt=\"The millipede is about 2 meters long.\" width=\"300\" height=\"156\"><\/a> A reconstruction of the giant arthropod (insects and their relatives) Arthropleura.[\/caption]<span style=\"font-weight: 400\">The next time [pb_glossary id=\"1244\"]period[\/pb_glossary], called the [pb_glossary id=\"475\"]Carboniferous[\/pb_glossary] (North American geologists have subdivided this into the Mississippian and Pennsylvanian [pb_glossary id=\"1244\"]periods[\/pb_glossary]), saw the highest levels of oxygen ever known, with forests (e.g., ferns, club mosses) and swamps dominating the landscape <\/span><span style=\"font-weight: 400\">. This helped cause\u00a0the largest arthropods ever<\/span><span style=\"font-weight: 400\">, like the millipede <\/span><i><span style=\"font-weight: 400\">Arthropleura<\/span><\/i><span style=\"font-weight: 400\">, at 2.5 meters (6.4 feet) long! It also saw the rise of a new group of animals, the reptiles. The evolutionary advantage that reptiles have over amphibians is the amniote egg (egg with a protective shell), which allows them to rely on non-aquatic environments for reproduction. This widened the [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] reach of reptiles compared to amphibians. This booming life, especially plant life, created cooling temperatures as carbon dioxide<\/span><span style=\"font-weight: 400\">\u00a0was removed from the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. By the middle [pb_glossary id=\"475\"]Carboniferous[\/pb_glossary], these cooler temperatures led to an [pb_glossary id=\"747\"]ice age[\/pb_glossary] (called the Karoo [pb_glossary id=\"747\"]Glaciation[\/pb_glossary]) and less-productive forests. The reptiles fared much better than the amphibians, leading to their diversification<\/span><span style=\"font-weight: 400\">. This [pb_glossary id=\"1988\"]glacial[\/pb_glossary] event lasted into the early [pb_glossary id=\"476\"]Permian[\/pb_glossary]<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3319\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dimetrodon_grandis.jpg\"><img class=\"wp-image-571 size-medium\" title=\"<a href=&quot;https:\/\/en.wikipedia.org\/wiki\/User:DiBgd&quot; class=&quot;extiw&quot; title=&quot;wikipedia:User:DiBgd&quot;>DiBgd<\/a> at <a href=&quot;https:\/\/en.wikipedia.org\/wiki\/&quot; class=&quot;extiw&quot; title=&quot;wikipedia:&quot;>English Wikipedia<\/a> [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>, <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by\/2.5&quot;>CC BY 2.5<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADimetrodon_grandis.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dimetrodon_grandis-300x169.jpg\" alt=\"The animal has a large mouth with sharp teeth and a large sail on its back.\" width=\"300\" height=\"169\"><\/a> Reconstruction of Dimetrodon.[\/caption]<span style=\"font-weight: 400\">By the [pb_glossary id=\"476\"]Permian[\/pb_glossary], with [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] assembled, the [pb_glossary id=\"1701\"]supercontinent[\/pb_glossary] led to a dryer [pb_glossary id=\"757\"]climate[\/pb_glossary], and even more diversification and domination by the reptiles<\/span><span style=\"font-weight: 400\">. The groups that developed in this warm [pb_glossary id=\"757\"]climate[\/pb_glossary] eventually radiated into dinosaurs. Another group, known as the synapsids, eventually evolved into mammals<\/span><span style=\"font-weight: 400\">. Synapsids, including the famous sail-backed <\/span><i><span style=\"font-weight: 400\">Dimetrodon<\/span><\/i><span style=\"font-weight: 400\"> are commonly confused with dinosaurs.<\/span><span style=\"font-weight: 400\">\u00a0Pelycosaurs (of the Pennsylvanian to early [pb_glossary id=\"476\"]Permian[\/pb_glossary] like <\/span><i><span style=\"font-weight: 400\">Dimetrodon) <\/span><\/i><span style=\"font-weight: 400\">are the first group of synapsids that exhibit the beginnings of mammalian characteristics such as well-differentiated dentition: incisors, highly developed canines in lower and upper jaws and cheek teeth, premolars and molars. Starting in the late [pb_glossary id=\"476\"]Permian[\/pb_glossary], a second group of synapsids, called the therapsids (or mammal-like reptiles) evolve<\/span><span style=\"font-weight: 400\">, and become the ancestors to mammals.<\/span>\n<h4><span style=\"font-weight: 400\">Permian Mass Extinction<\/span><\/h4>\n[caption id=\"attachment_2911\" align=\"alignright\" width=\"399\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/World-map-or-flood-basalts.jpg\"><img class=\"wp-image-307\" title=\"By Williamborg [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFlood_Basalt_Map.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/World-map-or-flood-basalts-300x168.jpg\" alt=\"World map of flood basalts. Note the largest is the Siberian Traps\" width=\"399\" height=\"223\"><\/a> World map of flood basalts. Note the largest is the Siberian Traps[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">The end of the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]era[\/pb_glossary] is marked by the largest [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] in earth history. The [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]era[\/pb_glossary] had two smaller [pb_glossary id=\"1275\"]mass extinctions[\/pb_glossary], \u00a0but these were not as large as the <\/span><b>[pb_glossary id=\"477\"]Permian Mass Extinction[\/pb_glossary]<\/b><span style=\"font-weight: 400\">, also known as the <\/span>[pb_glossary id=\"477\"]Permian-Triassic Extinction Event[\/pb_glossary]<span style=\"font-weight: 400\">. It is estimated that up to 96% of [pb_glossary id=\"1961\"]marine[\/pb_glossary] species and 70% of land-dwelling ([pb_glossary id=\"1980\"]terrestrial[\/pb_glossary]) [pb_glossary id=\"1274\"]vertebrates[\/pb_glossary] went extinct<\/span><span style=\"font-weight: 400\">. Many famous organisms, like sea scorpions and trilobites, were never seen again in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record. <\/span><span style=\"font-weight: 400\">What caused such a widespread [pb_glossary id=\"755\"]extinction[\/pb_glossary] event? The exact cause is still debated, though the leading idea relates to extensive [pb_glossary id=\"228\"]volcanism[\/pb_glossary] associated with the <strong>Siberian [pb_glossary id=\"2420\"]Traps[\/pb_glossary]<\/strong>, which are one of the largest deposits of [pb_glossary id=\"244\"]flood basalts[\/pb_glossary] known on Earth, dating to the time of the [pb_glossary id=\"755\"]extinction[\/pb_glossary] event<\/span><span style=\"font-weight: 400\">. The eruption size is estimated at over 3 million cubic kilometers<\/span><span style=\"font-weight: 400\"> that is approximately 4,000,000 times larger than the famous 1980 Mt. St. Helens eruption in Washington. \u00a0The unusually large [pb_glossary id=\"228\"]volcanic[\/pb_glossary] eruption would have contributed a large amount of toxic gases, aerosols, and greenhouse gasses into the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]. Further, some evidence suggests that the [pb_glossary id=\"228\"]volcanism[\/pb_glossary] burned vast [pb_glossary id=\"1934\"]coal[\/pb_glossary] deposits releasing methane (a greenhouse gas) into the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. As discussed in <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/15-global-climate-change\/\">Chapter 15<\/a>, greenhouse gases cause the [pb_glossary id=\"757\"]climate[\/pb_glossary] to warm. This extensive addition of greenhouse gases from the Siberian [pb_glossary id=\"2420\"]Traps[\/pb_glossary] may have caused a runaway [pb_glossary id=\"762\"]greenhouse effect[\/pb_glossary] that rapidly changed the [pb_glossary id=\"757\"]climate[\/pb_glossary], acidified the oceans, disrupted food chains, disrupted carbon cycling, and caused the largest [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary]<\/span><span style=\"font-weight: 400\">.<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"53\"]\n\n[caption id=\"attachment_4248\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Video-QR-Code.png\"><img class=\"size-thumbnail wp-image-572\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this interactive activity via this QR Code.[\/caption]\n<h2><b>8.7 Phanerozoic Eon: Mesozoic Era<\/b><\/h2>\n[caption id=\"attachment_3321\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fighting_dinosaurs.jpg\"><img class=\"wp-image-573 size-medium\" title=\"By Yuya Tamai from Gifu, Japan (2014-03-25 13.04.52) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by\/2.0&quot;>CC BY 2.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFighting_dinosaurs_(1).jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fighting_dinosaurs-300x173.jpg\" alt=\"The dinosaurs are fighting\" width=\"300\" height=\"173\"><\/a> Perhaps the greatest fossil ever found, a velociraptor attacked a protoceratops, and both were fossilized mid sequence.[\/caption]<span style=\"font-weight: 400\">Following the [pb_glossary id=\"477\"]Permian Mass Extinction[\/pb_glossary], the <strong>[pb_glossary id=\"479\"]Mesozoic[\/pb_glossary]<\/strong> (\"middle life\") was from 252 million years ago to 66 million years ago. As [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] started to break apart, mammals, birds, and flowering plants developed. The [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] is probably best known as the age of reptiles, most notably, the dinosaurs.<\/span>\n<h3><span style=\"font-weight: 400\">8.7.1 Mesozoic Tectonics and Paleogeography<\/span><\/h3>\n[caption id=\"attachment_3322\" align=\"alignleft\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pangea_animation_03.gif\"><img class=\"size-full wp-image-574\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangea_animation_03.gif\" alt=\"The continents separate into their current configuration.\" width=\"200\" height=\"160\"><\/a> Animation showing Pangea breaking up[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"2444\"]Pangea[\/pb_glossary] started breaking up (in a region that would become eastern Canada and United States) around 210 \u00a0million years ago in the Late [pb_glossary id=\"485\"]Triassic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Clear evidence for this includes the age of the [pb_glossary id=\"1756\"]sediments[\/pb_glossary] in the Newark Supergroup [pb_glossary id=\"1702\"]rift[\/pb_glossary] basins and the Palisades [pb_glossary id=\"1022\"]sill[\/pb_glossary] of the eastern part of North America and the age of the Atlantic [pb_glossary id=\"1963\"]ocean floor[\/pb_glossary]. Due to sea-floor spreading, the oldest rocks on the Atlantic\u2019s floor are along the [pb_glossary id=\"1968\"]coast[\/pb_glossary] of northern Africa and the east coast of \u00a0North America, while the youngest are along the [pb_glossary id=\"1708\"]mid-ocean ridge[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3323\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/age_oceanic_lith.jpg\"><img class=\"wp-image-3323 size-medium\" title=\"Image via NOAA https:\/\/www.ngdc.noaa.gov\/mgg\/ocean_age\/data\/2008\/image\/age_oceanic_lith.jpg\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/age_oceanic_lith-1.jpg\" alt=\"The map shoes colors that represent different ages.\" width=\"300\" height=\"191\"><\/a> Age of oceanic lithosphere, in millions of years. Notice the differences in the Atlantic Ocean along the coasts of the continents.[\/caption]\n\n<span style=\"font-weight: 400\">This age pattern shows how the Atlantic Ocean opened as the young Mid-Atlantic Ridge began to create the seafloor. This means the Atlantic ocean started opening and was first formed here. The southern Atlantic opened next, with South America separating from central and southern Africa. Last (happening after the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] ended) was the northernmost Atlantic, with Greenland and Scandinavia parting ways.\u00a0<\/span><span style=\"font-weight: 400\">The breaking points of each [pb_glossary id=\"1702\"]rifted[\/pb_glossary] [pb_glossary id=\"1669\"]plate[\/pb_glossary] margin eventually turned into the passive [pb_glossary id=\"1669\"]plate[\/pb_glossary] boundaries of the east [pb_glossary id=\"1968\"]coast[\/pb_glossary] of the Americas today.<\/span>\n\n[caption id=\"attachment_4248\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Video-QR-Code.png\"><img class=\"size-thumbnail wp-image-572\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this interactive activity via this QR Code.[\/caption]\n\n[video width=\"300\" height=\"200\" mp4=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/PangeaEADef.mp4\"][\/video]\n\n<em><a href=\"http:\/\/emvc.geol.ucsb.edu\/2_infopgs\/IP1GTect\/aPangeaAnim.html\">Video<\/a> of [pb_glossary id=\"2444\"]<em>Pangea<\/em>[\/pb_glossary] breaking apart and [pb_glossary id=\"1669\"]<em>plates<\/em>[\/pb_glossary] moving to their present locations. By Tanya Atwater.<\/em>\n\n[caption id=\"attachment_3324\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sevierorogeny.jpg\"><img class=\"wp-image-576 size-medium\" title=\"By Pinkcorundum (Own work) [<a href=&quot;http:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en&quot;>CC0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASevierorogeny.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Sevierorogeny-300x113.jpg\" alt=\"It shows faulting and a volcanic arc\" width=\"300\" height=\"113\"><\/a> Sketch of the major features of the Sevier Orogeny.[\/caption]<span style=\"font-weight: 400\">In western North America, an active [pb_glossary id=\"1669\"]plate[\/pb_glossary] margin had started with [pb_glossary id=\"1680\"]subduction[\/pb_glossary], controlling most of the [pb_glossary id=\"1654\"]tectonics[\/pb_glossary] of that region in the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary]. Another possible island-[pb_glossary id=\"1687\"]arc[\/pb_glossary] [pb_glossary id=\"1698\"]collision[\/pb_glossary] created the Sonoman [pb_glossary id=\"1663\"]Orogeny[\/pb_glossary] in Nevada during the latest [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] to the [pb_glossary id=\"485\"]Triassic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. In the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary], another island-[pb_glossary id=\"1687\"]arc[\/pb_glossary] [pb_glossary id=\"1698\"]collision[\/pb_glossary] caused the Nevadan [pb_glossary id=\"1663\"]Orogeny[\/pb_glossary], a large Andean-style [pb_glossary id=\"1695\"]volcanic arc[\/pb_glossary] and thrust belt<\/span><span style=\"font-weight: 400\">. The Sevier Orogeny followed in the Cretaceous, which was mainly a volcanic arc to the west and a thin-skinned fold and thrust belt to the east<\/span><span style=\"font-weight: 400\">, meaning stacks of shallow [pb_glossary id=\"2143\"]faults[\/pb_glossary] and [pb_glossary id=\"502\"]folds[\/pb_glossary] built up the topography. Many of the structures in the Rocky Mountains today date from this [pb_glossary id=\"1663\"]orogeny[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3325\" align=\"alignright\" width=\"250\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cretaceous_seaway.png\"><img class=\"wp-image-577 size-full\" title=\"USGS, public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Cretaceous_seaway.png\" alt=\"Water is covering the middle of North America.\" width=\"250\" height=\"301\"><\/a> The Cretaceous Interior Seaway in the mid-Cretaceous.[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1654\"]Tectonics[\/pb_glossary] had an influence in one more important geographic feature in North America: the [pb_glossary id=\"487\"]Cretaceous[\/pb_glossary] Western Interior Foreland [pb_glossary id=\"508\"]Basin[\/pb_glossary], which flooded during high sea levels forming the <strong>[pb_glossary id=\"480\"]Cretaceous\u00a0Interior Seaway[\/pb_glossary]<\/strong>. [pb_glossary id=\"1680\"]Subduction[\/pb_glossary] from the west was the Farallon [pb_glossary id=\"1669\"]Plate[\/pb_glossary], an [pb_glossary id=\"1659\"]oceanic[\/pb_glossary] [pb_glossary id=\"1669\"]plate[\/pb_glossary] connected to the Pacific [pb_glossary id=\"1669\"]Plate[\/pb_glossary] (seen today as remnants such as the Juan de Fuca [pb_glossary id=\"1669\"]Plate[\/pb_glossary], off the [pb_glossary id=\"1968\"]coast[\/pb_glossary] of the Pacific Northwest). [pb_glossary id=\"1680\"]Subduction[\/pb_glossary] was shallow at this time because a very young, hot and less dense portion of the Farallon [pb_glossary id=\"1669\"]plate[\/pb_glossary] was [pb_glossary id=\"1680\"]subducted[\/pb_glossary]. This shallow [pb_glossary id=\"1680\"]subduction[\/pb_glossary] caused a downwarping in the central part of North America<\/span><span style=\"font-weight: 400\">. High sea levels due to shallow [pb_glossary id=\"1680\"]subduction[\/pb_glossary], and increasing rates of seafloor spreading and [pb_glossary id=\"1680\"]subduction[\/pb_glossary], high temperatures, and melted ice also contributed to the high sea levels<\/span><span style=\"font-weight: 400\">. These factors allowed a shallow epicontinental seaway that extended from the Gulf of Mexico to the Arctic Ocean to divide North America into two separate land masses<\/span><span style=\"font-weight: 400\">, Laramidia to the west and Appalachia to the east, for 25 million years<\/span><span style=\"font-weight: 400\">. Many of the [pb_glossary id=\"1934\"]coal[\/pb_glossary] deposits in Utah and Wyoming formed from swamps along the shores of this seaway<\/span><span style=\"font-weight: 400\">. By the end of the [pb_glossary id=\"487\"]Cretaceous[\/pb_glossary], cooling temperatures caused the seaway to regress<\/span><span style=\"font-weight: 400\">.<\/span>\n<h3><span style=\"font-weight: 400\">8.7.2 Mesozoic Evolution<\/span><\/h3>\n[caption id=\"attachment_3326\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Mesozoic_Scene.jpg\"><img class=\"wp-image-578 size-medium\" title=\"By Gerhard Boeggemann (File was sent by Gerhard Boeggemann. Gallery) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.5&quot;>CC BY-SA 2.5<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEuropasaurus_holgeri_Scene_2.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Mesozoic_Scene-300x225.jpg\" alt=\"Several dinosaurs and their relatives are in the scene.\" width=\"300\" height=\"225\"><\/a> A Mesozoic scene from the late Jurassic.[\/caption]<span style=\"font-weight: 400\">The [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] [pb_glossary id=\"1243\"]era[\/pb_glossary] is dominated by reptiles, and more specifically, the dinosaurs. The [pb_glossary id=\"485\"]Triassic[\/pb_glossary] saw devastated ecosystems that took over 30 million years to fully re-emerge after the [pb_glossary id=\"477\"]Permian Mass Extinction[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. \u00a0The first appearance of many modern groups of animals that would later flourish occurred at this time. \u00a0This includes frogs (amphibians), turtles (reptiles), [pb_glossary id=\"1961\"]marine[\/pb_glossary] ichthyosaurs and plesiosaurs ([pb_glossary id=\"1961\"]marine[\/pb_glossary] reptiles), mammals, and the archosaurs. \u00a0The archosaurs (\u201cruling reptiles\u201d) include ancestral groups that went [pb_glossary id=\"755\"]extinct[\/pb_glossary] at the end of the [pb_glossary id=\"485\"]Triassic[\/pb_glossary], as well as the flying pterosaurs, crocodilians, and the dinosaurs. \u00a0Archosaurs, like the placental mammals after them, occupied all major environments: [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] (dinosaurs), in the air (pterosaurs), aquatic (crocodilians) and even fully [pb_glossary id=\"1961\"]marine[\/pb_glossary] habitats ([pb_glossary id=\"1961\"]marine[\/pb_glossary] crocodiles). The pterosaurs, the first [pb_glossary id=\"1274\"]vertebrate[\/pb_glossary]\u00a0group to take flight, like the dinosaurs and mammals, start small in the [pb_glossary id=\"485\"]Triassic[\/pb_glossary].<\/span>\n\n[caption id=\"attachment_3327\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Augustasaurus_BW.jpg\"><img class=\"wp-image-579 size-medium\" title=\"By Nobu Tamura (http:\/\/spinops.blogspot.com) (Own work) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by\/3.0&quot;>CC BY 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AAugustasaurus_BW.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Augustasaurus_BW-300x189.jpg\" alt=\"It is a swimming reptile with a long neck\" width=\"300\" height=\"189\"><\/a> A drawing of the early plesiosaur Agustasaurus from the Triassic of Nevada.[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">At the end of the [pb_glossary id=\"485\"]Triassic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">, another [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] event occurred, the fourth major [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] in the geologic record. This was perhaps caused by the Central Atlantic Magmatic Province [pb_glossary id=\"244\"]flood basalt[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. The end-[pb_glossary id=\"485\"]Triassic[\/pb_glossary] [pb_glossary id=\"755\"]extinction[\/pb_glossary] made certain lineages go extinct and helped spur the evolution of survivors like mammals, pterosaurs (flying reptiles), ichthyosaurs\/plesiosaurs\/mosasaurs ([pb_glossary id=\"1961\"]marine[\/pb_glossary] reptiles), and dinosaurs<\/span><span style=\"font-weight: 400\">. <\/span>\n\n[caption id=\"attachment_3328\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Megazostrodon_sp._Natural_History_Museum_-_London.jpg\"><img class=\"wp-image-580 size-medium\" title=\"By Theklan (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AMegazostrodon_sp._Natural_History_Museum_-_London.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Megazostrodon_sp._Natural_History_Museum_-_London-300x200.jpg\" alt=\"It is small, less than 5 inches, and looks like a shrew\" width=\"300\" height=\"200\"><\/a> Reconstruction of the small (&lt;5\") Megazostrodon, one of the first animals considered to be a true mammal.[\/caption]<span style=\"font-weight: 400\">Mammals, as previously mentioned, got their start from a reptilian synapsid ancestor possibly in the late [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Mammals stayed small, in mainly nocturnal niches, with insects being their largest prey. The development of warm-blooded circulation and fur may have been a response to this lifestyle<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3329\" align=\"alignright\" width=\"226\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ornithischia.png\"><img class=\"wp-image-581\" title=\"By User:Fredrik (en:User:Fredrik) [<a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a> or <a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;>CC-BY-SA-3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AOrnithischia.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ornithischia-150x150.png\" alt=\"The bones of the pubis and ischium are close to each other.\" width=\"226\" height=\"186\"><\/a> Closed structure of a ornithischian hip, which is similar to a birds.[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">In the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary], species that were previously common, flourished due to a warmer and more tropical [pb_glossary id=\"757\"]climate[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. The dinosaurs were relatively small animals in the [pb_glossary id=\"485\"]Triassic[\/pb_glossary] [pb_glossary id=\"1244\"]period[\/pb_glossary] of the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary], but became truly [pb_glossary id=\"985\"]massive[\/pb_glossary] in the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary]. \u00a0Dinosaurs are split into two groups based on their hip structure<\/span><span style=\"font-weight: 400\">, i.e. orientation of the pubis and ischium bones in relationship to each other. \u00a0This is referred to as the \u201creptile hipped\u201d saurischians and the \u201cbird hipped\u201d ornithischians. This has recently been brought into question by a new idea for dinosaur lineage.<\/span>\n\n[caption id=\"attachment_3330\" align=\"alignleft\" width=\"227\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Saurischia.png\"><img class=\"wp-image-582\" title=\"By Fred the Oyster [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASaurischia_pelvis_structure.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Saurischia.png\" alt=\"The bones of the pubis and ischium are away from each other.\" width=\"227\" height=\"214\"><\/a> Open structure of a saurischian hip, which is similar to a lizards.[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">Most of the dinosaurs of the [pb_glossary id=\"485\"]Triassic[\/pb_glossary] were saurischians, but all of them were bipedal. The major adaptive advantage dinosaurs had was changes in the hip and ankle bones, tucking the legs under the body for improved locomotion as opposed to the semi-erect gait of crocodiles or the sprawling posture of reptiles. In the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary], limbs (or a lack thereof) were also important to another group of reptiles, leading to the evolution of <\/span><i><span style=\"font-weight: 400\">Eophis<\/span><\/i><span style=\"font-weight: 400\">, the oldest snake<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3331\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Beipiao1mmartyniuk.png\"><img class=\"wp-image-583 size-medium\" title=\"By Matt Martyniuk (Dinoguy2) (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABeipiao1mmartyniuk.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Beipiao1mmartyniuk-300x158.png\" alt=\"It is a feathered dinosaur with large hand claws\" width=\"300\" height=\"158\"><\/a> Therizinosaurs, like Beipiaosaurus (shown in this restoration), are known for their enormous hand claws.[\/caption]<span style=\"font-weight: 400\">There is a paucity of dinosaur [pb_glossary id=\"1228\"]fossils[\/pb_glossary] from the Early and Middle [pb_glossary id=\"486\"]Jurassic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">, but by the Late [pb_glossary id=\"486\"]Jurassic[\/pb_glossary] they were dominating the planet<\/span><span style=\"font-weight: 400\">. The saurischians diversified into the giant herbivorous (plant-eating) long-necked sauropods weighing up to 100 tons and bipedal carnivorous theropods, with the possible exception of the <\/span><i><span style=\"font-weight: 400\">Therizinosaurs<\/span><\/i><span style=\"font-weight: 400\">. All of the ornithischians (e.g <\/span><i><span style=\"font-weight: 400\">Stegosaurus, Iguanodon, Triceratops, Ankylosaurus,\u00a0<\/span><\/i><i>Pachycephhlosaurus<\/i>) were herbivorous with a strong tendency to have a \u201cturtle-like\u201d beak at the tips of their mouths.\n\n[caption id=\"attachment_2488\" align=\"alignleft\" width=\"222\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Archaeopteryx_lithographica_Berlin_specimen.jpg\"><img class=\"wp-image-54 size-medium\" title=\"By H. Raab (User: Vesta) (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;>CC BY-SA 3.0<\/a> or <a href=&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;>GFDL<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArchaeopteryx_lithographica_(Berlin_specimen).jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archaeopteryx_lithographica_Berlin_specimen-222x300.jpg\" alt=\"The fossil has bird and dinosaur features.\" width=\"222\" height=\"300\"><\/a> Iconic \u201cBerlin specimen\u201d Archaeopteryx lithographica fossil from Germany.[\/caption]&nbsp;\n\n<span style=\"font-weight: 400\">The pterosaurs grew and diversified in the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary], and another notable arial organism developed and thrived in the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary]: birds. When <\/span><i><span style=\"font-weight: 400\">Archeopteryx<\/span><\/i><span style=\"font-weight: 400\"> was found in the Solnhofen [pb_glossary id=\"1273\"]Lagerst\u00e4tte[\/pb_glossary] of Germany<\/span><span style=\"font-weight: 400\">, a seeming dinosaur-bird hybrid, it started the conversation on the origin of birds. The idea that birds evolved from dinosaurs occurred very early in the history of research into evolution, only a few years after Darwin\u2019s <\/span><i><span style=\"font-weight: 400\">On the Origin of Species<\/span><\/i><span style=\"font-weight: 400\">. This study used a remarkable [pb_glossary id=\"1228\"]fossil[\/pb_glossary] of <\/span><i><span style=\"font-weight: 400\">Archeopteryx<\/span><\/i><span style=\"font-weight: 400\"> from a transitional animal between dinosaurs and birds. Small meat-eating theropod dinosaurs were likely the branch that became birds due to their similar features<\/span><span style=\"font-weight: 400\">. A significant debate still exists over how and when powered flight evolved. Some have stated a running-start model<\/span><span style=\"font-weight: 400\">, while others have favored a tree-leaping gliding model<\/span><span style=\"font-weight: 400\"> or even a semi-combination: flapping to aid in climbing<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3333\" align=\"alignright\" width=\"199\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Argentinosaurus_DSC_2943.jpg\"><img class=\"wp-image-584 size-medium\" title=\"By Eva K. (Eva K.) [<a href=&quot;http:\/\/www.gnu.org\/licenses\/old-licenses\/fdl-1.2.html&quot;>GFDL 1.2<\/a> or <a href=&quot;http:\/\/artlibre.org\/licence\/lal\/en&quot;>FAL<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArgentinosaurus_DSC_2943.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Argentinosaurus_DSC_2943-199x300.jpg\" alt=\"The dinosaur is huge! 130' long and 24' high.\" width=\"199\" height=\"300\"><\/a> Reconstructed skeleton of Argentinosaurus, from Naturmuseum Senckenberg in Germany.[\/caption]<span style=\"font-weight: 400\">The [pb_glossary id=\"487\"]Cretaceous[\/pb_glossary] saw a further diversification, specialization, and domination of the dinosaurs and other fauna. One of the biggest changes on land was the transition to angiosperm-dominated flora. Angiosperms, which are plants with flowers and seeds, had originated in the [pb_glossary id=\"487\"]Cretaceous[\/pb_glossary]<\/span><span style=\"font-weight: 400\">, switching many plains to grasslands by the end of the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. By the end of the [pb_glossary id=\"1244\"]period[\/pb_glossary], they had replaced gymnosperms (evergreen trees) and ferns as the dominant plant in the world\u2019s forests. Haplodiploid eusocial insects (bees and ants) are descendants from [pb_glossary id=\"486\"]Jurassic[\/pb_glossary] wasp-like ancestors that co-evolved with the flowering plants during this time [pb_glossary id=\"1244\"]period[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. The breakup of [pb_glossary id=\"2444\"]Pangea[\/pb_glossary] not only shaped our modern world\u2019s geography, but biodiversity at the time as well. Throughout the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary], animals on the isolated, now separated island continents (formerly parts of [pb_glossary id=\"2444\"]Pangea[\/pb_glossary]), took strange evolutionary turns. This includes giant titanosaurian sauropods (<\/span><i><span style=\"font-weight: 400\">Argentinosaurus<\/span><\/i><span style=\"font-weight: 400\">) and theropods (<\/span><i><span style=\"font-weight: 400\">Giganotosaurus<\/span><\/i><span style=\"font-weight: 400\">) from South America<\/span><span style=\"font-weight: 400\">.<\/span>\n<h4><span style=\"font-weight: 400\">K-T Extinction<\/span><\/h4>\n[caption id=\"attachment_3334\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Extinction_intensity.svg_.png\"><img class=\"wp-image-585 size-medium\" title=\"After: Raup, D. &amp; Sepkoski, J. (1982). &quot;Mass extinctions in the marine fossil record&quot;. Science 215: 1501\u20131503. DOI:10.1126\/science.215.4539.1501. Rohde, R.A. &amp; Muller, R.A. (2005). &quot;Cycles in fossil diversity&quot;. Nature 434: 209-210. DOI:10.1038\/nature03339. Sepkoski, J. (2002) A Compendium of Fossil Marine Animal Genera (eds. Jablonski, D. &amp; Foote, M.) Bull. Am. Paleontol. no. 363 (Paleontological Research Institution, Ithaca, NY). Signor, P. and J. Lipps (1982) &quot;Sampling bias, gradual extinction patterns and catastrophes in the fossil record&quot;, in Geologic Implications of Impacts of Large Asteroids and Comets on the Earth, I. Silver and P. Silver Eds, Geol. Soc. Amer. Special Paper 190, Boulder Colo. p. 291-296.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-300x183.png\" alt=\"There are many spikes, but the K\/T spike is second largest to the end Perlman.\" width=\"300\" height=\"183\"><\/a> Graph of the rate of extinctions. Note the large spike at the end of the Cretaceous (labeled as K).[\/caption]\n\n<span style=\"font-weight: 400\">Similar to the end of the [pb_glossary id=\"1271\"]Paleozoic[\/pb_glossary] [pb_glossary id=\"1243\"]era[\/pb_glossary], the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] [pb_glossary id=\"1243\"]Era[\/pb_glossary] ended with the <\/span><b>K-Pg [pb_glossary id=\"1275\"]Mass Extinction[\/pb_glossary] <\/b><span style=\"font-weight: 400\">(previously known as the <\/span><b>[pb_glossary id=\"481\"]K-T Extinction[\/pb_glossary]<\/b><span style=\"font-weight: 400\">) 66 million years ago<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\"> This [pb_glossary id=\"755\"]extinction[\/pb_glossary] event was likely caused by a large <\/span><b>[pb_glossary id=\"482\"]bolide[\/pb_glossary] <\/b>(<span style=\"font-weight: 400\">an extraterrestrial impactor such as an asteroid, [pb_glossary id=\"1254\"]meteoroid[\/pb_glossary], or comet) that collided with earth<\/span><span style=\"font-weight: 400\">. Ninety percent of plankton species, 75% of plant species, and all the dinosaurs went [pb_glossary id=\"755\"]extinct[\/pb_glossary] at this time.<\/span>\n\n[caption id=\"attachment_3335\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Impact_event.jpg\"><img class=\"wp-image-586 size-medium\" title=\"By The original uploader was Fredrik at English Wikipedia [Public domain, Public domain or Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AImpact_event.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Impact_event-300x209.jpg\" alt=\"The rock is slamming into the Earth\" width=\"300\" height=\"209\"><\/a> Artist's depiction of an impact event[\/caption]<span style=\"font-weight: 400\">One of the strongest pieces of evidence comes from the [pb_glossary id=\"1778\"]element[\/pb_glossary] iridium. Quite rare on Earth, and more common in [pb_glossary id=\"1254\"]meteorites[\/pb_glossary], it has been found all over the world in higher concentrations at a particular layer of rock that formed at the time of the K-T boundary. Soon other scientists started to find evidence to back up the claim. Melted rock spheres<\/span><span style=\"font-weight: 400\">, a special type of \u201cshocked\u201d [pb_glossary id=\"967\"]quartz[\/pb_glossary] called stishovite, that only is found at impact sites, was found in many places around the world <\/span><span style=\"font-weight: 400\">. T<\/span><span style=\"font-weight: 400\">he huge impact created a strong thermal pulse that could be responsible for global forest fires<\/span><span style=\"font-weight: 400\">, strong acid rains<\/span><span style=\"font-weight: 400\">, a corresponding abundance of ferns, the first colonizing plants after a forest fire<\/span><span style=\"font-weight: 400\">, enough debris thrown into the air to significantly cool temperatures afterward<\/span><span style=\"font-weight: 400\">, and a 2-km high [pb_glossary id=\"2272\"]tsunami[\/pb_glossary] inferred from deposits found from Texas to Alabama<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3336\" align=\"alignleft\" width=\"268\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Chicxulub_radar_topography.jpg\"><img class=\"wp-image-587 size-medium\" title=\"By NASA\/JPL-Caltech [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AChicxulub_radar_topography.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Chicxulub_radar_topography-268x300.jpg\" alt=\"The crater is circular.\" width=\"268\" height=\"300\"><\/a> The land expression of the Chicxulub crater. The other side of the crater is within the Gulf of M\u00e9xico.[\/caption]<span style=\"font-weight: 400\">Still, with all this evidence, one large piece remained missing: the crater where the [pb_glossary id=\"482\"]bolide[\/pb_glossary] impacted. It was not until 1991 <\/span><span style=\"font-weight: 400\">that the crater was confirmed using [pb_glossary id=\"2415\"]petroleum[\/pb_glossary] company geophysical data. Even though it is the third largest confirmed crater on Earth at roughly 180 km wide, the <\/span><b>[pb_glossary id=\"483\"]Chicxulub Crater[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> was hard to find due to being partially underwater and partially obscured by the dense forest canopy of the Yucatan Peninsula<\/span><span style=\"font-weight: 400\">. Coring of the center of the impact called the peak ring contained [pb_glossary id=\"1014\"]granite[\/pb_glossary], indicating the impact was so powerful that it lifted [pb_glossary id=\"1023\"]basement[\/pb_glossary] [pb_glossary id=\"1756\"]sediment[\/pb_glossary] from the [pb_glossary id=\"1658\"]crust[\/pb_glossary] several miles toward the surface<\/span><span style=\"font-weight: 400\">. In 2010, an international team of scientists reviewed 20 years of research and blamed the impact for the [pb_glossary id=\"755\"]extinction[\/pb_glossary]<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3337\" align=\"alignright\" width=\"298\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/India_Geology_Zones.jpg\"><img class=\"wp-image-588 size-medium\" title=\"By CamArchGrad (From: en:Image:India Geology Zones.jpg) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AIndia_Geology_Zones.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/India_Geology_Zones-298x300.jpg\" alt=\"It covers more than 200,000 square miles\" width=\"298\" height=\"300\"><\/a> Geology of India, showing purple as Deccan Traps-related rocks.[\/caption]<span style=\"font-weight: 400\">With all of this information, it seems like the case would be closed. However, there are other events at this time which could have partially aided the demise of so many organisms. For example, sea levels are known to be slowly decreasing at the time of the K-T event, which is tied to [pb_glossary id=\"1961\"]marine[\/pb_glossary] extinctions<\/span><span style=\"font-weight: 400\">, though any study on gradual vs. sudden changes in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record is flawed due to the incomplete nature of the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record<\/span><span style=\"font-weight: 400\">. <\/span><span style=\"font-weight: 400\">Another big event at this time was the <\/span><b>Deccan [pb_glossary id=\"2420\"]Traps[\/pb_glossary]<\/b><span style=\"font-weight: 400\">\u00a0[pb_glossary id=\"244\"]flood basalt[\/pb_glossary] [pb_glossary id=\"228\"]volcanism[\/pb_glossary] in India. At over 1.3 million cubic kilometers of material, it was certainly a large source of material hazardous to ecosystems at the time, and it has been suggested as at least partially responsible for the [pb_glossary id=\"755\"]extinction[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Some have found the impact and eruptions too much of a coincidence, and have even linked the two together<\/span><span style=\"font-weight: 400\">.<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"54\"]\n\n[caption id=\"attachment_4247\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-589\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.7 via this QR Code.[\/caption]\n<h2><strong>8.8 Phanerozoic Eon: Cenozoic Era<\/strong><\/h2>\n[caption id=\"attachment_3338\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Paracertherium.png\"><img class=\"wp-image-590 size-medium\" title=\"By Tim Bertelink (Own work) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0&quot;>CC BY-SA 4.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AIndricotherium.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Paracertherium-300x234.png\" alt=\"It is grey and tall.\" width=\"300\" height=\"234\"><\/a> Paraceratherium, seen in this reconstruction, was a massive (15-20 ton, 15 foot tall) ancestor of rhinos.[\/caption]<span style=\"font-weight: 400\">The <strong>[pb_glossary id=\"488\"]Cenozoic[\/pb_glossary]<\/strong>, meaning \u201cnew life,\u201d is known as the age of mammals because it is in this [pb_glossary id=\"1243\"]era[\/pb_glossary] that mammals came to be a dominant and large life form, including human ancestors. Birds, as well, flourished in the open niches left by the dinosaur\u2019s demise. Most of the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] has been relatively warm, with the main exception being the [pb_glossary id=\"747\"]ice age[\/pb_glossary] that started about 2.558 million years ago and (despite recent warming) continues today<\/span><span style=\"font-weight: 400\">. [pb_glossary id=\"1654\"]Tectonic[\/pb_glossary] shifts in the west caused [pb_glossary id=\"228\"]volcanism[\/pb_glossary], but eventually changed the long-standing [pb_glossary id=\"1680\"]subduction[\/pb_glossary] zone into a [pb_glossary id=\"1679\"]transform[\/pb_glossary] boundary.<\/span>\n<h3><span style=\"font-weight: 400\">8.8.1 Cenozoic Tectonics and Paleogeography<\/span><\/h3>\n[caption id=\"attachment_4255\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Plate-Tectonics-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-4255\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Plate-Tectonics-Youtube-QR-Code-1.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access this YouTube video via this QR Code.[\/caption]\n\n[embed]https:\/\/www.youtube.com\/embed\/IDTBY5WDELg[\/embed]\n\n&nbsp;\n\n<em>Animation of the last 38 million years of movement in western North America. Note, that after the ridge is [pb_glossary id=\"1680\"]<em>subducted<\/em>[\/pb_glossary], [pb_glossary id=\"1678\"]<em>convergent<\/em>[\/pb_glossary] turns to [pb_glossary id=\"1679\"]<em>transform<\/em>[\/pb_glossary] (with [pb_glossary id=\"1677\"]<em>divergent<\/em>[\/pb_glossary] inland).<\/em>\n\n[caption id=\"attachment_3339\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Shallow_subduction_Laramide_orogeny.png\"><img class=\"wp-image-3339 size-medium\" title=\"By Melanie Moreno (Archived source link) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AShallow_subduction_Laramide_orogeny.png&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Shallow_subduction_Laramide_orogeny-1.png\" alt=\"The subducting plate goes right under the overriding plate\" width=\"300\" height=\"142\"><\/a> Shallow subduction during the Laramide Orogeny.[\/caption]<span style=\"font-weight: 400\">In the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary], the [pb_glossary id=\"1669\"]plates[\/pb_glossary] of the Earth moved into more familiar places, with the biggest change being the closing of the Tethys Sea with [pb_glossary id=\"1698\"]collisions[\/pb_glossary] such as the Alps, Zagros, and Himalaya, a [pb_glossary id=\"1698\"]collision[\/pb_glossary] that started about 57 million years ago, and continues today<\/span><span style=\"font-weight: 400\">. Maybe the most significant [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] feature that occurred in the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] of North America was the conversion of the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] of California from a [pb_glossary id=\"1678\"]convergent[\/pb_glossary] boundary [pb_glossary id=\"1680\"]subduction[\/pb_glossary] zone to a [pb_glossary id=\"1679\"]transform[\/pb_glossary] boundary. [pb_glossary id=\"1680\"]Subduction[\/pb_glossary] off the [pb_glossary id=\"1968\"]coast[\/pb_glossary] of the western United States, which had occurred throughout the [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary], had continued in the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary]. After the Sevier [pb_glossary id=\"1663\"]Orogeny[\/pb_glossary] in the late [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary], a subsequent [pb_glossary id=\"1663\"]orogeny[\/pb_glossary] called the Laramide [pb_glossary id=\"1663\"]Orogeny[\/pb_glossary], occurred in the early [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. The Laramide was [pb_glossary id=\"1690\"]thick-skinned[\/pb_glossary], different than the Sevier [pb_glossary id=\"1663\"]Orogeny[\/pb_glossary]. It involved deeper crustal rocks, and produced bulges that would become mountain ranges like the Rockies, Black Hills, Wind [pb_glossary id=\"2212\"]River[\/pb_glossary] Range, Uinta Mountains, and the San Rafael Swell. Instead of descending directly into the [pb_glossary id=\"1664\"]mantle[\/pb_glossary], the [pb_glossary id=\"1680\"]subducting[\/pb_glossary] [pb_glossary id=\"1669\"]plate[\/pb_glossary] shallowed out and moved eastward beneath the [pb_glossary id=\"1653\"]continental[\/pb_glossary] [pb_glossary id=\"1669\"]plate[\/pb_glossary] affecting the overlying [pb_glossary id=\"1653\"]continent[\/pb_glossary] hundreds of miles east of the [pb_glossary id=\"1653\"]continental[\/pb_glossary] margin and building high mountains.\u00a0 This occurred because the [pb_glossary id=\"1680\"]subducting[\/pb_glossary] [pb_glossary id=\"1669\"]plate[\/pb_glossary] was so young and near the [pb_glossary id=\"1708\"]spreading center[\/pb_glossary] and the density of the [pb_glossary id=\"1669\"]plate[\/pb_glossary] was therefore low and [pb_glossary id=\"1680\"]subduction[\/pb_glossary] was hindered.\u00a0<\/span>\n\n[caption id=\"attachment_3340\" align=\"alignright\" width=\"217\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sanandreas.jpg\"><img class=\"wp-image-3340 size-medium\" title=\"By Kate Barton, David Howell, and Joe Vigil [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASanandreas.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Sanandreas-1.jpg\" alt=\"The fault runs through California.\" width=\"217\" height=\"300\"><\/a> Map of the San Andreas fault, showing relative motion.[\/caption]<span style=\"font-weight: 400\">As the [pb_glossary id=\"1708\"]mid-ocean ridge[\/pb_glossary] itself started to subduct, the relative motion had changed. [pb_glossary id=\"1680\"]Subduction[\/pb_glossary] caused a relative convergence between the [pb_glossary id=\"1680\"]subducting[\/pb_glossary] Farallon [pb_glossary id=\"1669\"]plate[\/pb_glossary] and the North American [pb_glossary id=\"1669\"]plate[\/pb_glossary]. On the other side of the [pb_glossary id=\"1708\"]mid-ocean ridge[\/pb_glossary] from the Farallon [pb_glossary id=\"1669\"]plate[\/pb_glossary] was the Pacific [pb_glossary id=\"1669\"]plate[\/pb_glossary], which was moving away from the North American [pb_glossary id=\"1669\"]plate[\/pb_glossary]. Thus, as the [pb_glossary id=\"1680\"]subduction[\/pb_glossary] zone consumed the [pb_glossary id=\"1708\"]mid-ocean ridge[\/pb_glossary], the relative movement became [pb_glossary id=\"1679\"]transform[\/pb_glossary] instead of [pb_glossary id=\"1678\"]convergent[\/pb_glossary], which went on to become the San Andreas Fault System<\/span><span style=\"font-weight: 400\">. As the San Andreas grew, it caused east-west directed [pb_glossary id=\"492\"]extensional[\/pb_glossary] forces to spread over the western United States, creating the [pb_glossary id=\"1514\"]Basin and Range[\/pb_glossary] province<\/span><span style=\"font-weight: 400\">. The [pb_glossary id=\"1679\"]transform[\/pb_glossary] [pb_glossary id=\"2143\"]fault[\/pb_glossary] switched position over the last 18 million years, twisting the mountains around Los Angeles<\/span><span style=\"font-weight: 400\">, and new [pb_glossary id=\"2143\"]faults[\/pb_glossary] in the southeastern California deserts may become a future San Andreas-style [pb_glossary id=\"2143\"]fault[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. During this switch from [pb_glossary id=\"1680\"]subduction[\/pb_glossary] to [pb_glossary id=\"1679\"]transform[\/pb_glossary], the nearly horizontal Farallon [pb_glossary id=\"1683\"]slab[\/pb_glossary] began to sink into the [pb_glossary id=\"1664\"]mantle[\/pb_glossary]. This caused magmatism as the [pb_glossary id=\"1680\"]subducting[\/pb_glossary] [pb_glossary id=\"1683\"]slab[\/pb_glossary] sank, allowing [pb_glossary id=\"1671\"]asthenosphere[\/pb_glossary] material to rise around it. This event is called the Oligocene ignimbrite flare-up, which was one of the most significant [pb_glossary id=\"1244\"]periods[\/pb_glossary] of [pb_glossary id=\"228\"]volcanism[\/pb_glossary] ever<\/span><span style=\"font-weight: 400\">, including the largest single confirmed eruption, the 5000 cubic kilometer Fish Canyon [pb_glossary id=\"1005\"]Tuff[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. <\/span>\n<h3><span style=\"font-weight: 400\">8.8.2 Cenozoic Evolution<\/span><\/h3>\n[caption id=\"attachment_3341\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hominidae_chart.svg_.png\"><img class=\"wp-image-594 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-300x101.png\" alt=\"Humans are most replated to Pan (chimpanzee)\" width=\"300\" height=\"101\"><\/a> Family tree of Hominids (Hominadae).[\/caption]\n\n<span style=\"font-weight: 400\">There are five groups of early mammals in the [pb_glossary id=\"1228\"]fossil[\/pb_glossary] record, based primarily on [pb_glossary id=\"1228\"]fossil[\/pb_glossary] teeth, the hardest bone in [pb_glossary id=\"1274\"]vertebrate[\/pb_glossary] skeletons<\/span><span style=\"font-weight: 400\">. For the purpose of this text, the most important group are the Eupantotheres, that diverge into the two main groups of mammals, the marsupials (like <\/span><i><span style=\"font-weight: 400\">Sinodelphys<\/span><\/i><span style=\"font-weight: 400\">) and placentals or eutherians (like <\/span><i><span style=\"font-weight: 400\">Eomaia<\/span><\/i><span style=\"font-weight: 400\">) in the [pb_glossary id=\"487\"]Cretaceous[\/pb_glossary] and then diversified in the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary]. \u00a0The marsupials dominated on the isolated island continents of South America and Australia, and many went [pb_glossary id=\"755\"]extinct[\/pb_glossary] in South America with the introduction of placental mammals. Some well-known mammal groups have been highly studied with interesting evolutionary stories in the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary]. For example, horses started small with four toes, ended up larger and having just one toe<\/span><span style=\"font-weight: 400\">. Cetaceans ([pb_glossary id=\"1961\"]marine[\/pb_glossary] mammals like whales and dolphins) started on land from small bear-like (mesonychids) creatures in the early [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] and gradually took to water<\/span><span style=\"font-weight: 400\">. However, no study of evolution has been more studied than human evolution. <\/span><b>Hominids<\/b><span style=\"font-weight: 400\">, the name for human-like primates, started in eastern Africa several\u00a0million years ago.<\/span>\n\n[caption id=\"attachment_3342\" align=\"alignright\" width=\"199\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Lucy_Skeleton.jpg\"><img class=\"wp-image-595 size-medium\" title=\"By Andrew from Cleveland, Ohio, USA (Lucy) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.0&quot;>CC BY-SA 2.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ALucy_Skeleton.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lucy_Skeleton-199x300.jpg\" alt=\"The fossil is about 1\/2 complete\" width=\"199\" height=\"300\"><\/a> Lucy skeleton, showing real fossil (brown) and reconstructed skeleton (white).[\/caption]<span style=\"font-weight: 400\">The first critical event in this story is an environmental change from jungle to more of a savanna<\/span><span style=\"font-weight: 400\">, probably caused by changes in Indian Ocean circulation. While bipedalism is known to have evolved before this shift<\/span><span style=\"font-weight: 400\">, it is generally believed that our bipedal ancestors (like <\/span><i><span style=\"font-weight: 400\">Australopithecus<\/span><\/i><span style=\"font-weight: 400\">) had an advantage by covering ground more easily in a more open environment compared to their non-bipedal evolutionary cousins. There is also a growing body of evidence, including the famous \u201cLucy\u201d [pb_glossary id=\"1228\"]fossil[\/pb_glossary] of an Australopithecine, that our early ancestors lived in trees<\/span><span style=\"font-weight: 400\">. Arboreal animals usually demand a high intelligence to navigate through a three-dimensional world. It is from this lineage that humans evolved, using endurance running as a means to acquire more resources and possibly even hunt<\/span><span style=\"font-weight: 400\">. This can explain many uniquely human features, from our long legs, strong achilles, lack of lower gut protection, and our wide range of running efficiencies. <\/span>\n\n[caption id=\"attachment_3343\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Spreading_homo_sapiens.png\"><img class=\"wp-image-596 size-medium\" title=\"By NordNordWest (File:Spreading homo sapiens ru.svg by Urutseg) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASpreading_homo_sapiens_la.svg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Spreading_homo_sapiens-300x141.png\" alt=\"They started in Africa and migrated toward Asia and beyond.\" width=\"300\" height=\"141\"><\/a> The hypothesized movement of the homo genus. Years are marked as to the best guess of the timing of movement.[\/caption]<span style=\"font-weight: 400\">Now that the hands are freed up, the next big step is a large brain. There have been arguments from a switch to more meat eating<\/span><span style=\"font-weight: 400\">, cooking with fire<\/span><span style=\"font-weight: 400\">, tool use<\/span><span style=\"font-weight: 400\">, and even the construct of society itself<\/span><span style=\"font-weight: 400\"> to explain this increase in brain size. Regardless of how, it was this increased cognitive power that allowed humans to reign as their ancestors moved out of Africa and explored the world, ultimately entering the Americas through land bridges like the Bering Land Bridge<\/span><span style=\"font-weight: 400\">. The details of this worldwide migration and the different branches of the hominid evolutionary tree are very complex, and best reserved for its own\u00a0course.<\/span>\n<h4><span style=\"font-weight: 400\">Anthropocene and Extinction<\/span><\/h4>\n[caption id=\"attachment_3344\" align=\"alignright\" width=\"293\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/8.8_Extinctions_Africa_Austrailia_NAmerica_Madagascar.gif\"><img class=\"wp-image-597 size-medium\" title=\"By ElinWhitneySmith at English Wikipedia (Own work by the original uploader) [Public domain], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AExtinctions_Africa_Austrailia_NAmerica_Madagascar.gif&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8_Extinctions_Africa_Austrailia_NAmerica_Madagascar-293x300.gif\" alt=\"The mammals generally decrease after humans come.\" width=\"293\" height=\"300\"><\/a> Graph showing abundance of large mammals and the introduction of humans.[\/caption]<span style=\"font-weight: 400\">Humans have had an influence on the Earth, its ecosystems and [pb_glossary id=\"757\"]climate[\/pb_glossary]. Yet, human activity can not explain all of the changes that have occurred in the recent past. The start of the [pb_glossary id=\"491\"]Quaternary[\/pb_glossary] [pb_glossary id=\"1244\"]period[\/pb_glossary], the last and current [pb_glossary id=\"1244\"]period[\/pb_glossary] of the [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary], is marked by the start of our current [pb_glossary id=\"747\"]ice age[\/pb_glossary] 2.58 million years ago<\/span><span style=\"font-weight: 400\">. During this time [pb_glossary id=\"1244\"]period[\/pb_glossary], [pb_glossary id=\"1519\"]ice sheets[\/pb_glossary] advanced and retreated, most likely due to [pb_glossary id=\"748\"]Milankovitch cycles[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/15-global-climate-change\/\">ch. 15<\/a>). Also at this time, various cold-adapted megafauna emerged (like giant sloths, saber-tooth cats, and woolly mammoths), and most of them went [pb_glossary id=\"755\"]extinct[\/pb_glossary] as the Earth warmed from the most recent [pb_glossary id=\"1988\"]glacial[\/pb_glossary] maximum. A long-standing debate is over the cause of these and other extinctions. Is [pb_glossary id=\"757\"]climate[\/pb_glossary] warming to blame, or were they caused by humans<\/span><span style=\"font-weight: 400\">? Certainly, we know of recent human extinctions of animals like the dodo or passenger pigeon. Can we connect modern extinctions to extinctions in the recent past? If so, there are several ideas as to how this happened. Possibly the most widely accepted and oldest is the hunting\/overkill [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. The idea behind this [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] is that humans hunted large herbivores for food, then carnivores could not find food, and human arrival times in locations has been shown to be tied to increased [pb_glossary id=\"755\"]extinction[\/pb_glossary] rates in many cases.<\/span>\n\n[caption id=\"attachment_3345\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bingham_Canyon_mine_2016.jpg\"><img class=\"wp-image-598 size-medium\" title=\"By Doc Searls from Santa Barbara, USA (2016_02_16_lga-ord-slc_156) [<a href=&quot;http:\/\/creativecommons.org\/licenses\/by\/2.0&quot;>CC BY 2.0<\/a>], <a href=&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABingham_Canyon_mine_2016.jpg&quot;>via Wikimedia Commons<\/a>\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bingham_Canyon_mine_2016-300x180.jpg\" alt=\"The image is a large hole in a mountainside.\" width=\"300\" height=\"180\"><\/a> Bingham Canyon Mine, Utah. This open pit mine is the largest man-made removal of rock in the world.[\/caption]<span style=\"font-weight: 400\">Modern human impact on the environment and the Earth as a whole is unquestioned. In fact, many scientists are starting to suggest that the rise of human civilization ended and\/or replaced the [pb_glossary id=\"490\"]Holocene[\/pb_glossary] [pb_glossary id=\"1245\"]epoch[\/pb_glossary] and defines a new geologic time interval: the <\/span><b>[pb_glossary id=\"489\"]Anthropocene[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. Evidence for this change includes extinctions, increased tritium (hydrogen with two neutrons) due to nuclear testing, rising pollutants like carbon dioxide, more than 200 never-before seen [pb_glossary id=\"1765\"]mineral[\/pb_glossary] species that have occurred only in this [pb_glossary id=\"1245\"]epoch[\/pb_glossary]<\/span><span style=\"font-weight: 400\">, materials such as plastic and metals which will be\u00a0long lasting \"[pb_glossary id=\"1228\"]fossils[\/pb_glossary]\" in the geologic record, and large amounts of earthen material moved<\/span><span style=\"font-weight: 400\">. The biggest scientific debate with this topic is the starting point. Some say that humans\u2019 invention of agriculture would be recognized in geologic [pb_glossary id=\"1935\"]strata[\/pb_glossary] and that should be the starting point, around 12,000 years ago<\/span><span style=\"font-weight: 400\">. Others link the start of the industrial revolution and the subsequent addition of vast amounts of carbon dioxide in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]<\/span><span style=\"font-weight: 400\">. Either way, the idea is that alien geologists visiting Earth in the distant future would easily recognize the impact of humans on the Earth as the beginning of a new geologic [pb_glossary id=\"1244\"]period[\/pb_glossary].<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"55\"]\n\n[caption id=\"attachment_4249\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.8-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-599\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 8.8 via this QR Code.[\/caption]\n<h2>Summary<\/h2>\nThe changes that have occurred since the inception of Earth are vast and significant. From the oxygenation of the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary], the progression of life forms, the assembly and deconstruction of several [pb_glossary id=\"1701\"]supercontinents[\/pb_glossary], to the [pb_glossary id=\"755\"]extinction[\/pb_glossary] of more life forms than exist today, having a general understanding of these changes can put present change into a more rounded perspective.\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n[h5p id=\"56\"]\n\n[caption id=\"attachment_4250\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Ch.8-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-600\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the review quiz for Chapter 8 via this QR Code.[\/caption]\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n \t<li class=\"csl-entry\">Alvarez, L.W., Alvarez, W., Asaro, F., and Michel, H.V., 1980, Extraterrestrial cause for the [pb_glossary id=\"487\"]cretaceous[\/pb_glossary]-tertiary [pb_glossary id=\"755\"]extinction[\/pb_glossary]: Science, v. 208, no. 4448, p. 1095\u20131108.<\/li>\n \t<li class=\"csl-entry\">Beerling, D., 2008, The emerald planet: how plants changed Earth\u2019s history: OUP Oxford.<\/li>\n \t<li class=\"csl-entry\">Boyce, J.W., Liu, Y., Rossman, G.R., Guan, Y., Eiler, J.M., Stolper, E.M., and Taylor, L.A., 2010, Lunar apatite with [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] volatile abundances: Nature, v. 466, no. 7305, p. 466\u2013469.<\/li>\n \t<li class=\"csl-entry\">Brueckner, H.K., and Snyder, W.S., 1985, Structure of the Havallah sequence, Golconda allochthon, Nevada: Evidence for prolonged evolution in an accretionary prism: Geol. Soc. Am. Bull., v. 96, no. 9, p. 1113\u20131130.<\/li>\n \t<li class=\"csl-entry\">Brusatte, S.L., Benton, M.J., Ruta, M., and Lloyd, G.T., 2008, The first 50 Myr of dinosaur evolution: macroevolutionary pattern and morphological disparity: Biol. Lett., v. 4, no. 6, p. 733\u2013736.<\/li>\n \t<li class=\"csl-entry\">Canup, R.M., and Asphaug, E., 2001, Origin of the Moon in a giant impact near the end of the Earth\u2019s [pb_glossary id=\"2038\"]formation[\/pb_glossary]: Nature, v. 412, no. 6848, p. 708\u2013712.<\/li>\n \t<li class=\"csl-entry\">Clack, J.A., 2009, The Fish\u2013Tetrapod Transition: New [pb_glossary id=\"1228\"]Fossils[\/pb_glossary] and Interpretations: Evolution: Education and Outreach, v. 2, no. 2, p. 213\u2013223., doi: <a href=\"https:\/\/doi.org\/10\/cz257q\">10\/cz257q<\/a>.<\/li>\n \t<li class=\"csl-entry\">Cohen, K.M., Finney, S.C., Gibbard, P.L., and Fan, J.-X., 2013, The ICS International Chronostratigraphic Chart: Episodes, v. 36, no. 3, p. 199\u2013204.<\/li>\n \t<li class=\"csl-entry\">Colbert, E.H., and Morales, M.A., 1991, History of the Backboned Animals Through Time: New York: Wiley.<\/li>\n \t<li class=\"csl-entry\">De Laubenfels, M.W., 1956, Dinosaur [pb_glossary id=\"755\"]extinction[\/pb_glossary]: one more [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary]: J. Paleontol.<\/li>\n \t<li class=\"csl-entry\">Gomes, R., Levison, H.F., Tsiganis, K., and Morbidelli, A., 2005, Origin of the cataclysmic [pb_glossary id=\"1258\"]Late Heavy Bombardment[\/pb_glossary] period of the [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] planets: Nature, v. 435, no. 7041, p. 466\u2013469.<\/li>\n \t<li class=\"csl-entry\">Hatcher, R.D., Jr, Thomas, W.A., and Viele, G.W., 1989, The Appalachian-Ouachita Orogen in the United States: Geological Society of America.<\/li>\n \t<li class=\"csl-entry\">Hosono, N., Karato, S., Makino, J., and Saitoh, T.R., 2019, [pb_glossary id=\"1980\"]Terrestrial[\/pb_glossary] [pb_glossary id=\"1750\"]magma[\/pb_glossary] ocean origin of the Moon: Nature Geoscience, p. 1., doi: <a href=\"https:\/\/doi.org\/10.1038\/s41561-019-0354-2\">10.1038\/s41561-019-0354-2<\/a>.<\/li>\n \t<li class=\"csl-entry\">Hsiao, E., 2004, Possibility of life on Europa:<\/li>\n \t<li class=\"csl-entry\">Hubble, E., 1929, A relation between distance and radial velocity among extra-galactic nebulae: Proc. Natl. Acad. Sci. U. S. A., v. 15, no. 3, p. 168\u2013173.<\/li>\n \t<li class=\"csl-entry\">Ingersoll, R.V., 1982, Triple-junction instability as cause for late [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] [pb_glossary id=\"492\"]extension[\/pb_glossary] and fragmentation of the western United States: Geology, v. 10, no. 12, p. 621\u2013624.<\/li>\n \t<li class=\"csl-entry\">Johnson, C.M., 1991, Large-scale [pb_glossary id=\"1658\"]crust[\/pb_glossary] [pb_glossary id=\"2038\"]formation[\/pb_glossary] and [pb_glossary id=\"1668\"]lithosphere[\/pb_glossary] modification beneath Middle to Late [pb_glossary id=\"488\"]Cenozoic[\/pb_glossary] calderas and [pb_glossary id=\"228\"]volcanic[\/pb_glossary] fields, western North America: J. Geophys. Res. [Solid Earth], v. 96, no. B8, p. 13485\u201313507.<\/li>\n \t<li class=\"csl-entry\">Kass, M.S., 1999, Prognathodon stadtmani:(Mosasauridae) a new species from the Mancos [pb_glossary id=\"1917\"]Shale[\/pb_glossary] (lower Campanian) of western Colorado: [pb_glossary id=\"2595\"]Vertebrate[\/pb_glossary] Paleontology in Utah, Utah Geological.<\/li>\n \t<li class=\"csl-entry\">Livaccari, R.F., 1991, Role of crustal thickening and [pb_glossary id=\"492\"]extensional[\/pb_glossary] collapse in the [pb_glossary id=\"1654\"]tectonic[\/pb_glossary]\u00a0evolution of the Sevier-Laramide [pb_glossary id=\"1663\"]orogeny[\/pb_glossary], western United States: Geology, v. 19, no. 11, p. 1104\u20131107.<\/li>\n \t<li class=\"csl-entry\">McMenamin, M.A., and Schulte McMenamin, D.L., 1990, The Emergence of Animals: The [pb_glossary id=\"1276\"]Cambrian[\/pb_glossary] Breakthrough: Columbia University Press.<\/li>\n \t<li class=\"csl-entry\">Mitrovica, J.X., Beaumont, C., and Jarvis, G.T., 1989, Tilting of [pb_glossary id=\"1653\"]continental[\/pb_glossary] interiors by the dynamical effects of [pb_glossary id=\"1680\"]subduction[\/pb_glossary]: [pb_glossary id=\"1654\"]Tectonics[\/pb_glossary].<\/li>\n \t<li class=\"csl-entry\">R\u00fccklin, M., Donoghue, P.C.J., Johanson, Z., Trinajstic, K., Marone, F., and Stampanoni, M., 2012, Development of teeth and jaws in the earliest jawed [pb_glossary id=\"1274\"]vertebrates[\/pb_glossary]: Nature, v. 491, no. 7426, p. 748\u2013751.<\/li>\n \t<li class=\"csl-entry\">Sahney, S., and Benton, M.J., 2008, Recovery from the most profound [pb_glossary id=\"1275\"]mass extinction[\/pb_glossary] of all time: Proc. Biol. Sci., v. 275, no. 1636, p. 759\u2013765.<\/li>\n \t<li class=\"csl-entry\">Salaris, M., and Cassisi, S., 2005, Evolution of stars and stellar populations: John Wiley &amp; Sons.<\/li>\n \t<li class=\"csl-entry\">Schoch, R.R., 2012, Amphibian Evolution: The life of Early Land [pb_glossary id=\"1274\"]Vertebrates[\/pb_glossary]: Wiley-Blackwell.<\/li>\n \t<li class=\"csl-entry\">Sharp, B.J., 1958, MINERALIZATION IN THE [pb_glossary id=\"991\"]INTRUSIVE[\/pb_glossary] ROCKS IN LITTLE COTTONWOOD CANYON, UTAH: GSA Bulletin, v. 69, no. 11, p. 1415\u20131430., doi: <a href=\"https:\/\/doi.org\/10.1130\/0016-7606(1958)69[1415:MITIRI]2.0.CO;2\">10.1130\/0016-7606(1958)69[1415:MITIRI]2.0.CO;2<\/a>.<\/li>\n \t<li class=\"csl-entry\">Wiechert, U., Halliday, A.N., Lee, D.C., Snyder, G.A., Taylor, L.A., and Rumble, D., 2001, Oxygen [pb_glossary id=\"1779\"]isotopes[\/pb_glossary] and the moon-forming giant impact: Science, v. 294, no. 5541, p. 345\u2013348.<\/li>\n \t<li class=\"csl-entry\">Wilde, S.A., Valley, J.W., Peck, W.H., and Graham, C.M., 2001, Evidence from [pb_glossary id=\"2441\"]detrital[\/pb_glossary] [pb_glossary id=\"1227\"]zircons[\/pb_glossary] for the existence of [pb_glossary id=\"1653\"]continental crust[\/pb_glossary] and oceans on the Earth 4.4 Gyr ago: Nature, v. 409, no. 6817, p. 175\u2013178.<\/li>\n \t<li class=\"csl-entry\">Wood, R.A., 2019, The rise of Animals.: Scientific American, v. 320, no. 6, p. 24\u201331.<\/li>\n<\/ol>\n<\/div>","rendered":"<figure id=\"attachment_3273\" aria-describedby=\"caption-attachment-3273\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CdC1-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3273 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/CdC1-scaled-1.jpg\" alt=\"The rock is a 750' spire.\" width=\"1024\" height=\"683\" \/><\/a><figcaption id=\"caption-attachment-3273\" class=\"wp-caption-text\">Spider Rock, within Canyon de Chelly National Monument, not only has a long human history with the Din\u00e9 tribe, but also has a long geologic history. The rocks are Permian in age, and formed in the desert conditions that dominated North America toward the end of the Paleozoic through the middle Mesozoic. Erosion of the canyon occurred in the Cenozoic.<\/figcaption><\/figure>\n<p><strong>KEY CONCEPTS<\/strong><\/p>\n<p><strong>By the end of this chapter, students should be able to:<\/strong><\/p>\n<ul>\n<li>Explain the big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a> and origin of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a><\/li>\n<li>Explain the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>\u2019s origin and the consequences for Earth.<\/li>\n<li>Describe the turbulent beginning of Earth during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eons<\/a><\/li>\n<li>Identify the transition to modern <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a>, and evolution that occurred in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a><\/li>\n<li>Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> evolution and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> of invertebrates with hard parts, fish, amphibians, reptiles, tetrapods, and land plants; and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonics<\/a> and sedimentation associated with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinent<\/a> Pangea<\/li>\n<li>Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> evolution and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> of birds, dinosaurs, and mammmals; and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonics<\/a> and sedimentation associated with the breakup of Pangea<\/li>\n<li>Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> evolution of mammals and birds, paleoclimate, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonics<\/a> that shaped the modern world<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2486\" aria-describedby=\"caption-attachment-2486\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/GeologicClock.png\"><img decoding=\"async\" class=\"wp-image-52 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-2486\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/GeologicClock-300&#215;288.png\u00a0\u00bb alt=\u00a0\u00bbThe circle starts at 4.6 billion years ago, then loops around to zero.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb288&Prime;&gt; Geologic time on Earth, represented circularly, to show the individual time divisions and important events. Ga=billion years ago, Ma=million years ago.<\/figcaption><\/figure>\n<p>Entire courses and careers have been based on the wide-ranging topics covering Earth\u2019s history. Throughout the long history of Earth, change has been the norm. Looking back in time, an untrained eye would see many unfamiliar life forms and terrains. The main topics studied in Earth history are paleogeography, paleontology, and paleoecology and paleoclimatology\u2014respectively, past landscapes, past organisms, past ecosystems, and past environments. This chapter will cover briefly the origin of the universe and the 4.6 billion year history of Earth. This Earth history will <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2158\">focus<\/a> on the major physical and biological events in each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eons<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>.<\/p>\n<h2><strong>8.1 Origin of the Universe<\/strong><\/h2>\n<figure id=\"attachment_3275\" aria-describedby=\"caption-attachment-3275\" style=\"width: 349px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/HubbleDeepField.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-519\" title=\"NASA, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-300x294.jpg\" alt=\"The picture has over 1500 galaxies.\" width=\"349\" height=\"342\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-300x294.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-1024x1003.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-768x752.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-1536x1505.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-65x64.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-225x220.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField-350x343.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HubbleDeepField.jpg 1568w\" sizes=\"auto, (max-width: 349px) 100vw, 349px\" \/><\/a><figcaption id=\"caption-attachment-3275\" class=\"wp-caption-text\">The Hubble Deep Field. This image, released in 1996, is a composite long-exposure picture of one of the darkest parts of the night sky. Every light on this image that does not have diffraction spikes is believed to be an entire galaxy, with hundreds of billions of stars, demonstrating the immense size and scope of the universe.<\/figcaption><\/figure>\n<p>The universe appears to have an infinite number of galaxies and solar systems and our <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> occupies a small section of this vast entirety. The origins of the universe and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> set the context for conceptualizing the Earth\u2019s origin and early history.<\/p>\n<h3><b>8.1.1 Big-Bang Theory<\/b><\/h3>\n<figure id=\"attachment_3276\" aria-describedby=\"caption-attachment-3276\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/UniverseTimeline.jpg\"><img decoding=\"async\" class=\"wp-image-520 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3276\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/UniverseTimeline-300&#215;195.jpg\u00a0\u00bb alt=\u00a0\u00bbIt starts small, then explodes outward\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb195&Prime;&gt; Timeline of expansion of the Universe<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The mysterious details of events prior to and during the origin of the universe are subject to great scientific debate. The prevailing idea about how the universe was created is called the <strong>big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a><\/strong>. Although the ideas behind the big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a> feel almost mystical, they are supported by Einstein\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a> of general relativity. Other scientific evidence, grounded in empirical observations, supports the big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a>.<\/span><\/p>\n<p><span style=\"font-weight: 400\">The big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a> proposes the universe was formed from an infinitely dense and hot <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a> of material. The bang in the title suggests there was an explosive, outward expansion of all matter and space that created atoms. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1719\">Spectroscopy<\/a> confirms that hydrogen makes up about 74% of all matter in the universe. Since its creation, the universe has been expanding for 13.8 billion years and recent observations suggest the rate of this expansion is increasing<\/span><span style=\"font-weight: 400\">.\u00a0<\/span><\/p>\n<h4><span style=\"font-weight: 400\">Spectroscopy<\/span><\/h4>\n<figure id=\"attachment_3277\" aria-describedby=\"caption-attachment-3277\" style=\"width: 383px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/EM_Spectrum_Properties_edit.svg_.png\"><img decoding=\"async\" class=\"wp-image-521\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3277\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEM_Spectrum_Properties_edit.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/EM_Spectrum_Properties_edit.svg_-300&#215;178.png\u00a0\u00bb alt=\u00a0\u00bbThe figure shows the various wavelengths of electromagnetic light, the scale of the wavelength, the frequency, and the temperature of objects that produces waves.\u00a0\u00bb width=\u00a0\u00bb383&Prime; height=\u00a0\u00bb227&Prime;&gt; The electromagnetic spectrum and properties of light across the spectrum.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1719\">Spectroscopy<\/a><\/strong> is the investigation and measurement of spectra produced when materials interacts with or emits electromagnetic radiation. <em>Spectra<\/em> is the plural for <em>spectrum<\/em> which is a particular wavelength from the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1720\">electromagnetic spectrum<\/a><\/strong>. Common spectra include the different colors of visible light, X-rays, ultraviolet waves, microwaves, and radio waves. Each beam of light is a unique mixture of wavelengths that combine across the spectrum to make the color we see. The light wavelengths are created or absorbed inside atoms, and each wavelength signature matches a specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>. Even white light from the Sun, which seems like an uninterrupted continuum of wavelengths, has gaps in some wavelengths. The gaps correspond to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> present in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> that act as filters for specific wavelengths. These missing wavelengths were famously observed by Joseph von Fraunhofer (1787\u20131826) in the early 1800s<\/span><span style=\"font-weight: 400\">, but it took decades before scientists were able to relate the missing wavelengths to atmospheric filtering<\/span><span style=\"font-weight: 400\">. <\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1719\">Spectroscopy<\/a> shows that the Sun is mostly made of hydrogen and helium. Applying this process to light from distant stars, scientists can calculate the abundance of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in a specific star and visible universe as a whole. Also, this spectroscopic information can be used as an interstellar speedometer.<\/p>\n<h4><span style=\"font-weight: 400\">Redshift<\/span><\/h4>\n<figure id=\"attachment_3278\" aria-describedby=\"caption-attachment-3278\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dopplerfrequenz.gif\"><img decoding=\"async\" class=\"wp-image-522 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3278\" class=\"wp-caption-text\">GFDL<\/a>, <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.5-2.0-1.0&quot;\">CC BY-SA 2.5-2.0-1.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADopplerfrequenz.gif&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dopplerfrequenz-300&#215;75.gif\u00a0\u00bb alt=\u00a0\u00bbIn this animated image, the car moves, and the waves are pushed in the front, and stretched behind it.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb75&Prime;&gt; The Doppler effect is heard as a car moves. The waves in front of the car are compressed together, making the pitch higher. The waves in the back of the car are stretched, and and the pitch gets lower.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1721\">Doppler effect<\/a><\/strong> is the same process that changes the pitch of the sound of an approaching car or ambulance from high to low as it passes. When an object emits waves, such as light or sound, while moving toward an observer, the wavelengths get compressed. In sound, this results in a shift to a higher pitch. When an object moves away from an observer, the wavelengths are extended, producing a lower pitched sound. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1721\">Doppler effect<\/a> is used on light emitted from stars and galaxies to determine their speed and direction of travel<\/span><span style=\"font-weight: 400\">. Scientists, including Vesto Slipher (1875\u20131969)<\/span><span style=\"font-weight: 400\"> and Edwin Hubble (1889\u20131953)<\/span><span style=\"font-weight: 400\">, examined galaxies both near and far and found that almost all galaxies outside of our galaxy are moving away from each other, and us. Because the light wavelengths of receding objects are extended, visible light is shifted toward the red end of the spectrum, called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1247\">redshift<\/a><\/strong>. In addition, Hubble noticed that galaxies that were farther away from Earth also had the greater amount of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1247\">redshift<\/a>, and thus, the faster they are traveling away from us. The only way to reconcile this information is to deduce the universe is still expanding. Hubble\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1729\">observation<\/a> forms the basis of big-bang <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a>.<\/span><\/p>\n<figure id=\"attachment_4252\" aria-describedby=\"caption-attachment-4252\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Example-of-Doppler-Shift-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-523\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Example-of-Doppler-Shift-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4252\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Example of Doppler Shift using car horn\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/a3RfULw7aAY?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<h4><span style=\"font-weight: 400\">Cosmic Microwave Background Radiation<\/span><\/h4>\n<figure id=\"attachment_3279\" aria-describedby=\"caption-attachment-3279\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CosmicBackground.png\"><img decoding=\"async\" class=\"wp-image-524 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3279\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CosmicBackground-300&#215;150.png\u00a0\u00bb alt=\u00a0\u00bbThe map is blue with slight bright spots of green\/yellow\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb150&Prime;&gt; Heat map, showing slight variations in background heat, which is related to cosmic background radiation.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Another strong indication of the big-bang is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1248\">cosmic microwave background radiation<\/a><\/strong>. Cosmic radiation was accidentally discovered by Arno Penzias (1933\u2013) and Robert Woodrow Wilson (1936\u2013) <\/span>when they were trying to eliminate background noise from a communication satellite. They discovered very faint traces of energy or heat that are omnipresent across the universe. This energy was left behind from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1246\">big bang<\/a>, like an echo.<\/p>\n<h3><b>8.1.2 Stellar Evolution<\/b><\/h3>\n<figure id=\"attachment_3280\" aria-describedby=\"caption-attachment-3280\" style=\"width: 400px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Nucleosynthesis_periodic_table.svg_-1.png\"><img decoding=\"async\" class=\"wp-image-525\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3280\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a> or <a href=\"denied:&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ANucleosynthesis_periodic_table.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Nucleosynthesis_periodic_table.svg_-1-300&#215;150.png\u00a0\u00bb alt=\u00a0\u00bbThis shows the period table. Some elements are made in the big bang, some are made in stellar processes.\u00a0\u00bb width=\u00a0\u00bb400&Prime; height=\u00a0\u00bb200&Prime;&gt; Origin of the elements on the periodic table, showing the important role the star life cycle plays.<\/figcaption><\/figure>\n<p>Astronomers think the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1246\">big bang<\/a> created lighter <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>, mostly hydrogen and smaller amounts of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> helium, lithium, and beryllium. Another process must be responsible for creating the other 90 heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. The current model of stellar evolution explains the origins of these heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>.<\/p>\n<h4><span style=\"font-weight: 400\">Birth of a star<\/span><\/h4>\n<figure id=\"attachment_3281\" aria-describedby=\"caption-attachment-3281\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Eagle_nebula_pillars.jpg\"><img decoding=\"async\" class=\"wp-image-526 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3281\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Eagle_nebula_pillars-300&#215;296.jpg\u00a0\u00bb alt=\u00a0\u00bbIt is several large column of gas\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb296&Prime;&gt; Section of the Eagle Nebula known as \u00ab\u00a0The Pillars of Creation.\u00a0\u00bb<\/figcaption><\/figure>\n<p>Stars start their lives as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> floating in cold, spinning clouds of gas and dust known as <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebulas<\/a><\/strong>. Gravitational attraction or perhaps a nearby stellar explosion causes the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> to condense and spin into disk shape. In the center of this disk shape a new star is born under the force of gravity. The spinning whirlpool concentrates material in the center, and the increasing gravitational forces collect even more mass. Eventually, the immensely concentrated mass of material reaches a critical point of such intense heat and pressure it initiates <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a>.<\/p>\n<h4><span style=\"font-weight: 400\">Fusion<\/span><\/h4>\n<figure id=\"attachment_3282\" aria-describedby=\"caption-attachment-3282\" style=\"width: 211px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/FusionintheSun.svg_.png\"><img decoding=\"async\" class=\"wp-image-527 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3282\" class=\"wp-caption-text\">Borb<\/a> [<a href=\"denied:&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFusionintheSun.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FusionintheSun.svg_-211&#215;300.png\u00a0\u00bb alt=\u00a0\u00bbThere are 3 steps\u00a0\u00bb width=\u00a0\u00bb211&Prime; height=\u00a0\u00bb300&Prime;&gt; General diagram showing the series of fusion steps that occur in the sun.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">Fusion<\/a> is not a chemical reaction. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">Fusion<\/a><\/strong> is a nuclear reaction in which two or more nuclei, the centers of atoms, are forced together and combine creating a new larger atom. This reaction gives off a tremendous amount of energy, usually as light and solar radiation. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> such as hydrogen combines or fuses with other hydrogen atoms in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a> of a star to become a new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>, in this case, helium. Another product of this process is energy, such as solar radiation that leaves the Sun and comes to the Earth as light and heat. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">Fusion<\/a> is a steady and predictable process, which is why we call this the main phase of a star\u2019s life. During its main phase, a star turns hydrogen into helium. Since most stars contain plentiful amounts of hydrogen, the main phase may last billions of years, during which their size and energy output remains relatively steady.<\/p>\n<figure id=\"attachment_3283\" aria-describedby=\"caption-attachment-3283\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Star_life_cycles_red_dwarf_en.svg_.png\"><img decoding=\"async\" class=\"wp-image-528 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3283\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStar_life_cycles_red_dwarf_en.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Star_life_cycles_red_dwarf_en.svg_-300&#215;200.png\u00a0\u00bb alt=\u00a0\u00bbIt shows many steps\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb200&Prime;&gt; Two main paths of a star&rsquo;s life cycle, depending on mass.<\/figcaption><\/figure>\n<p>The giant phase in a star\u2019s life occurs when the star runs out of hydrogen for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a>. If a star is large enough, it has sufficient heat and pressure to start fusing helium into heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. This style of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> is more energetic and the higher energy and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> expand the star to a larger size and brightness. This giant phase is predicted to happen to our Sun in another few billion years, growing the radius of the Sun to Earth\u2019s orbit, which will render life impossible. The mass of a star during its main phase is the primary factor in determining how it will evolve. If the star has enough mass and reaches a point at which the primary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>, such as helium, is exhausted, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> continues using new, heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. This occurs over and over in very large stars, forming progressively heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> like carbon and oxygen. Eventually, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> reaches its limit as it forms iron and nickel. This progression explains the abundance of iron and nickel in rocky objects, like Earth, within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>. At this point, any further <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> absorbs energy instead of giving it off, which is the beginning of the end of the star\u2019s life<span style=\"font-weight: 400\">.<\/span><\/p>\n<h4><span style=\"font-weight: 400\">Death of a Star<\/span><\/h4>\n<figure id=\"attachment_3284\" aria-describedby=\"caption-attachment-3284\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Crab_Nebula.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-529 size-medium\" title=\"NASA and ESA image, public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-300x300.jpg\" alt=\"The picture is of dust and gas.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-1024x1024.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-768x768.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Crab_Nebula.jpg 1200w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3284\" class=\"wp-caption-text\">Hubble space telescope image of the Crab Nebula, the remnants of a supernova that occurred in 1054 C.E.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The death of a star can range from spectacular to other-worldly (see figure). Stars like the Sun form a planetary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a>, which comes from the collapse of the star\u2019s outer layers in an event like the implosion of a building. In the tug-of-war between gravity\u2019s inward pull and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion\u2019s<\/a> outward push, gravity instantly takes over when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> ends, with the outer gasses puffing away to form a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a>. More <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> stars do this as well but with a more energetic collapse, which starts another type of energy release mixed with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> creation known as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1251\">supernova<\/a>. In a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1251\">supernova<\/a><\/strong>, the collapse of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a> suddenly halts, creating a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> outward-propagating shock wave. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1251\">supernova<\/a> is the most energetic explosion in the universe short of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1246\">big bang<\/a>. The energy release is so significant the ensuing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a> can make every <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> up through uranium<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3285\" aria-describedby=\"caption-attachment-3285\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/08.1_blackhole_NASA_2019.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-530 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-300x175.png\" alt=\"Blurry telescope photo of a fuzzy red halo around an entirely black center. The black center represents the first photograph of an actual black hole captured in 2019.\" width=\"300\" height=\"175\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-300x175.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-768x447.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-65x38.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-225x131.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019-350x204.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/08.1_blackhole_NASA_2019.png 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3285\" class=\"wp-caption-text\">A black hole and its shadow have been captured in an image for the first time in 2019, a historic feat by an international network of radio telescopes called the Event Horizon Telescope (Source: NASA)<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The death of the star can result in the creation of white dwarfs, neutron stars, or black holes. Following their deaths, stars like the Sun turn into white dwarfs<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<p>White dwarfs are hot star embers, formed by packing most of a dying star\u2019s mass into a small and dense object about the size of Earth. Larger stars may explode in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1251\">supernova<\/a> that packs their mass even tighter to become neutron stars. Neutron stars are so dense that protons combine with electrons to form neutrons. The largest stars collapse their mass even further, becoming objects so dense that light cannot escape their gravitational grasp. These are the infamous black holes and the details of the physics of what occurs in them are still up for debate.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-48\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-48\" class=\"h5p-iframe\" data-content-id=\"48\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4240\" aria-describedby=\"caption-attachment-4240\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.1-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-531\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.1-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4240\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.1 via this QR Code.<\/figcaption><\/figure>\n<h2><strong>8.2 Origin of the Solar System: The Nebular Hypothesis<\/strong><\/h2>\n<figure id=\"attachment_3286\" aria-describedby=\"caption-attachment-3286\" style=\"width: 252px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/M42proplyds.jpg\"><img decoding=\"async\" class=\"wp-image-532\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3286\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/M42proplyds-300&#215;224.jpg\u00a0\u00bb alt=\u00a0\u00bbIt is a small cloud\u00a0\u00bb width=\u00a0\u00bb252&Prime; height=\u00a0\u00bb188&Prime;&gt; Small protoplanetary discs in the Orion Nebula<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Our <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> formed at the same time as our Sun as described in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1252\">nebular hypothesis<\/a>. The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1252\">nebular hypothesis<\/a><\/strong> is the idea that a spinning cloud of dust made of mostly light <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>, called a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a>, flattened into a protoplanetary disk, and became a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> consisting of a star with orbiting planets<\/span><span style=\"font-weight: 400\">. <\/span>The spinning <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a> collected the vast majority of material in its center, which is why the sun Accounts for over 99% of the mass in our <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>.<\/p>\n<p>&nbsp;<\/p>\n<h3><b>8.2.1 Planet Arrangement and Segregation<\/b><\/h3>\n<figure id=\"attachment_3287\" aria-describedby=\"caption-attachment-3287\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fomalhaut_Circumstellar_Disk.jpg\"><img decoding=\"async\" class=\"wp-image-533 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3287\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fomalhaut_Circumstellar_Disk-300&#215;240.jpg\u00a0\u00bb alt=\u00a0\u00bbThe disc is lop sided\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb240&Prime;&gt; This disk is asymmetric, possibly because of a large gas giant planet orbiting relatively far from the star.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">As our <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> formed, the nebular cloud of dispersed particles developed distinct <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> zones. Temperatures were very high close to the center, only allowing condensation of metals and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> with high melting points. Farther from the Sun, the temperatures were lower, allowing the condensation of lighter gaseous molecules such as methane, ammonia, carbon dioxide, and water<\/span><span style=\"font-weight: 400\">. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> differentiation resulted in the inner four planets of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> becoming rocky, and the outer four planets becoming gas giants.<\/span><\/p>\n<figure id=\"attachment_3288\" aria-describedby=\"caption-attachment-3288\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/HL_Tau_protoplanetary_disk.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-534 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-300x300.jpg\" alt=\"The orange disk has zones that are darker, indicating the planets are growing by using that material in the disk.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/HL_Tau_protoplanetary_disk.jpg 480w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3288\" class=\"wp-caption-text\">Image by the ALMA telescope of HL Tauri and its protoplanetary disk, showing grooves formed as planets absorb material in the disk.<\/figcaption><\/figure>\n<p>Both rocky and gaseous planets have a similar growth model. Particles of dust, floating in the disc were attracted to each other by static charges and eventually, gravity. As the clumps of dust became bigger, they interacted with each other\u2014colliding, sticking, and forming proto-planets. The planets continued to grow over the course of many thousands or millions of years, as material from the protoplanetary disc was added. Both rocky and gaseous planets started with a solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>. Rocky planets built more rock on that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>, while gas planets added gas and ice. Ice giants formed later and on the furthest edges of the disc, accumulating less gas and more ice. That is why the gas-giant planets Jupiter and Saturn are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of mostly hydrogen and helium gas, more than 90%. The ice giants Uranus and Neptune are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of mostly methane ices and only about 20% hydrogen and helium gases.<\/p>\n<figure id=\"attachment_4330\" aria-describedby=\"caption-attachment-4330\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-535 size-medium\" title=\"A. Angelich (NRAO\/AUI\/NSF)\/ALMA (ESO\/NAOJ\/NRAO)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-300x255.jpg\" alt=\"It shows a ring of ice around the star\" width=\"300\" height=\"255\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-300x255.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-1024x870.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-768x652.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-65x55.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-225x191.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis-350x297.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Artists_impression_of_the_water_snowline_around_the_young_star_V883_Orionis.jpg 1280w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-4330\" class=\"wp-caption-text\">This artist\u2019s impression of the water snowline around the young star V883 Orionis, as detected with ALMA.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The planetary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> of the gas giants is clearly different from the rocky planets. Their size is also dramatically different for two reasons: First, the original planetary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a> contained more gases and ices than metals and rocks. There was abundant hydrogen, carbon, oxygen, nitrogen, and less silicon and iron, giving the outer planets more building material. Second, the stronger gravitational pull of these giant planets allowed them to collect large quantities of hydrogen and helium, which could not be collected by weaker gravity of the smaller planets.<\/p>\n<figure id=\"attachment_2515\" aria-describedby=\"caption-attachment-2515\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/02.2_TolucaMeteorite.jpg\"><img decoding=\"async\" class=\"wp-image-83 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-2515\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ATolucaMeteorite.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/02.2_TolucaMeteorite-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbThe meteorite is polished showing the Widmanst\u00e4tten Pattern.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb225&Prime;&gt; A polished fragment of the iron-rich Toluca Meteorite, with octahedral Widmanst\u00e4tten Pattern.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Jupiter\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> gravity further shaped the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> and growth of the inner rocky planets. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1249\">nebula<\/a> started to coalesce into planets, Jupiter\u2019s gravity accelerated the movement of nearby materials, generating destructive collisions rather than constructively gluing material together<\/span><span style=\"font-weight: 400\">. <\/span>These collisions created the asteroid belt, an unfinished planet, located between Mars and Jupiter. This asteroid belt is the source of most <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a><\/strong> that currently impact the Earth. Study of asteroids and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a> help geologist to determine the age of Earth and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> of its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. Jupiter\u2019s gravity may also explain Mars\u2019 smaller mass, with the larger planet consuming material as it migrated from the inner to outer edge of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a><span style=\"font-weight: 400\">.\u00a0<\/span><\/p>\n<h4><span style=\"font-weight: 400\">Pluto and planet definition<\/span><\/h4>\n<figure id=\"attachment_3290\" aria-describedby=\"caption-attachment-3290\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/EightTNOs.png\"><img decoding=\"async\" class=\"wp-image-536 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3290\" class=\"wp-caption-text\">GFDL<\/a>, <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/2.5-2.0-1.0&quot;\">CC BY-SA 2.5-2.0-1.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEightTNOs.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/EightTNOs-300&#215;218.png\u00a0\u00bb alt=\u00a0\u00bbIt shows many objects\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb218&Prime;&gt; Eight largest objects discovered past Neptune.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The outermost part of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> is known as the Kuiper belt, which is a scattering of rocky and icy bodies. Beyond that is the Oort cloud, a zone filled with small and dispersed ice traces. These two locations are where most comets form and continue to orbit, and objects found here have relatively irregular orbits compared to the rest of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a><\/span><span style=\"font-weight: 400\">. <\/span>Pluto, formerly the ninth planet, is located in this region of space. The XXVIth General Assembly of the International Astronomical Union (IAU) stripped Pluto of planetary status in 2006 because scientists discovered an object more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> than Pluto, which they named Eris. The IAU decided against including Eris as a planet, and therefore, excluded Pluto as well. The IAU narrowed the definition of a planet to three criteria: 1) enough mass to have gravitational forces that force it to be rounded, 2) not <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> enough to create <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1250\">fusion<\/a>, and 3) large enough to be in a cleared orbit, free of other planetesimals that should have been incorporated at the time the planet formed. Pluto passed the first two parts of the definition, but not the third. Pluto and Eris are currently classified as dwarf planets.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-49\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-49\" class=\"h5p-iframe\" data-content-id=\"49\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4241\" aria-describedby=\"caption-attachment-4241\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.2-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-537\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.2-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4241\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 28px\">8.3 Hadean Eon<\/span><\/h2>\n<figure id=\"attachment_3270\" aria-describedby=\"caption-attachment-3270\" style=\"width: 232px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/17.18_Geologic_Time_Scale_with_years-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3270 size-medium\" title=\"Image by Belinda Madsen\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/17.18_Geologic_Time_Scale_with_years-1-1.jpg\" alt=\"The Geologic Time Scale with an age of each unit shown by a scale\" width=\"232\" height=\"300\" \/><\/a><figcaption id=\"caption-attachment-3270\" class=\"wp-caption-text\">Geologic Time Scale with ages shown<\/figcaption><\/figure>\n<p>Geoscientists use the geological time scale to assign relative age names to events and rocks, separating major events in Earth\u2019s history based on significant changes as recorded in rocks and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>. This section summarizes the most notable events of each major time interval. For a breakdown on how these time intervals are chosen and organized, see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">chapter 7<\/a>.<\/p>\n<p><span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a>, named after the Greek god and ruler of the underworld Hades, is the oldest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">eon<\/a> and dates from 4.5\u20134.0 billion years ago<\/span><span style=\"font-weight: 400\">. \u00a0<\/span><\/p>\n<figure id=\"attachment_3244\" aria-describedby=\"caption-attachment-3244\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hadean.png\"><img decoding=\"async\" class=\"wp-image-491 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3244\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AHadean.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hadean-300&#215;161.png\u00a0\u00bb alt=\u00a0\u00bbThe surface of Earth is full of volcanoes.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb161&Prime;&gt; Artist&rsquo;s impression of the Earth in the Hadean.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">This time represents Earth\u2019s earliest history, during which the planet was characterized by a partially molten surface, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a>, and asteroid impacts. Several mechanisms made the newly forming Earth incredibly hot: gravitational <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_493\">compression<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2044\">radioactive<\/a> decay, and asteroid impacts. Most of this initial heat still exists inside the Earth. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a> was originally defined as the birth of the planet occurring 4.0 billion years ago and preceding the existence of many rocks and life forms. However, geologists have dated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> at 4.4 billion years, with evidence that liquid water was present<\/span><span style=\"font-weight: 400\">. <\/span><span style=\"font-weight: 400\"> There is possibly even evidence of life existing over 4.0 billion years ago<\/span><span style=\"font-weight: 400\">. However, the most reliable record for early life, the microfossil record, starts at 3.5 billion years ago<\/span><span style=\"font-weight: 400\">. <\/span><\/p>\n<h3><b>8.3.1 Origin of Earth&rsquo;s Crust<\/b><\/h3>\n<figure id=\"attachment_3291\" aria-describedby=\"caption-attachment-3291\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MohoDepth.png\"><img decoding=\"async\" class=\"wp-image-539 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3291\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AMohomap.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MohoDepth-300&#215;167.png\u00a0\u00bb alt=\u00a0\u00bbPlaces with mountain building have a deeper moho.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb167&Prime;&gt; The global map of the depth of the moho, or thickness of the crust.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">As Earth cooled from its molten state, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> started to crystallize and settle resulting in a separation of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> based on density and the creation of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>. The earliest Earth was chiefly molten material and would have been rounded by gravitational forces so it resembled a ball of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1751\">lava<\/a> floating in space. As the outer part of the Earth slowly cooled, the high melting-point <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_221\">Bowen\u2019s Reaction Series<\/a> in <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>) formed solid slabs of early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. These slabs were probably unstable and easily reabsorbed into the liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> until the Earth cooled enough to allow numerous larger fragments to form a thin primitive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. Scientists generally assume this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a> was <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a>, and littered with impacts, much like the Moon\u2019s current <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. There is still some debate over when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a> started, which would have led to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a><\/span><span style=\"font-weight: 400\">. Regardless of this, as Earth cooled and solidified, less dense <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> floated to the surface of the Earth to form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, while the denser <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1009\">ultramafic<\/a> materials sank to form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a> and the highest-density iron and nickel sank into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>. This differentiated the Earth from a homogenous planet into a heterogeneous one with layers of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1009\">ultramafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>, and iron and nickel <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a>.<\/span><\/p>\n<h3><b>8.3.2 Origin of the Moon<\/b><\/h3>\n<figure id=\"attachment_3292\" aria-describedby=\"caption-attachment-3292\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Back_side_of_the_Moon_AS16-3021.jpg\"><img decoding=\"async\" class=\"wp-image-540 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3292\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Back_side_of_the_Moon_AS16-3021-300&#215;298.jpg\u00a0\u00bb alt=\u00a0\u00bbIt looks different then the side we don&rsquo;t normally see.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb298&Prime;&gt; Dark side of the Moon<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Several unique features of Earth\u2019s Moon have prompted scientists to develop the current <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a> about its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a>. The Earth and Moon are tidally locked, meaning that as the Moon orbits, one side always faces the Earth and the opposite side is not visible to us. Also and most importantly, the chemical compositions of the Earth and Moon show nearly identical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">isotope<\/a> ratios<\/span><span style=\"font-weight: 400\"> and volatile content<\/span><span style=\"font-weight: 400\">. <\/span>Apollo missions returned from the Moon with rocks that allowed scientists to conduct very precise comparisons between Moon and Earth rocks. Other bodies in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a> do not share the same degree of similarity and show much higher variability. If the Moon and Earth formed together, this would explain why they are so chemically similar.<\/p>\n<figure id=\"attachment_3293\" aria-describedby=\"caption-attachment-3293\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/ArtistsConceptMoonFormation.jpg\"><img decoding=\"async\" class=\"wp-image-541 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3293\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ArtistsConceptMoonFormation-300&#215;240.jpg\u00a0\u00bb alt=\u00a0\u00bbThe Earth and this object are colliding in a giant explosion.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb240&Prime;&gt; Artist&rsquo;s concept of the giant impact from a Mars-sized object that could have formed the moon.<\/figcaption><\/figure>\n<p>Many ideas have been proposed for the origin of the Moon: The Moon could have been captured from another part of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> and formed in place together with the Earth, or the Moon could have been ripped out of the early Earth. None of proposed explanations can account for all the evidence. The currently prevailing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a> is the <strong>giant-impact <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a><\/strong><span style=\"font-weight: 400\">. <\/span>It proposes a body about half of Earth\u2019s size must have shared at least parts of Earth\u2019s orbit and collided with it, resulting in a violent mixing and scattering of material from both objects. Both bodies would be <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of a combination of materials, with more of the lower density splatter coalescing into the Moon. This may explain why the Earth has a higher density and thicker <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a> than the Moon.<\/p>\n<figure id=\"attachment_4254\" aria-describedby=\"caption-attachment-4254\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-542\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4254\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"NASA | Evolution of the Moon\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/UIKmSQqp8wY?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em><span style=\"font-weight: 400\">Computer simulation of the evolution of the Moon (2 minutes).<\/span><\/em><\/p>\n<h3><b>8.3.3 Origin of Earth\u2019s Water<\/b><\/h3>\n<figure id=\"attachment_3294\" aria-describedby=\"caption-attachment-3294\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Comet_on_7_July_2015_NavCam.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-543 size-medium\" title=\"&quot;ESA\/Rosetta\/NAVCAM,\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-300x300.jpg\" alt=\"Jets are seen coming off of the comet.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-768x768.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Comet_on_7_July_2015_NavCam.jpg 1024w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3294\" class=\"wp-caption-text\">Water vapor leaves comet 67P\/Churyumov\u2013Gerasimenko.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Explanations for the origin of Earth\u2019s water include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> outgassing, comets, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> outgassing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a> for the origin of Earth\u2019s water is that it originated from inside the planet, and emerged via <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> processes as vapor associated with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> eruptions<\/span><span style=\"font-weight: 400\">.\u00a0 Since all <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> eruptions contain some water vapor, at times more than 1% of the volume, these alone could have created Earth\u2019s surface water. Another likely source of water was from space. Comets are a mixture of dust and ice, with some or most of that ice being frozen water. Seemingly dry meteors can contain small but measurable amounts of water, usually trapped in their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> structures<\/span><span style=\"font-weight: 400\">. During heavy bombardment <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">periods<\/a> later in Earth\u2019s history, its cooled surface was pummeled by comets and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a>, which could be why so much water exists above ground. There isn\u2019t a definitive answer for what process is the source of ocean water. Earth\u2019s water isotopically matches water found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a> much better than that of comets<\/span><span style=\"font-weight: 400\">. However, it is hard to know if Earth processes could have changed the water\u2019s isotopic signature over the last 4-plus billion years<\/span><span style=\"font-weight: 400\">. <\/span>It is possible that all three sources contributed to the origin of Earth\u2019s water.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-50\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-50\" class=\"h5p-iframe\" data-content-id=\"50\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4242\" aria-describedby=\"caption-attachment-4242\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.3-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-544\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.3-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4242\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.3 via this QR Code.<\/figcaption><\/figure>\n<h2><strong>8.4 Archean Eon<\/strong><\/h2>\n<figure id=\"attachment_3295\" aria-describedby=\"caption-attachment-3295\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Archean.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-545 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-300x134.png\" alt=\"It shows volcanoes, impacts, and stromatolites.\" width=\"300\" height=\"134\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-300x134.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-1024x459.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-768x344.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-1536x688.png 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-65x29.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-225x101.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean-350x157.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archean.png 2048w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3295\" class=\"wp-caption-text\">Artist&rsquo;s impression of the Archean.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a><\/strong>, which lasted from 4.0\u20132.5 billion years ago, is named after the Greek word for beginning. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">eon<\/a> represents the beginning of the rock record. Although there is current evidence that rocks and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> existed during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a><\/span><span style=\"font-weight: 400\">, <\/span>the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> has a much more robust rock and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><b><\/b><span style=\"font-weight: 400\">8.4.1 Late Heavy Bombardment<\/span><\/h3>\n<figure id=\"attachment_3296\" aria-describedby=\"caption-attachment-3296\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pluto-in-true-color_2x_JPEG-edit-frame.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-546 size-medium\" title=\"NASA, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-300x300.jpg\" alt=\"The smooth plain is different than the cratered surrounding surface.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pluto-in-true-color_2x_JPEG-edit-frame.jpg 600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3296\" class=\"wp-caption-text\">2015 image from NASA&rsquo;s New Horizons probe of Pluto. The lack of impacts found on the Tombaugh Regio (the heart-shaped plain, lower right) has been inferred as being younger than the Late Heavy Bombardment and the surrounding surface due to its lack of impacts.<\/figcaption><\/figure>\n<p>Objects were chaotically flying around at the start of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>, building the planets and moons. There is evidence that after the planets formed, about 4.1\u20133.8 billion years ago, a second large spike of asteroid and comet impacted the Earth and Moon in an event called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1258\">late heavy bombardment<\/a><\/strong><span style=\"font-weight: 400\">. <\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">Meteorites<\/a> and comets in stable or semi-stable orbits became unstable and started impacting objects throughout the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>. In addition, this event is called the lunar cataclysm because most of the Moons craters are from this event. During <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1258\">late heavy bombardment<\/a>, the Earth, Moon, and all planets in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> were pummeled by material from the asteroid and Kuiper belts. Evidence of this bombardment was found within samples collected from the Moon.<\/p>\n<figure id=\"attachment_3297\" aria-describedby=\"caption-attachment-3297\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Lhborbits.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-547 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-300x100.png\" alt=\"It shows 3 pictures.\" width=\"300\" height=\"100\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-300x100.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-1024x342.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-768x256.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-65x22.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-225x75.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits-350x117.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lhborbits.png 1360w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3297\" class=\"wp-caption-text\">Simulation of before, during, and after the late heavy bombardment.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">It is universally accepted that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a> experienced extensive asteroid and comet bombardment at its start; however, some other process must have caused the second increase in impacts hundreds of millions of years later. A leading <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a> blames gravitational <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2181\">resonance<\/a> between Jupiter and Saturn for disturbing orbits within the asteroid and Kuiper belts <\/span>based on a similar process observed in the Eta Corvi star <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1742\">system<\/a><span style=\"font-weight: 400\">.<\/span><\/p>\n<h3><b>8.4.2 Origin of the Continents<\/b><\/h3>\n<figure id=\"attachment_2512\" aria-describedby=\"caption-attachment-2512\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Earth-cutaway-schematic-english.svg_-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-51\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-300x211.png\" alt=\"The crust and lithosphere are on the outside of the Earth and are thin. Below the crust is the mantle and core. Below the lithosphere is the asthenosphere.\" width=\"300\" height=\"211\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-300x211.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-65x46.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-225x158.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1-350x246.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Earth-cutaway-schematic-english.svg_-1.png 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-2512\" class=\"wp-caption-text\">The layers of the Earth. Physical layers include lithosphere and asthenosphere; chemical layers are crust, mantle, and core.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">In order for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a> to work as it does currently, it necessarily must have continents. However, the easiest way to create <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> material is via <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_225\">assimilation<\/a> and differentiation of existing continents (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>). This chicken-and-egg quandary over how continents were made in the first place is not easily answered because of the great age of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> material and how much evidence has been lost during <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonics<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1755\">erosion<\/a>. While the timing and specific processes are still debated, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> action must have brought the first <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> material to the Earth\u2019s surface during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a>, 4.4 billion years ago<\/span><span style=\"font-weight: 400\">. <\/span>This model does not solve the problem of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continent<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a>, since <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_226\">magmatic differentiation<\/a> seems to need thicker <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. Nevertheless, the continents formed by some incremental process during the early history of Earth<span style=\"font-weight: 400\">. The best idea is that density differences allowed lighter <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> materials to float upward and heavier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1009\">ultramafic<\/a> materials and metallic iron to sink. These density differences led to the layering of the Earth, the layers that are now detected by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2165\">seismic<\/a> studies. Early protocontinents accumulated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> materials as developing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>&#8211;<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> processes brought lighter material from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a> to the surface<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3299\" aria-describedby=\"caption-attachment-3299\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fig21oceanocean.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3299 size-medium\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fig21oceanocean-1.gif\" alt=\"The ocean plate subducts beneath a different ocean plate.\" width=\"300\" height=\"173\" \/><\/a><figcaption id=\"caption-attachment-3299\" class=\"wp-caption-text\">Subduction of an oceanic plate beneath another oceanic plate, forming a trench and an island arc. Several island arcs might combine and eventually evolve into a continent.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The first solid evidence of modern <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a> is found at the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a>, indicating at least some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1668\">lithosphere<\/a> must have been in place. This evidence does not necessarily mark the starting point of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a>; remnants of earlier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> activity could have been erased by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1749\">rock cycle<\/a><\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_2523\" aria-describedby=\"caption-attachment-2523\" style=\"width: 419px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/CratonGeolProv.jpg\"><img decoding=\"async\" class=\"wp-image-92\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-2523\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CratonGeolProv-300&#215;159.jpg\u00a0\u00bb alt=\u00a0\u00bbThe legend shows shields, platforms, orogens, basins, large igneous provinces, and extended crust.\u00a0\u00bb width=\u00a0\u00bb419&Prime; height=\u00a0\u00bb222&Prime;&gt; Geologic provinces of Earth. Cratons are pink and orange.<\/figcaption><\/figure>\n<p>The stable interiors of the current continents are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">cratons<\/a><\/strong> and were mostly formed in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a>. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">craton<\/a> has two main parts: the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1259\">shield<\/a><\/strong>, which is crystalline <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1023\">basement<\/a> rock near the surface, and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1260\">platform<\/a><\/strong> made of sedimentary rocks covering the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1259\">shield<\/a>. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">cratons<\/a> have remained relatively unchanged with most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> activity having occurred around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">cratons<\/a> instead of within them. Whether they were created by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">plate tectonics<\/a> or another process, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> continents gave rise to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> continents that now dominate our planet.<\/p>\n<figure id=\"attachment_3300\" aria-describedby=\"caption-attachment-3300\" style=\"width: 258px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Zealandia_topography.jpg\"><img decoding=\"async\" class=\"wp-image-549 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3300\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Zealandia_topography-258&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbIt shows Zealandia\u00a0\u00bb width=\u00a0\u00bb258&Prime; height=\u00a0\u00bb300&Prime;&gt; The continent of Zealandia<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The general guideline as to what constitutes a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continent<\/a> and differentiates <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a> is under some debate. At passive margins, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a> grades into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic crust<\/a> at passive margins, making a distinction difficult<\/span><span style=\"font-weight: 400\">. Even island-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1687\">arc<\/a> and hot-spot material can seem more closely related to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a> than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic<\/a>. Continents usually have a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">craton<\/a> in the middle with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> rocks. There is evidence that submerged masses like Zealandia, that includes present-day New Zealand, would be considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continent<\/a><\/span><span style=\"font-weight: 400\">. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">Continental crust<\/a> that does not contain a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">craton<\/a> is called a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> fragment, such as the island of Madagascar off the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of Africa<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><b>8.4.3 First Life on Earth<\/b><\/h3>\n<figure id=\"attachment_3301\" aria-describedby=\"caption-attachment-3301\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicrobialMats.jpg\"><img decoding=\"async\" class=\"wp-image-550 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3301\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ARunzelmarken.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MicrobialMats-300&#215;167.jpg\u00a0\u00bb alt=\u00a0\u00bbRocks with a wrinkled texture, formed by microbial mats\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb167&Prime;&gt; Fossils of microbial mats from Sweden<\/figcaption><\/figure>\n<p>Life most likely started during the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1255\">Hadean<\/a> or early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eons<\/a>. The earliest evidence of life are chemical signatures, microscopic filaments, and microbial mats. Carbon found in 4.1 billion year old <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1227\">zircon<\/a> grains have a chemical signature suggesting an organic origin. Other evidence of early life are 3.8\u20134.3 billion-year-old microscopic filaments from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1999\">hydrothermal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_234\">vent<\/a> deposit in Quebec, Canada. While the chemical and microscopic filaments evidence is not as robust as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>, there is significant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> evidence for life at 3.5 billion years ago. These first well-preserved <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> are photosynthetic microbial mats, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1265\">stromatolites<\/a>, found in Australia.<\/p>\n<figure id=\"attachment_3302\" aria-describedby=\"caption-attachment-3302\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/15.2_greenhouse-gas-molecules.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-551 size-medium\" title=\"https:\/\/climate.nasa.gov\/system\/internal_resources\/details\/original\/249_Causes-greenhouse-gas-molecules-cropped-more-55.jpg\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-300x192.jpg\" alt=\"Illustration of the molecular shape of greenhouse gases.\" width=\"300\" height=\"192\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-300x192.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-65x42.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-225x144.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules-350x224.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/15.2_greenhouse-gas-molecules.jpg 746w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3302\" class=\"wp-caption-text\">Greenhouse gases were more common in Earth\u2019s early atmosphere.<\/figcaption><\/figure>\n<p>Although the origin of life on Earth is unknown, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypotheses<\/a> include a chemical origin in the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> and ocean, deep-sea <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1999\">hydrothermal<\/a> vents, and delivery to Earth by comets or other objects. One <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a> is that life arose from the chemical environment of the Earth\u2019s early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> and oceans, which was very different than today. The oxygen-free <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> produced a reducing environment with abundant methane, carbon dioxide, sulfur, and nitrogen compounds. This is what the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> is like on other bodies in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1253\">solar system<\/a>. In the famous Miller-Urey <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1731\">experiment<\/a>, researchers simulated early Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> and lightning within a sealed vessel. After igniting sparks within the vessel, they discovered the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a> of amino acids, the fundamental building blocks of proteins.\u00a0 In 1977, when scientists discovered an isolated ecosystem around <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1999\">hydrothermal<\/a> vents on a deep-sea <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridge<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>), it opened the door for another explanation of the origin of life. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1999\">hydrothermal<\/a> vents have a unique ecosystem of critters with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_231\">chemosynthesis<\/a> as the foundation of the food chain instead of photosynthesis. The ecosystem is deriving its energy from hot chemical-rich waters pouring out of underground towers. This suggests that life could have started on the deep <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1963\">ocean floor<\/a> and derived energy from the heat from the Earth\u2019s interior via <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_231\">chemosynthesis<\/a>. Scientists have since expanded the search for life to more unconventional places, like Jupiter\u2019s icy moon Europa.<\/p>\n<figure id=\"attachment_4244\" aria-describedby=\"caption-attachment-4244\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.4.3-Animation-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-552\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4.3-Animation-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4244\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this animation via this QR Code.<\/figcaption><\/figure>\n<div style=\"width: 854px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-601-1\" width=\"854\" height=\"480\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/webm\" src=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2017\/03\/Miller-Urey_experiment_-_Work_by_the_C3BC_consortium_licensed_under_CC-BY-3.0.webm.480p.webm?_=1\" \/><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2017\/03\/Miller-Urey_experiment_-_Work_by_the_C3BC_consortium_licensed_under_CC-BY-3.0.webm.480p.webm\">http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2017\/03\/Miller-Urey_experiment_-_Work_by_the_C3BC_consortium_licensed_under_CC-BY-3.0.webm.480p.webm<\/a><\/video><\/div>\n<p><em>Animation of the original Miller-Urey 1959 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1731\"><em>experiment<\/em><\/a> that simulated the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\"><em>atmosphere<\/em><\/a> and created amino acids from simple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\"><em>elements<\/em><\/a> and compounds. <\/em><\/p>\n<p>Another possibility is that life or its building blocks came to Earth from space, carried aboard comets or other objects. Amino acids, for example, have been found within comets and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a>. This intriguing possibility also implies a high likelihood of life existing elsewhere in the cosmos.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-51\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-51\" class=\"h5p-iframe\" data-content-id=\"51\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4243\" aria-describedby=\"caption-attachment-4243\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.4-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-553\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.4-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4243\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.4 via this QR Code.<\/figcaption><\/figure>\n<h2><strong><span style=\"font-size: 28px\">8.5 Proterozoic Eon<\/span><\/strong><\/h2>\n<figure id=\"attachment_3303\" aria-describedby=\"caption-attachment-3303\" style=\"width: 216px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Photosynthesis.gif\"><img decoding=\"async\" class=\"wp-image-554 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3303\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3APhotosynthesis.gif&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Photosynthesis-216&#215;300.gif\u00a0\u00bb alt=\u00a0\u00bbWater and carbon dioxide go into plants, making sugar and oxygen.\u00a0\u00bb width=\u00a0\u00bb216&Prime; height=\u00a0\u00bb300&Prime;&gt; Diagram showing the main products and reactants in photosynthesis. The one product that is not shown is sugar, which is the chemical energy that goes into constructing the plant, and the energy that is stored in the plant which is used later by the plant or by animals that consume the plant.<\/figcaption><\/figure>\n<p>The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a><\/strong>, meaning \u201cearlier life,\u201d comes after the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a> and ranges from 2.5 billion to 541 million years old. During this time, most of the central parts of the continents had formed and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> processes had started. Photosynthesis by microbial organisms, such as single-celled cyanobacteria, had been slowly adding oxygen to the oceans. As cyanobacteria evolved into multicellular organisms, they completely transformed the oceans and later the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> by adding <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> amounts of free oxygen gas (O<sub>2<\/sub>) and initiated what is called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1262\">Great Oxygenation Event<\/a> (GOE<\/strong>). This drastic environmental change decimated the anaerobic bacteria, which could not survive in the presence of free oxygen. On the other hand, aerobic organisms could thrive in ways they could not earlier<span style=\"font-weight: 400\">. <\/span><\/p>\n<p>An oxygenated world also changed the chemistry of the planet in significant ways. For example, iron remained in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> in the non-oxygenated environment of the earlier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a>. In chemistry, this is known as a reducing environment. Once the environment was oxygenated, iron combined with free oxygen to form solid precipitates of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a>, such as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> hematite or magnetite. These precipitates accumulated into large <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> deposits with red <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1927\">chert<\/a> known as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2009\">banded<\/a>-iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formations<\/a>, which are dated at about 2 billion years<span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3304\" aria-describedby=\"caption-attachment-3304\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MichiganBIF-1.jpg\"><img decoding=\"async\" class=\"wp-image-371 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3304\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MichiganBIF-1-300&#215;206.jpg\u00a0\u00bb alt=\u00a0\u00bbThe rock shows red and brown layering.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb206&Prime;&gt; Alternating bands of iron-rich and silica-rich mud, formed as oxygen combined with dissolved iron.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a> of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and red <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1927\">chert<\/a> (see figure) in the oceans lasted a long time and prevented oxygen levels from increasing significantly, since <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> took the oxygen out of the water and deposited it into the rock <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1935\">strata<\/a>. As oxygen continued to be produced and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> leveled off, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> oxygen gas eventually <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1784\">saturated<\/a> the oceans and started bubbling out into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a>. Oxygenation of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> is the single biggest event that distinguishes the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> environments. In addition to changing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> and ocean chemistry, the GOE is also tabbed as triggering Earth\u2019s first <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">glaciation<\/a> event around 2.1 billion years ago, the Huron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">Glaciation<\/a>. Free oxygen reacted with methane in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> to produce carbon dioxide. Carbon dioxide and methane are called greenhouse gases because they trap heat within the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a>, like the insulated glass of a greenhouse. Methane is a more effective insulator than carbon dioxide, so as the proportion of carbon dioxide in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> increased, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_762\">greenhouse effect<\/a> decreased, and the planet cooled.<\/p>\n<h3><b>8.5.1 Rodinia<\/b><\/h3>\n<figure id=\"attachment_3305\" aria-describedby=\"caption-attachment-3305\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Rodinia_reconstruction.jpg\"><img decoding=\"async\" class=\"wp-image-555 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3305\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rodinia_reconstruction-300&#215;267.jpg\u00a0\u00bb alt=\u00a0\u00bbThe image shows the continents arrange in a possible orientation of Rodinia.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb267&Prime;&gt; One possible reconstruction of Rodinia 1.1 billion years ago. Source: John Goodge, modified from (Dalziel 1997).<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">By the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a>, lithospheric plates had formed and were moving according to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> forces that were similar to current times. As the moving <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plates<\/a> collided, the ocean basins closed to form a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinent<\/a><\/strong> called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1263\">Rodinia<\/a><\/strong>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinent<\/a> formed about 1 billion years ago and broke up about 750 to 600 million years ago, at the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a><\/span><span style=\"font-weight: 400\">. <\/span>One of the resulting fragments was a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> mass called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1264\">Laurentia<\/a><\/strong> that would later become North America. Geologists have reconstructed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1263\">Rodinia<\/a> by matching and aligning ancient mountain chains, assembling the pieces like a jigsaw puzzle, and using paleomagnetics to orient to magnetic north.<\/p>\n<p><span style=\"font-weight: 400\">The disagreements over these complex reconstructions is exemplified by geologists proposing at least six different models for the breakup of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1263\">Rodinia<\/a> to create Australia<\/span><span style=\"font-weight: 400\">, Antarctica<\/span><span style=\"font-weight: 400\">, parts of China<\/span><span style=\"font-weight: 400\">, the Tarim <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">craton<\/a> north of the Himalaya<\/span><span style=\"font-weight: 400\">, Siberia<\/span><span style=\"font-weight: 400\">, or the Kalahari <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1718\">craton<\/a> of eastern Africa<\/span><span style=\"font-weight: 400\">. <\/span>This breakup created lots of shallow-water, biologically favorable environments that fostered the evolutionary breakthroughs marking the start of the next <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">eon<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a>.<\/p>\n<p>&nbsp;<\/p>\n<h3><b>8.5.2 Life Evolves<\/b><\/h3>\n<figure id=\"attachment_3306\" aria-describedby=\"caption-attachment-3306\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Stromatolites_in_Sharkbay.jpg\"><img decoding=\"async\" class=\"wp-image-556 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3306\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStromatolites_in_Sharkbay.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Stromatolites_in_Sharkbay-300&#215;223.jpg\u00a0\u00bb alt=\u00a0\u00bbPicture of modern cyanobacteria (as stromatolites) in Shark Bay, Australia. The brown, blobby stromatolites are slightly sticking out of the shallow water of the ocean.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb223&Prime;&gt; Modern cyanobacteria (as stromatolites) in Shark Bay, Australia.<\/figcaption><\/figure>\n<p>Early life in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1257\">Archean<\/a> and earlier is poorly documented in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record. Based on chemical evidence and evolutionary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1733\">theory<\/a>, scientists propose this life would have been single-celled photosynthetic organisms, such as the cyanobacteria that created <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1265\">stromatolites<\/a><\/strong>. Cyanobacteria produced free oxygen in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a> through photosynthesis. Cyanobacteria, archaea, and bacteria are <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1266\">prokaryotes<\/a><\/strong>\u2014primitive organisms made of single cells that lack cell nuclei and other organelles.<\/p>\n<figure id=\"attachment_3307\" aria-describedby=\"caption-attachment-3307\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Stromatolites_hoyt.jpg\"><img decoding=\"async\" class=\"wp-image-557 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3307\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AStromatolites_hoyt_mcr1.JPG&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Stromatolites_hoyt-300&#215;200.jpg\u00a0\u00bb alt=\u00a0\u00bbRound structures of grey limestone are remnants of the blobby nature of the living stromatolites, fossilized in rock.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb200&Prime;&gt; Fossil stromatolites in Saratoga Springs, New York.<\/figcaption><\/figure>\n<p>A large evolutionary step occurred during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a> with the appearance of <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1267\">eukaryotes<\/a><\/strong> around 2.1 to 1.6 billion years ago. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1267\">Eukaryotic<\/a> cells are more complex, having nuclei and organelles. The nuclear DNA is capable of more complex replication and regulation than that of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1266\">prokaryotic<\/a> cells. The organelles include mitochondria for producing energy and chloroplasts for photosynthesis. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1267\">eukaryote<\/a> branch in the tree of life gave rise to fungi, plants, and animals.<\/p>\n<p>Another important event in Earth\u2019s biological history occurred about 1.2 billion years ago when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1267\">eukaryotes<\/a> invented sexual reproduction. Sharing genetic material from two reproducing individuals, male and female, greatly increased genetic variability in their offspring. This genetic mixing accelerated evolutionary change, contributing to more complexity among individual organisms and within ecosystems (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/7-geologic-time\/\">Chapter 7<\/a>).<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> land surfaces were barren of plants and animals and geologic processes actively shaped the environment differently because land surfaces were not protected by leafy and woody vegetation. For example, rain and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2212\">rivers<\/a> would have caused <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1755\">erosion<\/a> at much higher rates on land surfaces devoid of plants. This resulted in thick accumulations of pure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1912\">sandstone<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a> such as the extensive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2013\">quartzite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formations<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1667\">core<\/a> of the Uinta Mountains in Utah.<\/p>\n<figure id=\"attachment_3308\" aria-describedby=\"caption-attachment-3308\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/DickinsoniaCostata.jpg\"><img decoding=\"async\" class=\"wp-image-558 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3308\" class=\"wp-caption-text\">Verisimilus<\/a> at <a href=\"denied:&quot;https:\/\/en.wikipedia.org\/wiki\/&quot;\" class=\"&quot;extiw&quot;\" title=\"&quot;wikipedia:&quot;\">English Wikipedia<\/a> [<a href=\"denied:&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a>, <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by\/2.5&quot;\">CC BY 2.5<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADickinsoniaCostata.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/DickinsoniaCostata-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbThe fossil is a flat, leaf-shaped\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb225&Prime;&gt; Dickinsonia, a typical Ediacaran fossil.<\/figcaption><\/figure>\n<p>Fauna during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1268\">Ediacaran<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>, 635.5 to 541 million years ago are known as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1268\">Ediacaran fauna<\/a><\/strong>, and offer a first glimpse at the diversity of ecosystems that evolved near the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a>. These soft-bodied organisms were among the first multicellular life forms and probably were similar to jellyfish or worm-like. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1268\">Ediacaran fauna<\/a> did not have hard parts like shells and were not well preserved in the rock records. However, studies suggest they were widespread in the Earth\u2019s oceans. Scientists still debate how many species were evolutionary dead-ends that became <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinct<\/a> and how many were ancestors of modern groupings. The transition of soft-bodied <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1268\">Ediacaran<\/a> life to life forms with hard body parts occurred at the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> and beginning of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eons<\/a>. This evolutionary explosion of biological diversity made a dramatic difference in scientists\u2019 ability to understand the history of life on Earth.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-52\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-52\" class=\"h5p-iframe\" data-content-id=\"52\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.5 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4245\" aria-describedby=\"caption-attachment-4245\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.5-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-559\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.5-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4245\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.5 via this QR Code.<\/figcaption><\/figure>\n<h2><strong>8.6 Phanerozoic Eon: Paleozoic Era<\/strong><\/h2>\n<figure id=\"attachment_3249\" aria-describedby=\"caption-attachment-3249\" style=\"width: 243px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/ElrathiakingiUtahWheelerCambrian.jpg\"><img decoding=\"async\" class=\"wp-image-497 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3249\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/ElrathiakingiUtahWheelerCambrian-243&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbIt has three lobes\u00a0\u00bb width=\u00a0\u00bb243&Prime; height=\u00a0\u00bb300&Prime;&gt; The trilobites had a hard exoskeleton, and is an early arthropod, the same group that includes modern insects, crustaceans, and arachnids.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a><\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">Eon<\/a> is the most recent, 541 million years ago to today, <\/span>and means \u201cvisible life\u201d because the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a> rock record is marked by an abundance of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a> organisms had hard body parts like claws, scales, shells, and bones that were more easily preserved as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>. Rocks from the older <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1270\">Precambrian<\/a> time are less commonly found and rarely include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> because these organisms had soft body parts. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a> rocks are younger, more common, and contain the majority of extant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>. The study of rocks from this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1242\">eon<\/a> yields much greater detail. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1269\">Phanerozoic<\/a> is subdivided into three <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">eras<\/a>, from oldest to youngest they are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> (\u201cancient life\u201d), <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> (\u201cmiddle life\u201d), and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> (\u201crecent life\u201d) and the remaining three chapter headings are on these three important <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">eras<\/a>.<\/p>\n<figure id=\"attachment_3309\" aria-describedby=\"caption-attachment-3309\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Trilobite_Heinrich_Harder.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-560 size-medium\" title=\"Trilobites, by Heinrich Harder, 1916.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-300x186.jpg\" alt=\"The trilobites are crawling over the sea floor\" width=\"300\" height=\"186\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-300x186.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-65x40.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-225x140.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder-350x217.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Trilobite_Heinrich_Harder.jpg 650w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3309\" class=\"wp-caption-text\">Trilobites, by Heinrich Harder, 1916.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Life in the early <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a><\/strong> was dominated by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> organisms but by the middle of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a> plants and animals evolved to live and reproduce on land. Fish evolved jaws and fins evolved into jointed limbs. The development of lungs allowed animals to emerge from the sea and become the first air-breathing tetrapods (four-legged animals) such as amphibians. From amphibians evolved reptiles with the amniotic egg. From reptiles evolved an early ancestor to birds and mammals <\/span><span style=\"font-weight: 400\">and their scales became feathers and fur. Near the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_475\">Carboniferous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a> had some of the most extensive forests in Earth\u2019s history. Their fossilized remains became the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1934\">coal<\/a> that powered the industrial revolution<\/span><\/p>\n<h3><strong>8.6.1 Paleozoic Tectonics and Paleogeography<\/strong><\/h3>\n<figure id=\"attachment_3310\" aria-describedby=\"caption-attachment-3310\" style=\"width: 256px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/North_america_craton_nps.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-561 size-medium\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-256x300.gif\" alt=\"It is a map of North America\" width=\"256\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-256x300.gif 256w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-65x76.gif 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-225x263.gif 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/North_america_craton_nps-350x409.gif 350w\" sizes=\"auto, (max-width: 256px) 100vw, 256px\" \/><\/a><figcaption id=\"caption-attachment-3310\" class=\"wp-caption-text\">Laurentia, which makes up the North American craton.<\/figcaption><\/figure>\n<p>During the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>, sea-levels rose and fell four times. With each sea-level rise, the majority of North America was covered by a shallow tropical ocean. Evidence of these submersions are the abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> sedimentary rocks such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a> with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> corals and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1923\">ooids<\/a>. Extensive sea-level <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2197\">falls<\/a> are documented by widespread <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2039\">unconformities<\/a>. Today, the midcontinent has extensive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> sedimentary rocks from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> and western North America has thick layers of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a> on block faulted mountain ranges such as Mt. Timpanogos near Provo, Utah<span style=\"font-weight: 400\">.\u00a0<\/span><\/p>\n<figure id=\"attachment_3311\" aria-describedby=\"caption-attachment-3311\" style=\"width: 267px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pangaea_continents.png\"><img decoding=\"async\" class=\"wp-image-3311 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3311\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3APangaea_continents.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangaea_continents-1.png\u00a0\u00bb alt=\u00a0\u00bbPangaea has a crescent shape.\u00a0\u00bb width=\u00a0\u00bb267&Prime; height=\u00a0\u00bb300&Prime;&gt; A reconstruction of Pangaea, showing approximate positions of modern continents.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The assembly of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinent<\/a> <strong>Pangea<\/strong>, sometimes spelled Pangaea, was completed by the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>. The name Pangea was originally coined by Alfred Wegener and means \u201call land.\u201d Pangea is the when all of the major continents were grouped together as one by a series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> events including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> island-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1687\">arc<\/a> accretion, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> collisions, and ocean-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_508\">basin<\/a> closures. In North America, these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> events occurred on the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> and are known as the Taconic, Acadian, Caledonian, and Alleghanian orogenies<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\"> The Appalachian Mountains are the erosional remnants of these mountain building events in North America. Surrounding Pangea was a global ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_508\">basin<\/a> known as the Panthalassa. Continued <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> movement extended the ocean into Pangea, forming a large bay called the Tethys Sea that eventually divided the land mass into two smaller <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinents<\/a>, Laurasia and Gondwana. Laurasia consisted of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1264\">Laurentia<\/a> and Eurasia, and Gondwana consisted of the remaining continents of South America, Africa, India, Australia, and Antarctica. <\/span><\/p>\n<figure id=\"attachment_4254\" aria-describedby=\"caption-attachment-4254\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-542\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/NASA-Evolution-of-the-Moon-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4254\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-3\" title=\"Continental Drift\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/ovT90wYrVk4?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em>Animation of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\"><em>plate<\/em><\/a> movement the last 3.3 billion years. <em>Pangea<\/em> occurs at the 4:40 mark.<\/em><\/p>\n<p>While the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of North America was tectonically active during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>, the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> remained mostly inactive as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1676\">passive margin<\/a> during the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a>. The western edge of North American <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continent<\/a> was near the present-day Nevada-Utah border and was an expansive shallow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1969\">continental shelf<\/a> near the paleoequator. However, by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1279\">Devonian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>, the Antler <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a> started on the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> and lasted until the Pennsylvanian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>. The Antler <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a> was a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1697\">island arc<\/a> that was accreted onto western North America with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> direction away from North America. This created a mountain range on the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of North American called the Antler highlands and was the first part of building the land in the west that would eventually make most of California, Oregon, and Washington states. By the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a>, the Sonoma <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a> began on the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> and was another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collision<\/a> of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1697\">island arc<\/a>. The Sonoma <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a> marks the change in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> direction to be toward North America with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1695\">volcanic arc<\/a> along the entire west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of North America by late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> to early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Eras<\/a><span style=\"font-weight: 400\">.<\/span><\/p>\n<p>By the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>, the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of North America had a very high mountain range due to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collision<\/a> and the creation of Pangea. The west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of North America had smaller and isolated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> highlands associated with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1697\">island arc<\/a> accretion. During the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a>, the size of the mountains on either side of North America would flip, with the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> being a more tectonically active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1670\">plate boundary<\/a> and the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> changing into a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1676\">passive margin<\/a> after the breakup of Pangea.<\/p>\n<h3><strong>8.6.2 Paleozoic Evolution<\/strong><\/h3>\n<figure id=\"attachment_3312\" aria-describedby=\"caption-attachment-3312\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Anomalocaris.jpg\"><img decoding=\"async\" class=\"wp-image-563 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3312\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AAnomalocaris_canadensis_-_reconstruction_-_MUSE.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Anomalocaris-300&#215;200.jpg\u00a0\u00bb alt=\u00a0\u00bbThe animal has two arms and large eyes.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb200&Prime;&gt; Anomalocaris reconstruction by the MUSE science museum in Italy.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The beginning of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a> is marked by the first appearance of hard body parts like shells, spikes, teeth, and scales; and the appearance in the rock record of most animal phyla known today. That is, most basic animal body plans appeared in the rock record during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>. This sudden appearance of biological diversity is called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1272\">Cambrian Explosion<\/a>. <\/strong>Scientists debate whether this sudden appearance is more from a rapid evolutionary diversification as a result of a warmer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a> following the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1261\">Proterozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1988\">glacial<\/a> environments, better preservation and fossilization of hard parts, or artifacts of a more complete and recent rock record. For example, fauna may have been diverse during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1268\">Ediacaran<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>, setting the state for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1272\">Cambrian Explosion<\/a>, but they lacked hard body parts and would have left few <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> behind<\/span><span style=\"font-weight: 400\">. Regardless, during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a> 541\u2013485 million years ago marked the appearance of most animal phyla<\/span><span style=\"font-weight: 400\">. <\/span><\/p>\n<figure id=\"attachment_3313\" aria-describedby=\"caption-attachment-3313\" style=\"width: 112px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Opabinia.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-564 size-medium\" title=\"&quot;Charles\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-112x300.jpg\" alt=\"The animal has a long trunk with claws at the end.\" width=\"112\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-112x300.jpg 112w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-381x1024.jpg 381w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-65x175.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-225x604.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia-350x940.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Opabinia.jpg 446w\" sizes=\"auto, (max-width: 112px) 100vw, 112px\" \/><\/a><figcaption id=\"caption-attachment-3313\" class=\"wp-caption-text\">Original plate from Walcott&rsquo;s 1912 description of Opabinia, with labels: fp = frontal appendage, e = eye, ths = thoracic somites, i = intestine, ab = abdominal segment.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">One of the best <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> sites for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1272\">Cambrian Explosion<\/a> was discovered in 1909 by <a href=\"http:\/\/www.nasonline.org\/member-directory\/deceased-members\/20000936.html\">Charles Walcott (1850\u20131927)<\/a> in the <strong>Burgess <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1917\">Shale<\/a><\/strong> in western Canada. The Burgess <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1917\">Shale<\/a> is a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1273\">Lagerst\u00e4tte<\/a><\/strong>, a site of exceptional <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> preservation that includes impressions of soft body parts. This discovery allowed scientists to study <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> animals in immense detail because soft body parts are not normally preserved and fossilized. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1273\">Lagerst\u00e4tte<\/a> sites of similar age in China and Utah have allowed scientist to form a detailed picture of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> biodiversity. The biggest mystery surrounds animals that do not fit existing lineages and are unique to that time. This includes many famous fossilized creatures: the first compound-eyed trilobites; <em>Wiwaxia<\/em>, a creature covered in spiny <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plates<\/a>;<em> Hallucigenia<\/em>, a walking worm with spikes;<em> Opabinia<\/em>, a five-eyed arthropod with a grappling claw; and <em>Anomalocaris<\/em>, the alpha predator of its time, complete with grasping appendages and circular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1776\">mouth<\/a> with sharp <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plates<\/a><\/span><span style=\"font-weight: 400\">. <\/span>Most notably appearing during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> is an important ancestor to humans. A segmented worm called <em>Pikaia<\/em> is thought to be the earliest ancestor of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">Chordata<\/a><\/strong> phylum that includes <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrates<\/a>, animals with backbones<span style=\"font-weight: 400\">.\u00a0<\/span><\/p>\n<figure id=\"attachment_3314\" aria-describedby=\"caption-attachment-3314\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Coral_Outcrop_Flynn_Reef-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-565\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-300x225.jpg\" alt=\"The reef has many intricacies.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coral_Outcrop_Flynn_Reef-1.jpg 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3314\" class=\"wp-caption-text\">A modern coral reef.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>By the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a>, mollusks, brachiopods, nautiloids, gastropods, graptolites, echinoderms, and trilobites covered the sea floor. Although most animal phyla appeared by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a>, the biodiversity at the family, genus, and species level was low until the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1277\">Ordovician<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a>. During the <strong>Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1277\">Ordovician<\/a> Biodiversification Event<\/strong>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrates<\/a> and invertebrates (animals without backbone) became more diverse and complex at family, genus, and species level. The cause of the rapid speciation event is still debated but some likely causes are a combination of warm temperatures, expansive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> shelves near the equator, and more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> along the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridges<\/a>. Some have shown evidence that an asteroid breakup event and consequent heavy <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorite<\/a> impacts correlate with this diversification event. The additional <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> added nutrients to ocean water helping support a robust ecosystem. Many life forms and ecosystems that would be recognizable in current times appeared at this time. Mollusks, corals, and arthropods in particular multiplied to dominate the oceans<span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3315\" aria-describedby=\"caption-attachment-3315\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Guadalupe_Nima2.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-566 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-300x206.jpg\" alt=\"The entire mountain is one big fossil.\" width=\"300\" height=\"206\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-300x206.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-1024x701.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-768x526.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-1536x1052.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-65x45.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-225x154.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2-350x240.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Guadalupe_Nima2.jpg 1600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3315\" class=\"wp-caption-text\">Guadalupe National Park is made of a giant fossil reef.<\/figcaption><\/figure>\n<p>One important evolutionary advancement during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1277\">Ordovician<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a> was <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1976\">reef<\/a>-building organisms, mostly colonial coral. Corals took advantage of the ocean chemistry, using <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> to build large structures that resembled modern <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1976\">reefs<\/a> like the Great Barrier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1976\">Reef<\/a> off the coast of Australia. These reefs housed thriving ecosystems of organisms that swam around, hid in, and crawled over them. Reefs are important to paleontologists because of their preservation potential, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> size, and in-place ecosystems. Few other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> offer more diversity and complexity than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1976\">reef<\/a> assemblages<span style=\"font-weight: 400\">.<\/span><\/p>\n<p><span style=\"font-weight: 400\">According to evidence from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1988\">glacial<\/a> deposits,\u00a0 a small <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">ice age<\/a> caused sea-levels to drop and led to a major <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> by the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1277\">Ordovician<\/a>. This is the earliest of five <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a><\/strong> events documented in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record. During this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a>, an unusually large number of species abruptly disappear in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record (see video).\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\">Life bounced back during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1278\">Silurian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a><\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\">\u00a0The major evolutionary event was the development of the forward pair of gill arches into jaws, allowing fish new feeding strategies and opening up new ecological niches.<\/span><\/p>\n<figure id=\"attachment_4253\" aria-describedby=\"caption-attachment-4253\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/How-Many-Mass-Extinctions-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-567\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/How-Many-Mass-Extinctions-Youtube-QR-Code.png 1148w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4253\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-4\" title=\"How Many Mass Extinctions Have There Been?\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/aO9mOAKXvJs?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em>3-minute video describing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\"><em>mass extinctions<\/em><\/a> and how they are\u00a0defined.<\/em><\/p>\n<figure id=\"attachment_3316\" aria-describedby=\"caption-attachment-3316\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Placoderm.jpg\"><img decoding=\"async\" class=\"wp-image-568 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3316\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0&quot;\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABothriolepis_panderi.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Placoderm-300&#215;264.jpg\u00a0\u00bb alt=\u00a0\u00bbThis fish is covered with armor.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb264&Prime;&gt; The placoderm Bothriolepis panderi from the Devonian of Russia<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Life bounced back during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1278\">Silurian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>\u2019s major evolutionary event was the development of jaws from the forward pair of gill arches in bony fishes and sharks. Hinged jaws allowed fish to exploit new food sources and ecological niches. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a> also included the start of armored fishes, known as the placoderms. In addition to fish and jaws, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1278\">Silurian<\/a> rocks provide the first evidence of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> or land-dwelling plants and animals<\/span><span style=\"font-weight: 400\">. The first vascular plant, <em>Cooksonia,<\/em> had woody tissues, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2194\">pores<\/a> for gas exchange, and veins for water and food transport<\/span><span style=\"font-weight: 400\">. Insects, spiders, scorpions, and crustaceans began to inhabit moist, freshwater <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> environments<\/span><span style=\"font-weight: 400\">. \u00a0<\/span><\/p>\n<figure id=\"attachment_3317\" aria-describedby=\"caption-attachment-3317\" style=\"width: 392px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fishapods.png\"><img decoding=\"async\" class=\"wp-image-569\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3317\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/4.0-3.0-2.5-2.0-1.0&quot;\">CC BY-SA 4.0-3.0-2.5-2.0-1.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFishapods.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fishapods-300&#215;153.png\u00a0\u00bb alt=\u00a0\u00bbSix different fish\/amphibians are shown, with variation between totally swimming and fully walking.\u00a0\u00bb width=\u00a0\u00bb392&Prime; height=\u00a0\u00bb200&Prime;&gt; Several different types of fish and amphibians that led to walking on land.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1279\">Devonian<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">Period<\/a> is called the Age of Fishes due to the rise in plated, jawed, and lobe-finned fishes . The lobe-finned fishes, which were related to the modern lungfish and coelacanth, are important for their eventual evolution into tetrapods, four-limbed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrate<\/a> animals that can walk on land. \u00a0The first lobe-finned land-walking fish, named <em>Tiktaalik<\/em>, appeared about 385 million years ago and serves as a transition <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> between fish and early tetrapods<\/span><span style=\"font-weight: 400\">. <\/span>Though Tiktaalik was clearly a fish, it had some tetrapod structures as well. Several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1279\">Devonian<\/a> are more tetrapod like than fish like but these weren\u2019t fully <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a>. The first fully <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> tetrapod arrived in the Mississippian (early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_475\">Carboniferous<\/a>) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>. By the Mississippian (early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_475\">Carboniferous<\/a>) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>, tetrapods had evolved into two main groups, amphibians and amniotes, from a common tetrapod ancestor. The amphibians were able to breathe air and live on land but still needed water to nurture their soft eggs. The first reptile (an amniote) could live and reproduce entirely on land with hard-shelled eggs that wouldn\u2019t dry out.<\/p>\n<p><span style=\"font-weight: 400\">\u00a0Land plants had also evolved into the first trees and forests<\/span><span style=\"font-weight: 400\">. Toward the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1279\">Devonian<\/a>, another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> event occurred. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a>, while severe, is the least temporally defined, with wide variations in the timing of the event or events. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1976\">Reef<\/a> building organisms were the hardest hit, leading to dramatic changes in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> ecosystems<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3318\" aria-describedby=\"caption-attachment-3318\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Arthropleura.png\"><img decoding=\"async\" class=\"wp-image-570 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3318\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArthropleura.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Arthropleura-300&#215;156.png\u00a0\u00bb alt=\u00a0\u00bbThe millipede is about 2 meters long.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb156&Prime;&gt; A reconstruction of the giant arthropod (insects and their relatives) Arthropleura.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The next time <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>, called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_475\">Carboniferous<\/a> (North American geologists have subdivided this into the Mississippian and Pennsylvanian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">periods<\/a>), saw the highest levels of oxygen ever known, with forests (e.g., ferns, club mosses) and swamps dominating the landscape <\/span><span style=\"font-weight: 400\">. This helped cause\u00a0the largest arthropods ever<\/span><span style=\"font-weight: 400\">, like the millipede <\/span><i><span style=\"font-weight: 400\">Arthropleura<\/span><\/i><span style=\"font-weight: 400\">, at 2.5 meters (6.4 feet) long! It also saw the rise of a new group of animals, the reptiles. The evolutionary advantage that reptiles have over amphibians is the amniote egg (egg with a protective shell), which allows them to rely on non-aquatic environments for reproduction. This widened the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> reach of reptiles compared to amphibians. This booming life, especially plant life, created cooling temperatures as carbon dioxide<\/span><span style=\"font-weight: 400\">\u00a0was removed from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a><\/span><span style=\"font-weight: 400\">. By the middle <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_475\">Carboniferous<\/a>, these cooler temperatures led to an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">ice age<\/a> (called the Karoo <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">Glaciation<\/a>) and less-productive forests. The reptiles fared much better than the amphibians, leading to their diversification<\/span><span style=\"font-weight: 400\">. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1988\">glacial<\/a> event lasted into the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_476\">Permian<\/a><\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3319\" aria-describedby=\"caption-attachment-3319\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dimetrodon_grandis.jpg\"><img decoding=\"async\" class=\"wp-image-571 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3319\" class=\"wp-caption-text\">DiBgd<\/a> at <a href=\"denied:&quot;https:\/\/en.wikipedia.org\/wiki\/&quot;\" class=\"&quot;extiw&quot;\" title=\"&quot;wikipedia:&quot;\">English Wikipedia<\/a> [<a href=\"denied:&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a>, <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by\/2.5&quot;\">CC BY 2.5<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ADimetrodon_grandis.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dimetrodon_grandis-300&#215;169.jpg\u00a0\u00bb alt=\u00a0\u00bbThe animal has a large mouth with sharp teeth and a large sail on its back.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb169&Prime;&gt; Reconstruction of Dimetrodon.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">By the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_476\">Permian<\/a>, with Pangea assembled, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinent<\/a> led to a dryer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a>, and even more diversification and domination by the reptiles<\/span><span style=\"font-weight: 400\">. The groups that developed in this warm <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a> eventually radiated into dinosaurs. Another group, known as the synapsids, eventually evolved into mammals<\/span><span style=\"font-weight: 400\">. Synapsids, including the famous sail-backed <\/span><i><span style=\"font-weight: 400\">Dimetrodon<\/span><\/i><span style=\"font-weight: 400\"> are commonly confused with dinosaurs.<\/span><span style=\"font-weight: 400\">\u00a0Pelycosaurs (of the Pennsylvanian to early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_476\">Permian<\/a> like <\/span><i><span style=\"font-weight: 400\">Dimetrodon) <\/span><\/i><span style=\"font-weight: 400\">are the first group of synapsids that exhibit the beginnings of mammalian characteristics such as well-differentiated dentition: incisors, highly developed canines in lower and upper jaws and cheek teeth, premolars and molars. Starting in the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_476\">Permian<\/a>, a second group of synapsids, called the therapsids (or mammal-like reptiles) evolve<\/span><span style=\"font-weight: 400\">, and become the ancestors to mammals.<\/span><\/p>\n<h4><span style=\"font-weight: 400\">Permian Mass Extinction<\/span><\/h4>\n<figure id=\"attachment_2911\" aria-describedby=\"caption-attachment-2911\" style=\"width: 399px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/World-map-or-flood-basalts.jpg\"><img decoding=\"async\" class=\"wp-image-307\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-2911\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFlood_Basalt_Map.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/World-map-or-flood-basalts-300&#215;168.jpg\u00a0\u00bb alt=\u00a0\u00bbWorld map of flood basalts. Note the largest is the Siberian Traps\u00a0\u00bb width=\u00a0\u00bb399&Prime; height=\u00a0\u00bb223&Prime;&gt; World map of flood basalts. Note the largest is the Siberian Traps<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a> is marked by the largest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> in earth history. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a> had two smaller <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinctions<\/a>, \u00a0but these were not as large as the <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_477\">Permian Mass Extinction<\/a><\/b><span style=\"font-weight: 400\">, also known as the <\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_477\">Permian-Triassic Extinction Event<\/a><span style=\"font-weight: 400\">. It is estimated that up to 96% of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> species and 70% of land-dwelling (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a>) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrates<\/a> went extinct<\/span><span style=\"font-weight: 400\">. Many famous organisms, like sea scorpions and trilobites, were never seen again in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record. <\/span><span style=\"font-weight: 400\">What caused such a widespread <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> event? The exact cause is still debated, though the leading idea relates to extensive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> associated with the <strong>Siberian Traps<\/strong>, which are one of the largest deposits of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_244\">flood basalts<\/a> known on Earth, dating to the time of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> event<\/span><span style=\"font-weight: 400\">. The eruption size is estimated at over 3 million cubic kilometers<\/span><span style=\"font-weight: 400\"> that is approximately 4,000,000 times larger than the famous 1980 Mt. St. Helens eruption in Washington. \u00a0The unusually large <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> eruption would have contributed a large amount of toxic gases, aerosols, and greenhouse gasses into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a>. Further, some evidence suggests that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> burned vast <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1934\">coal<\/a> deposits releasing methane (a greenhouse gas) into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a><\/span><span style=\"font-weight: 400\">. As discussed in <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/15-global-climate-change\/\">Chapter 15<\/a>, greenhouse gases cause the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a> to warm. This extensive addition of greenhouse gases from the Siberian Traps may have caused a runaway <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_762\">greenhouse effect<\/a> that rapidly changed the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a>, acidified the oceans, disrupted food chains, disrupted carbon cycling, and caused the largest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a><\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-53\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-53\" class=\"h5p-iframe\" data-content-id=\"53\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.6 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4248\" aria-describedby=\"caption-attachment-4248\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Video-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-572\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4248\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this interactive activity via this QR Code.<\/figcaption><\/figure>\n<h2><b>8.7 Phanerozoic Eon: Mesozoic Era<\/b><\/h2>\n<figure id=\"attachment_3321\" aria-describedby=\"caption-attachment-3321\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Fighting_dinosaurs.jpg\"><img decoding=\"async\" class=\"wp-image-573 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3321\" class=\"wp-caption-text\">CC BY 2.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AFighting_dinosaurs_(1).jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Fighting_dinosaurs-300&#215;173.jpg\u00a0\u00bb alt=\u00a0\u00bbThe dinosaurs are fighting\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb173&Prime;&gt; Perhaps the greatest fossil ever found, a velociraptor attacked a protoceratops, and both were fossilized mid sequence.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Following the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_477\">Permian Mass Extinction<\/a>, the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a><\/strong> (\u00ab\u00a0middle life\u00a0\u00bb) was from 252 million years ago to 66 million years ago. As Pangea started to break apart, mammals, birds, and flowering plants developed. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> is probably best known as the age of reptiles, most notably, the dinosaurs.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">8.7.1 Mesozoic Tectonics and Paleogeography<\/span><\/h3>\n<figure id=\"attachment_3322\" aria-describedby=\"caption-attachment-3322\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pangea_animation_03.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-574\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pangea_animation_03.gif\" alt=\"The continents separate into their current configuration.\" width=\"200\" height=\"160\" \/><\/a><figcaption id=\"caption-attachment-3322\" class=\"wp-caption-text\">Animation showing Pangea breaking up<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Pangea started breaking up (in a region that would become eastern Canada and United States) around 210 \u00a0million years ago in the Late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a><\/span><span style=\"font-weight: 400\">. Clear evidence for this includes the age of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediments<\/a> in the Newark Supergroup <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1702\">rift<\/a> basins and the Palisades <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1022\">sill<\/a> of the eastern part of North America and the age of the Atlantic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1963\">ocean floor<\/a>. Due to sea-floor spreading, the oldest rocks on the Atlantic\u2019s floor are along the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of northern Africa and the east coast of \u00a0North America, while the youngest are along the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridge<\/a>.<\/span><\/p>\n<figure id=\"attachment_3323\" aria-describedby=\"caption-attachment-3323\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/age_oceanic_lith.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3323 size-medium\" title=\"Image via NOAA https:\/\/www.ngdc.noaa.gov\/mgg\/ocean_age\/data\/2008\/image\/age_oceanic_lith.jpg\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/age_oceanic_lith-1.jpg\" alt=\"The map shoes colors that represent different ages.\" width=\"300\" height=\"191\" \/><\/a><figcaption id=\"caption-attachment-3323\" class=\"wp-caption-text\">Age of oceanic lithosphere, in millions of years. Notice the differences in the Atlantic Ocean along the coasts of the continents.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">This age pattern shows how the Atlantic Ocean opened as the young Mid-Atlantic Ridge began to create the seafloor. This means the Atlantic ocean started opening and was first formed here. The southern Atlantic opened next, with South America separating from central and southern Africa. Last (happening after the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> ended) was the northernmost Atlantic, with Greenland and Scandinavia parting ways.\u00a0<\/span><span style=\"font-weight: 400\">The breaking points of each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1702\">rifted<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> margin eventually turned into the passive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> boundaries of the east <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of the Americas today.<\/span><\/p>\n<figure id=\"attachment_4248\" aria-describedby=\"caption-attachment-4248\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Video-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-572\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Video-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4248\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this interactive activity via this QR Code.<\/figcaption><\/figure>\n<div style=\"width: 300px;\" class=\"wp-video\"><video class=\"wp-video-shortcode\" id=\"video-601-2\" width=\"300\" height=\"200\" preload=\"metadata\" controls=\"controls\"><source type=\"video\/mp4\" src=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/PangeaEADef.mp4?_=2\" \/><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/PangeaEADef.mp4\">http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/PangeaEADef.mp4<\/a><\/video><\/div>\n<p><em><a href=\"http:\/\/emvc.geol.ucsb.edu\/2_infopgs\/IP1GTect\/aPangeaAnim.html\">Video<\/a> of <em>Pangea<\/em> breaking apart and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\"><em>plates<\/em><\/a> moving to their present locations. By Tanya Atwater.<\/em><\/p>\n<figure id=\"attachment_3324\" aria-describedby=\"caption-attachment-3324\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sevierorogeny.jpg\"><img decoding=\"async\" class=\"wp-image-576 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3324\" class=\"wp-caption-text\">CC0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASevierorogeny.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Sevierorogeny-300&#215;113.jpg\u00a0\u00bb alt=\u00a0\u00bbIt shows faulting and a volcanic arc\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb113&Prime;&gt; Sketch of the major features of the Sevier Orogeny.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In western North America, an active <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> margin had started with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a>, controlling most of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonics<\/a> of that region in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a>. Another possible island-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1687\">arc<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collision<\/a> created the Sonoman <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">Orogeny<\/a> in Nevada during the latest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a><\/span><span style=\"font-weight: 400\">. In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>, another island-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1687\">arc<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collision<\/a> caused the Nevadan <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">Orogeny<\/a>, a large Andean-style <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1695\">volcanic arc<\/a> and thrust belt<\/span><span style=\"font-weight: 400\">. The Sevier Orogeny followed in the Cretaceous, which was mainly a volcanic arc to the west and a thin-skinned fold and thrust belt to the east<\/span><span style=\"font-weight: 400\">, meaning stacks of shallow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2143\">faults<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_502\">folds<\/a> built up the topography. Many of the structures in the Rocky Mountains today date from this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a>.<\/span><\/p>\n<figure id=\"attachment_3325\" aria-describedby=\"caption-attachment-3325\" style=\"width: 250px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cretaceous_seaway.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-577 size-full\" title=\"USGS, public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Cretaceous_seaway.png\" alt=\"Water is covering the middle of North America.\" width=\"250\" height=\"301\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Cretaceous_seaway.png 250w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Cretaceous_seaway-65x78.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Cretaceous_seaway-225x271.png 225w\" sizes=\"auto, (max-width: 250px) 100vw, 250px\" \/><\/a><figcaption id=\"caption-attachment-3325\" class=\"wp-caption-text\">The Cretaceous Interior Seaway in the mid-Cretaceous.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">Tectonics<\/a> had an influence in one more important geographic feature in North America: the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">Cretaceous<\/a> Western Interior Foreland <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_508\">Basin<\/a>, which flooded during high sea levels forming the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_480\">Cretaceous\u00a0Interior Seaway<\/a><\/strong>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">Subduction<\/a> from the west was the Farallon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">Plate<\/a>, an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> connected to the Pacific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">Plate<\/a> (seen today as remnants such as the Juan de Fuca <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">Plate<\/a>, off the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of the Pacific Northwest). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">Subduction<\/a> was shallow at this time because a very young, hot and less dense portion of the Farallon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> was <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducted<\/a>. This shallow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> caused a downwarping in the central part of North America<\/span><span style=\"font-weight: 400\">. High sea levels due to shallow <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a>, and increasing rates of seafloor spreading and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a>, high temperatures, and melted ice also contributed to the high sea levels<\/span><span style=\"font-weight: 400\">. These factors allowed a shallow epicontinental seaway that extended from the Gulf of Mexico to the Arctic Ocean to divide North America into two separate land masses<\/span><span style=\"font-weight: 400\">, Laramidia to the west and Appalachia to the east, for 25 million years<\/span><span style=\"font-weight: 400\">. Many of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1934\">coal<\/a> deposits in Utah and Wyoming formed from swamps along the shores of this seaway<\/span><span style=\"font-weight: 400\">. By the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">Cretaceous<\/a>, cooling temperatures caused the seaway to regress<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">8.7.2 Mesozoic Evolution<\/span><\/h3>\n<figure id=\"attachment_3326\" aria-describedby=\"caption-attachment-3326\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Mesozoic_Scene.jpg\"><img decoding=\"async\" class=\"wp-image-578 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3326\" class=\"wp-caption-text\">CC BY-SA 2.5<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AEuropasaurus_holgeri_Scene_2.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Mesozoic_Scene-300&#215;225.jpg\u00a0\u00bb alt=\u00a0\u00bbSeveral dinosaurs and their relatives are in the scene.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb225&Prime;&gt; A Mesozoic scene from the late Jurassic.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a> is dominated by reptiles, and more specifically, the dinosaurs. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a> saw devastated ecosystems that took over 30 million years to fully re-emerge after the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_477\">Permian Mass Extinction<\/a><\/span><span style=\"font-weight: 400\">. \u00a0The first appearance of many modern groups of animals that would later flourish occurred at this time. \u00a0This includes frogs (amphibians), turtles (reptiles), <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> ichthyosaurs and plesiosaurs (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> reptiles), mammals, and the archosaurs. \u00a0The archosaurs (\u201cruling reptiles\u201d) include ancestral groups that went <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinct<\/a> at the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a>, as well as the flying pterosaurs, crocodilians, and the dinosaurs. \u00a0Archosaurs, like the placental mammals after them, occupied all major environments: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> (dinosaurs), in the air (pterosaurs), aquatic (crocodilians) and even fully <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> habitats (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> crocodiles). The pterosaurs, the first <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrate<\/a>\u00a0group to take flight, like the dinosaurs and mammals, start small in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a>.<\/span><\/p>\n<figure id=\"attachment_3327\" aria-describedby=\"caption-attachment-3327\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Augustasaurus_BW.jpg\"><img decoding=\"async\" class=\"wp-image-579 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3327\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by\/3.0&quot;\">CC BY 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AAugustasaurus_BW.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Augustasaurus_BW-300&#215;189.jpg\u00a0\u00bb alt=\u00a0\u00bbIt is a swimming reptile with a long neck\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb189&Prime;&gt; A drawing of the early plesiosaur Agustasaurus from the Triassic of Nevada.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">At the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a><\/span><span style=\"font-weight: 400\">, another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> event occurred, the fourth major <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> in the geologic record. This was perhaps caused by the Central Atlantic Magmatic Province <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_244\">flood basalt<\/a><\/span><span style=\"font-weight: 400\">. The end-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> made certain lineages go extinct and helped spur the evolution of survivors like mammals, pterosaurs (flying reptiles), ichthyosaurs\/plesiosaurs\/mosasaurs (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> reptiles), and dinosaurs<\/span><span style=\"font-weight: 400\">. <\/span><\/p>\n<figure id=\"attachment_3328\" aria-describedby=\"caption-attachment-3328\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Megazostrodon_sp._Natural_History_Museum_-_London.jpg\"><img decoding=\"async\" class=\"wp-image-580 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3328\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AMegazostrodon_sp._Natural_History_Museum_-_London.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Megazostrodon_sp._Natural_History_Museum_-_London-300&#215;200.jpg\u00a0\u00bb alt=\u00a0\u00bbIt is small, less than 5 inches, and looks like a shrew\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb200&Prime;&gt; Reconstruction of the small (&lt;5&Prime;) Megazostrodon, one of the first animals considered to be a true mammal.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Mammals, as previously mentioned, got their start from a reptilian synapsid ancestor possibly in the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a><\/span><span style=\"font-weight: 400\">. Mammals stayed small, in mainly nocturnal niches, with insects being their largest prey. The development of warm-blooded circulation and fur may have been a response to this lifestyle<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3329\" aria-describedby=\"caption-attachment-3329\" style=\"width: 226px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ornithischia.png\"><img decoding=\"async\" class=\"wp-image-581\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3329\" class=\"wp-caption-text\">GFDL<\/a> or <a href=\"denied:&quot;http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\/&quot;\">CC-BY-SA-3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AOrnithischia.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ornithischia-150&#215;150.png\u00a0\u00bb alt=\u00a0\u00bbThe bones of the pubis and ischium are close to each other.\u00a0\u00bb width=\u00a0\u00bb226&Prime; height=\u00a0\u00bb186&Prime;&gt; Closed structure of a ornithischian hip, which is similar to a birds.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>, species that were previously common, flourished due to a warmer and more tropical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a><\/span><span style=\"font-weight: 400\">. The dinosaurs were relatively small animals in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a>, but became truly <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>. \u00a0Dinosaurs are split into two groups based on their hip structure<\/span><span style=\"font-weight: 400\">, i.e. orientation of the pubis and ischium bones in relationship to each other. \u00a0This is referred to as the \u201creptile hipped\u201d saurischians and the \u201cbird hipped\u201d ornithischians. This has recently been brought into question by a new idea for dinosaur lineage.<\/span><\/p>\n<figure id=\"attachment_3330\" aria-describedby=\"caption-attachment-3330\" style=\"width: 227px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Saurischia.png\"><img decoding=\"async\" class=\"wp-image-582\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3330\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ASaurischia_pelvis_structure.svg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Saurischia.png\u00a0\u00bb alt=\u00a0\u00bbThe bones of the pubis and ischium are away from each other.\u00a0\u00bb width=\u00a0\u00bb227&Prime; height=\u00a0\u00bb214&Prime;&gt; Open structure of a saurischian hip, which is similar to a lizards.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Most of the dinosaurs of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_485\">Triassic<\/a> were saurischians, but all of them were bipedal. The major adaptive advantage dinosaurs had was changes in the hip and ankle bones, tucking the legs under the body for improved locomotion as opposed to the semi-erect gait of crocodiles or the sprawling posture of reptiles. In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>, limbs (or a lack thereof) were also important to another group of reptiles, leading to the evolution of <\/span><i><span style=\"font-weight: 400\">Eophis<\/span><\/i><span style=\"font-weight: 400\">, the oldest snake<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3331\" aria-describedby=\"caption-attachment-3331\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Beipiao1mmartyniuk.png\"><img decoding=\"async\" class=\"wp-image-583 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3331\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABeipiao1mmartyniuk.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Beipiao1mmartyniuk-300&#215;158.png\u00a0\u00bb alt=\u00a0\u00bbIt is a feathered dinosaur with large hand claws\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb158&Prime;&gt; Therizinosaurs, like Beipiaosaurus (shown in this restoration), are known for their enormous hand claws.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">There is a paucity of dinosaur <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> from the Early and Middle <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a><\/span><span style=\"font-weight: 400\">, but by the Late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a> they were dominating the planet<\/span><span style=\"font-weight: 400\">. The saurischians diversified into the giant herbivorous (plant-eating) long-necked sauropods weighing up to 100 tons and bipedal carnivorous theropods, with the possible exception of the <\/span><i><span style=\"font-weight: 400\">Therizinosaurs<\/span><\/i><span style=\"font-weight: 400\">. All of the ornithischians (e.g <\/span><i><span style=\"font-weight: 400\">Stegosaurus, Iguanodon, Triceratops, Ankylosaurus,\u00a0<\/span><\/i><i>Pachycephhlosaurus<\/i>) were herbivorous with a strong tendency to have a \u201cturtle-like\u201d beak at the tips of their mouths.<\/p>\n<figure id=\"attachment_2488\" aria-describedby=\"caption-attachment-2488\" style=\"width: 222px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/09\/Archaeopteryx_lithographica_Berlin_specimen.jpg\"><img decoding=\"async\" class=\"wp-image-54 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-2488\" class=\"wp-caption-text\">CC BY-SA 3.0<\/a> or <a href=\"denied:&quot;http:\/\/www.gnu.org\/copyleft\/fdl.html&quot;\">GFDL<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArchaeopteryx_lithographica_(Berlin_specimen).jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Archaeopteryx_lithographica_Berlin_specimen-222&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbThe fossil has bird and dinosaur features.\u00a0\u00bb width=\u00a0\u00bb222&Prime; height=\u00a0\u00bb300&Prime;&gt; Iconic \u201cBerlin specimen\u201d Archaeopteryx lithographica fossil from Germany.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The pterosaurs grew and diversified in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>, and another notable arial organism developed and thrived in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a>: birds. When <\/span><i><span style=\"font-weight: 400\">Archeopteryx<\/span><\/i><span style=\"font-weight: 400\"> was found in the Solnhofen <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1273\">Lagerst\u00e4tte<\/a> of Germany<\/span><span style=\"font-weight: 400\">, a seeming dinosaur-bird hybrid, it started the conversation on the origin of birds. The idea that birds evolved from dinosaurs occurred very early in the history of research into evolution, only a few years after Darwin\u2019s <\/span><i><span style=\"font-weight: 400\">On the Origin of Species<\/span><\/i><span style=\"font-weight: 400\">. This study used a remarkable <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> of <\/span><i><span style=\"font-weight: 400\">Archeopteryx<\/span><\/i><span style=\"font-weight: 400\"> from a transitional animal between dinosaurs and birds. Small meat-eating theropod dinosaurs were likely the branch that became birds due to their similar features<\/span><span style=\"font-weight: 400\">. A significant debate still exists over how and when powered flight evolved. Some have stated a running-start model<\/span><span style=\"font-weight: 400\">, while others have favored a tree-leaping gliding model<\/span><span style=\"font-weight: 400\"> or even a semi-combination: flapping to aid in climbing<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3333\" aria-describedby=\"caption-attachment-3333\" style=\"width: 199px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Argentinosaurus_DSC_2943.jpg\"><img decoding=\"async\" class=\"wp-image-584 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3333\" class=\"wp-caption-text\">GFDL 1.2<\/a> or <a href=\"denied:&quot;http:\/\/artlibre.org\/licence\/lal\/en&quot;\">FAL<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AArgentinosaurus_DSC_2943.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Argentinosaurus_DSC_2943-199&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbThe dinosaur is huge! 130&prime; long and 24&prime; high.\u00a0\u00bb width=\u00a0\u00bb199&Prime; height=\u00a0\u00bb300&Prime;&gt; Reconstructed skeleton of Argentinosaurus, from Naturmuseum Senckenberg in Germany.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">Cretaceous<\/a> saw a further diversification, specialization, and domination of the dinosaurs and other fauna. One of the biggest changes on land was the transition to angiosperm-dominated flora. Angiosperms, which are plants with flowers and seeds, had originated in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">Cretaceous<\/a><\/span><span style=\"font-weight: 400\">, switching many plains to grasslands by the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a><\/span><span style=\"font-weight: 400\">. By the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>, they had replaced gymnosperms (evergreen trees) and ferns as the dominant plant in the world\u2019s forests. Haplodiploid eusocial insects (bees and ants) are descendants from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_486\">Jurassic<\/a> wasp-like ancestors that co-evolved with the flowering plants during this time <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a><\/span><span style=\"font-weight: 400\">. The breakup of Pangea not only shaped our modern world\u2019s geography, but biodiversity at the time as well. Throughout the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a>, animals on the isolated, now separated island continents (formerly parts of Pangea), took strange evolutionary turns. This includes giant titanosaurian sauropods (<\/span><i><span style=\"font-weight: 400\">Argentinosaurus<\/span><\/i><span style=\"font-weight: 400\">) and theropods (<\/span><i><span style=\"font-weight: 400\">Giganotosaurus<\/span><\/i><span style=\"font-weight: 400\">) from South America<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<h4><span style=\"font-weight: 400\">K-T Extinction<\/span><\/h4>\n<figure id=\"attachment_3334\" aria-describedby=\"caption-attachment-3334\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Extinction_intensity.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-585 size-medium\" title=\"After: Raup, D. &amp; Sepkoski, J. (1982). &quot;Mass extinctions in the marine fossil record&quot;. Science 215: 1501\u20131503. DOI:10.1126\/science.215.4539.1501. Rohde, R.A. &amp; Muller, R.A. (2005). &quot;Cycles in fossil diversity&quot;. Nature 434: 209-210. DOI:10.1038\/nature03339. Sepkoski, J. (2002) A Compendium of Fossil Marine Animal Genera (eds. Jablonski, D. &amp; Foote, M.) Bull. Am. Paleontol. no. 363 (Paleontological Research Institution, Ithaca, NY). Signor, P. and J. Lipps (1982) &quot;Sampling bias, gradual extinction patterns and catastrophes in the fossil record&quot;, in Geologic Implications of Impacts of Large Asteroids and Comets on the Earth, I. Silver and P. Silver Eds, Geol. Soc. Amer. Special Paper 190, Boulder Colo. p. 291-296.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-300x183.png\" alt=\"There are many spikes, but the K\/T spike is second largest to the end Perlman.\" width=\"300\" height=\"183\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-300x183.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-1024x625.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-768x469.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-65x40.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-225x137.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_-350x214.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Extinction_intensity.svg_.png 1062w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3334\" class=\"wp-caption-text\">Graph of the rate of extinctions. Note the large spike at the end of the Cretaceous (labeled as K).<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Similar to the end of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1271\">Paleozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">Era<\/a> ended with the <\/span><b>K-Pg <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">Mass Extinction<\/a> <\/b><span style=\"font-weight: 400\">(previously known as the <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_481\">K-T Extinction<\/a><\/b><span style=\"font-weight: 400\">) 66 million years ago<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\"> This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> event was likely caused by a large <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_482\">bolide<\/a> <\/b>(<span style=\"font-weight: 400\">an extraterrestrial impactor such as an asteroid, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteoroid<\/a>, or comet) that collided with earth<\/span><span style=\"font-weight: 400\">. Ninety percent of plankton species, 75% of plant species, and all the dinosaurs went <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinct<\/a> at this time.<\/span><\/p>\n<figure id=\"attachment_3335\" aria-describedby=\"caption-attachment-3335\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Impact_event.jpg\"><img decoding=\"async\" class=\"wp-image-586 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3335\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Impact_event-300&#215;209.jpg\u00a0\u00bb alt=\u00a0\u00bbThe rock is slamming into the Earth\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb209&Prime;&gt; Artist&rsquo;s depiction of an impact event<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">One of the strongest pieces of evidence comes from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> iridium. Quite rare on Earth, and more common in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1254\">meteorites<\/a>, it has been found all over the world in higher concentrations at a particular layer of rock that formed at the time of the K-T boundary. Soon other scientists started to find evidence to back up the claim. Melted rock spheres<\/span><span style=\"font-weight: 400\">, a special type of \u201cshocked\u201d <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> called stishovite, that only is found at impact sites, was found in many places around the world <\/span><span style=\"font-weight: 400\">. T<\/span><span style=\"font-weight: 400\">he huge impact created a strong thermal pulse that could be responsible for global forest fires<\/span><span style=\"font-weight: 400\">, strong acid rains<\/span><span style=\"font-weight: 400\">, a corresponding abundance of ferns, the first colonizing plants after a forest fire<\/span><span style=\"font-weight: 400\">, enough debris thrown into the air to significantly cool temperatures afterward<\/span><span style=\"font-weight: 400\">, and a 2-km high tsunami inferred from deposits found from Texas to Alabama<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3336\" aria-describedby=\"caption-attachment-3336\" style=\"width: 268px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Chicxulub_radar_topography.jpg\"><img decoding=\"async\" class=\"wp-image-587 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3336\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Chicxulub_radar_topography-268&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbThe crater is circular.\u00a0\u00bb width=\u00a0\u00bb268&Prime; height=\u00a0\u00bb300&Prime;&gt; The land expression of the Chicxulub crater. The other side of the crater is within the Gulf of M\u00e9xico.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Still, with all this evidence, one large piece remained missing: the crater where the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_482\">bolide<\/a> impacted. It was not until 1991 <\/span><span style=\"font-weight: 400\">that the crater was confirmed using petroleum company geophysical data. Even though it is the third largest confirmed crater on Earth at roughly 180 km wide, the <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_483\">Chicxulub Crater<\/a><\/b><span style=\"font-weight: 400\"> was hard to find due to being partially underwater and partially obscured by the dense forest canopy of the Yucatan Peninsula<\/span><span style=\"font-weight: 400\">. Coring of the center of the impact called the peak ring contained <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1014\">granite<\/a>, indicating the impact was so powerful that it lifted <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1023\">basement<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediment<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a> several miles toward the surface<\/span><span style=\"font-weight: 400\">. In 2010, an international team of scientists reviewed 20 years of research and blamed the impact for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a><\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3337\" aria-describedby=\"caption-attachment-3337\" style=\"width: 298px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/India_Geology_Zones.jpg\"><img decoding=\"async\" class=\"wp-image-588 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3337\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/India_Geology_Zones-298&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbIt covers more than 200,000 square miles\u00a0\u00bb width=\u00a0\u00bb298&Prime; height=\u00a0\u00bb300&Prime;&gt; Geology of India, showing purple as Deccan Traps-related rocks.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">With all of this information, it seems like the case would be closed. However, there are other events at this time which could have partially aided the demise of so many organisms. For example, sea levels are known to be slowly decreasing at the time of the K-T event, which is tied to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> extinctions<\/span><span style=\"font-weight: 400\">, though any study on gradual vs. sudden changes in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record is flawed due to the incomplete nature of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record<\/span><span style=\"font-weight: 400\">. <\/span><span style=\"font-weight: 400\">Another big event at this time was the <\/span><b>Deccan Traps<\/b><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_244\">flood basalt<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> in India. At over 1.3 million cubic kilometers of material, it was certainly a large source of material hazardous to ecosystems at the time, and it has been suggested as at least partially responsible for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a><\/span><span style=\"font-weight: 400\">. Some have found the impact and eruptions too much of a coincidence, and have even linked the two together<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-54\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-54\" class=\"h5p-iframe\" data-content-id=\"54\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.7 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4247\" aria-describedby=\"caption-attachment-4247\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.7-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-589\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.7-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4247\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.7 via this QR Code.<\/figcaption><\/figure>\n<h2><strong>8.8 Phanerozoic Eon: Cenozoic Era<\/strong><\/h2>\n<figure id=\"attachment_3338\" aria-describedby=\"caption-attachment-3338\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Paracertherium.png\"><img decoding=\"async\" class=\"wp-image-590 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3338\" class=\"wp-caption-text\">CC BY-SA 4.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3AIndricotherium.png&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Paracertherium-300&#215;234.png\u00a0\u00bb alt=\u00a0\u00bbIt is grey and tall.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb234&Prime;&gt; Paraceratherium, seen in this reconstruction, was a massive (15-20 ton, 15 foot tall) ancestor of rhinos.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a><\/strong>, meaning \u201cnew life,\u201d is known as the age of mammals because it is in this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1243\">era<\/a> that mammals came to be a dominant and large life form, including human ancestors. Birds, as well, flourished in the open niches left by the dinosaur\u2019s demise. Most of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> has been relatively warm, with the main exception being the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">ice age<\/a> that started about 2.558 million years ago and (despite recent warming) continues today<\/span><span style=\"font-weight: 400\">. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">Tectonic<\/a> shifts in the west caused <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a>, but eventually changed the long-standing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> zone into a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\">transform<\/a> boundary.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">8.8.1 Cenozoic Tectonics and Paleogeography<\/span><\/h3>\n<figure id=\"attachment_4255\" aria-describedby=\"caption-attachment-4255\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Plate-Tectonics-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-4255\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Plate-Tectonics-Youtube-QR-Code-1.png\" alt=\"\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-4255\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<p><iframe loading=\"lazy\" id=\"oembed-5\" title=\"Plate Tectonics in a Nutshell (Tanya Atwater)\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/IDTBY5WDELg?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>&nbsp;<\/p>\n<p><em>Animation of the last 38 million years of movement in western North America. Note, that after the ridge is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\"><em>subducted<\/em><\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1678\"><em>convergent<\/em><\/a> turns to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\"><em>transform<\/em><\/a> (with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1677\"><em>divergent<\/em><\/a> inland).<\/em><\/p>\n<figure id=\"attachment_3339\" aria-describedby=\"caption-attachment-3339\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Shallow_subduction_Laramide_orogeny.png\"><img decoding=\"async\" class=\"wp-image-3339 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3339\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Shallow_subduction_Laramide_orogeny-1.png\u00a0\u00bb alt=\u00a0\u00bbThe subducting plate goes right under the overriding plate\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb142&Prime;&gt; Shallow subduction during the Laramide Orogeny.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plates<\/a> of the Earth moved into more familiar places, with the biggest change being the closing of the Tethys Sea with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collisions<\/a> such as the Alps, Zagros, and Himalaya, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1698\">collision<\/a> that started about 57 million years ago, and continues today<\/span><span style=\"font-weight: 400\">. Maybe the most significant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> feature that occurred in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> of North America was the conversion of the west <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of California from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1678\">convergent<\/a> boundary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> zone to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\">transform<\/a> boundary. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">Subduction<\/a> off the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1968\">coast<\/a> of the western United States, which had occurred throughout the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a>, had continued in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a>. After the Sevier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">Orogeny<\/a> in the late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_479\">Mesozoic<\/a>, a subsequent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a> called the Laramide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">Orogeny<\/a>, occurred in the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a><\/span><span style=\"font-weight: 400\">. The Laramide was <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1690\">thick-skinned<\/a>, different than the Sevier <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">Orogeny<\/a>. It involved deeper crustal rocks, and produced bulges that would become mountain ranges like the Rockies, Black Hills, Wind <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2212\">River<\/a> Range, Uinta Mountains, and the San Rafael Swell. Instead of descending directly into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> shallowed out and moved eastward beneath the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> affecting the overlying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continent<\/a> hundreds of miles east of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> margin and building high mountains.\u00a0 This occurred because the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> was so young and near the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">spreading center<\/a> and the density of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> was therefore low and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> was hindered.\u00a0<\/span><\/p>\n<figure id=\"attachment_3340\" aria-describedby=\"caption-attachment-3340\" style=\"width: 217px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Sanandreas.jpg\"><img decoding=\"async\" class=\"wp-image-3340 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3340\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Sanandreas-1.jpg\u00a0\u00bb alt=\u00a0\u00bbThe fault runs through California.\u00a0\u00bb width=\u00a0\u00bb217&Prime; height=\u00a0\u00bb300&Prime;&gt; Map of the San Andreas fault, showing relative motion.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridge<\/a> itself started to subduct, the relative motion had changed. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">Subduction<\/a> caused a relative convergence between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducting<\/a> Farallon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> and the North American <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>. On the other side of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridge<\/a> from the Farallon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> was the Pacific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>, which was moving away from the North American <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>. Thus, as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> zone consumed the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1708\">mid-ocean ridge<\/a>, the relative movement became <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\">transform<\/a> instead of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1678\">convergent<\/a>, which went on to become the San Andreas Fault System<\/span><span style=\"font-weight: 400\">. As the San Andreas grew, it caused east-west directed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_492\">extensional<\/a> forces to spread over the western United States, creating the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1514\">Basin and Range<\/a> province<\/span><span style=\"font-weight: 400\">. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\">transform<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2143\">fault<\/a> switched position over the last 18 million years, twisting the mountains around Los Angeles<\/span><span style=\"font-weight: 400\">, and new <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2143\">faults<\/a> in the southeastern California deserts may become a future San Andreas-style <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2143\">fault<\/a><\/span><span style=\"font-weight: 400\">. During this switch from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a> to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1679\">transform<\/a>, the nearly horizontal Farallon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1683\">slab<\/a> began to sink into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>. This caused magmatism as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducting<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1683\">slab<\/a> sank, allowing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1671\">asthenosphere<\/a> material to rise around it. This event is called the Oligocene ignimbrite flare-up, which was one of the most significant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">periods<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanism<\/a> ever<\/span><span style=\"font-weight: 400\">, including the largest single confirmed eruption, the 5000 cubic kilometer Fish Canyon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1005\">Tuff<\/a><\/span><span style=\"font-weight: 400\">. <\/span><\/p>\n<h3><span style=\"font-weight: 400\">8.8.2 Cenozoic Evolution<\/span><\/h3>\n<figure id=\"attachment_3341\" aria-describedby=\"caption-attachment-3341\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hominidae_chart.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-594 size-medium\" title=\"&quot;By\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-300x101.png\" alt=\"Humans are most replated to Pan (chimpanzee)\" width=\"300\" height=\"101\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-300x101.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-768x259.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-65x22.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-225x76.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_-350x118.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hominidae_chart.svg_.png 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3341\" class=\"wp-caption-text\">Family tree of Hominids (Hominadae).<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">There are five groups of early mammals in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> record, based primarily on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> teeth, the hardest bone in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrate<\/a> skeletons<\/span><span style=\"font-weight: 400\">. For the purpose of this text, the most important group are the Eupantotheres, that diverge into the two main groups of mammals, the marsupials (like <\/span><i><span style=\"font-weight: 400\">Sinodelphys<\/span><\/i><span style=\"font-weight: 400\">) and placentals or eutherians (like <\/span><i><span style=\"font-weight: 400\">Eomaia<\/span><\/i><span style=\"font-weight: 400\">) in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">Cretaceous<\/a> and then diversified in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a>. \u00a0The marsupials dominated on the isolated island continents of South America and Australia, and many went <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinct<\/a> in South America with the introduction of placental mammals. Some well-known mammal groups have been highly studied with interesting evolutionary stories in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a>. For example, horses started small with four toes, ended up larger and having just one toe<\/span><span style=\"font-weight: 400\">. Cetaceans (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> mammals like whales and dolphins) started on land from small bear-like (mesonychids) creatures in the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> and gradually took to water<\/span><span style=\"font-weight: 400\">. However, no study of evolution has been more studied than human evolution. <\/span><b>Hominids<\/b><span style=\"font-weight: 400\">, the name for human-like primates, started in eastern Africa several\u00a0million years ago.<\/span><\/p>\n<figure id=\"attachment_3342\" aria-describedby=\"caption-attachment-3342\" style=\"width: 199px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Lucy_Skeleton.jpg\"><img decoding=\"async\" class=\"wp-image-595 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3342\" class=\"wp-caption-text\">CC BY-SA 2.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ALucy_Skeleton.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Lucy_Skeleton-199&#215;300.jpg\u00a0\u00bb alt=\u00a0\u00bbThe fossil is about 1\/2 complete\u00a0\u00bb width=\u00a0\u00bb199&Prime; height=\u00a0\u00bb300&Prime;&gt; Lucy skeleton, showing real fossil (brown) and reconstructed skeleton (white).<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The first critical event in this story is an environmental change from jungle to more of a savanna<\/span><span style=\"font-weight: 400\">, probably caused by changes in Indian Ocean circulation. While bipedalism is known to have evolved before this shift<\/span><span style=\"font-weight: 400\">, it is generally believed that our bipedal ancestors (like <\/span><i><span style=\"font-weight: 400\">Australopithecus<\/span><\/i><span style=\"font-weight: 400\">) had an advantage by covering ground more easily in a more open environment compared to their non-bipedal evolutionary cousins. There is also a growing body of evidence, including the famous \u201cLucy\u201d <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossil<\/a> of an Australopithecine, that our early ancestors lived in trees<\/span><span style=\"font-weight: 400\">. Arboreal animals usually demand a high intelligence to navigate through a three-dimensional world. It is from this lineage that humans evolved, using endurance running as a means to acquire more resources and possibly even hunt<\/span><span style=\"font-weight: 400\">. This can explain many uniquely human features, from our long legs, strong achilles, lack of lower gut protection, and our wide range of running efficiencies. <\/span><\/p>\n<figure id=\"attachment_3343\" aria-describedby=\"caption-attachment-3343\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Spreading_homo_sapiens.png\"><img decoding=\"async\" class=\"wp-image-596 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3343\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Spreading_homo_sapiens-300&#215;141.png\u00a0\u00bb alt=\u00a0\u00bbThey started in Africa and migrated toward Asia and beyond.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb141&Prime;&gt; The hypothesized movement of the homo genus. Years are marked as to the best guess of the timing of movement.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Now that the hands are freed up, the next big step is a large brain. There have been arguments from a switch to more meat eating<\/span><span style=\"font-weight: 400\">, cooking with fire<\/span><span style=\"font-weight: 400\">, tool use<\/span><span style=\"font-weight: 400\">, and even the construct of society itself<\/span><span style=\"font-weight: 400\"> to explain this increase in brain size. Regardless of how, it was this increased cognitive power that allowed humans to reign as their ancestors moved out of Africa and explored the world, ultimately entering the Americas through land bridges like the Bering Land Bridge<\/span><span style=\"font-weight: 400\">. The details of this worldwide migration and the different branches of the hominid evolutionary tree are very complex, and best reserved for its own\u00a0course.<\/span><\/p>\n<h4><span style=\"font-weight: 400\">Anthropocene and Extinction<\/span><\/h4>\n<figure id=\"attachment_3344\" aria-describedby=\"caption-attachment-3344\" style=\"width: 293px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/8.8_Extinctions_Africa_Austrailia_NAmerica_Madagascar.gif\"><img decoding=\"async\" class=\"wp-image-597 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3344\" class=\"wp-caption-text\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8_Extinctions_Africa_Austrailia_NAmerica_Madagascar-293&#215;300.gif\u00a0\u00bb alt=\u00a0\u00bbThe mammals generally decrease after humans come.\u00a0\u00bb width=\u00a0\u00bb293&Prime; height=\u00a0\u00bb300&Prime;&gt; Graph showing abundance of large mammals and the introduction of humans.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Humans have had an influence on the Earth, its ecosystems and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a>. Yet, human activity can not explain all of the changes that have occurred in the recent past. The start of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_491\">Quaternary<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>, the last and current <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a>, is marked by the start of our current <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">ice age<\/a> 2.58 million years ago<\/span><span style=\"font-weight: 400\">. During this time <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1519\">ice sheets<\/a> advanced and retreated, most likely due to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_748\">Milankovitch cycles<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/15-global-climate-change\/\">ch. 15<\/a>). Also at this time, various cold-adapted megafauna emerged (like giant sloths, saber-tooth cats, and woolly mammoths), and most of them went <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinct<\/a> as the Earth warmed from the most recent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1988\">glacial<\/a> maximum. A long-standing debate is over the cause of these and other extinctions. Is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_757\">climate<\/a> warming to blame, or were they caused by humans<\/span><span style=\"font-weight: 400\">? Certainly, we know of recent human extinctions of animals like the dodo or passenger pigeon. Can we connect modern extinctions to extinctions in the recent past? If so, there are several ideas as to how this happened. Possibly the most widely accepted and oldest is the hunting\/overkill <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a><\/span><span style=\"font-weight: 400\">. The idea behind this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a> is that humans hunted large herbivores for food, then carnivores could not find food, and human arrival times in locations has been shown to be tied to increased <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> rates in many cases.<\/span><\/p>\n<figure id=\"attachment_3345\" aria-describedby=\"caption-attachment-3345\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bingham_Canyon_mine_2016.jpg\"><img decoding=\"async\" class=\"wp-image-598 size-medium\" src=\"src\" alt=\"image\" \/><figcaption id=\"caption-attachment-3345\" class=\"wp-caption-text\">CC BY 2.0<\/a>], <a href=\"denied:&quot;https:\/\/commons.wikimedia.org\/wiki\/File%3ABingham_Canyon_mine_2016.jpg&quot;\">via Wikimedia Commons<\/a>\u00a0\u00bb src=\u00a0\u00bbhttps:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bingham_Canyon_mine_2016-300&#215;180.jpg\u00a0\u00bb alt=\u00a0\u00bbThe image is a large hole in a mountainside.\u00a0\u00bb width=\u00a0\u00bb300&Prime; height=\u00a0\u00bb180&Prime;&gt; Bingham Canyon Mine, Utah. This open pit mine is the largest man-made removal of rock in the world.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Modern human impact on the environment and the Earth as a whole is unquestioned. In fact, many scientists are starting to suggest that the rise of human civilization ended and\/or replaced the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_490\">Holocene<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1245\">epoch<\/a> and defines a new geologic time interval: the <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_489\">Anthropocene<\/a><\/b><span style=\"font-weight: 400\">. Evidence for this change includes extinctions, increased tritium (hydrogen with two neutrons) due to nuclear testing, rising pollutants like carbon dioxide, more than 200 never-before seen <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> species that have occurred only in this <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1245\">epoch<\/a><\/span><span style=\"font-weight: 400\">, materials such as plastic and metals which will be\u00a0long lasting \u00ab\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>\u00a0\u00bb in the geologic record, and large amounts of earthen material moved<\/span><span style=\"font-weight: 400\">. The biggest scientific debate with this topic is the starting point. Some say that humans\u2019 invention of agriculture would be recognized in geologic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1935\">strata<\/a> and that should be the starting point, around 12,000 years ago<\/span><span style=\"font-weight: 400\">. Others link the start of the industrial revolution and the subsequent addition of vast amounts of carbon dioxide in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a><\/span><span style=\"font-weight: 400\">. Either way, the idea is that alien geologists visiting Earth in the distant future would easily recognize the impact of humans on the Earth as the beginning of a new geologic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1244\">period<\/a>.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-55\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-55\" class=\"h5p-iframe\" data-content-id=\"55\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"8.8 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4249\" aria-describedby=\"caption-attachment-4249\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/8.8-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-599\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/8.8-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4249\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 8.8 via this QR Code.<\/figcaption><\/figure>\n<h2>Summary<\/h2>\n<p>The changes that have occurred since the inception of Earth are vast and significant. From the oxygenation of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1745\">atmosphere<\/a>, the progression of life forms, the assembly and deconstruction of several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1701\">supercontinents<\/a>, to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a> of more life forms than exist today, having a general understanding of these changes can put present change into a more rounded perspective.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-56\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-56\" class=\"h5p-iframe\" data-content-id=\"56\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 8 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4250\" aria-describedby=\"caption-attachment-4250\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/01\/Ch.8-Review-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-600\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.8-Review-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4250\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 8 via this QR Code.<\/figcaption><\/figure>\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Alvarez, L.W., Alvarez, W., Asaro, F., and Michel, H.V., 1980, Extraterrestrial cause for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_487\">cretaceous<\/a>-tertiary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a>: Science, v. 208, no. 4448, p. 1095\u20131108.<\/li>\n<li class=\"csl-entry\">Beerling, D., 2008, The emerald planet: how plants changed Earth\u2019s history: OUP Oxford.<\/li>\n<li class=\"csl-entry\">Boyce, J.W., Liu, Y., Rossman, G.R., Guan, Y., Eiler, J.M., Stolper, E.M., and Taylor, L.A., 2010, Lunar apatite with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> volatile abundances: Nature, v. 466, no. 7305, p. 466\u2013469.<\/li>\n<li class=\"csl-entry\">Brueckner, H.K., and Snyder, W.S., 1985, Structure of the Havallah sequence, Golconda allochthon, Nevada: Evidence for prolonged evolution in an accretionary prism: Geol. Soc. Am. Bull., v. 96, no. 9, p. 1113\u20131130.<\/li>\n<li class=\"csl-entry\">Brusatte, S.L., Benton, M.J., Ruta, M., and Lloyd, G.T., 2008, The first 50 Myr of dinosaur evolution: macroevolutionary pattern and morphological disparity: Biol. Lett., v. 4, no. 6, p. 733\u2013736.<\/li>\n<li class=\"csl-entry\">Canup, R.M., and Asphaug, E., 2001, Origin of the Moon in a giant impact near the end of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a>: Nature, v. 412, no. 6848, p. 708\u2013712.<\/li>\n<li class=\"csl-entry\">Clack, J.A., 2009, The Fish\u2013Tetrapod Transition: New <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">Fossils<\/a> and Interpretations: Evolution: Education and Outreach, v. 2, no. 2, p. 213\u2013223., doi: <a href=\"https:\/\/doi.org\/10\/cz257q\">10\/cz257q<\/a>.<\/li>\n<li class=\"csl-entry\">Cohen, K.M., Finney, S.C., Gibbard, P.L., and Fan, J.-X., 2013, The ICS International Chronostratigraphic Chart: Episodes, v. 36, no. 3, p. 199\u2013204.<\/li>\n<li class=\"csl-entry\">Colbert, E.H., and Morales, M.A., 1991, History of the Backboned Animals Through Time: New York: Wiley.<\/li>\n<li class=\"csl-entry\">De Laubenfels, M.W., 1956, Dinosaur <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_755\">extinction<\/a>: one more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1730\">hypothesis<\/a>: J. Paleontol.<\/li>\n<li class=\"csl-entry\">Gomes, R., Levison, H.F., Tsiganis, K., and Morbidelli, A., 2005, Origin of the cataclysmic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1258\">Late Heavy Bombardment<\/a> period of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">terrestrial<\/a> planets: Nature, v. 435, no. 7041, p. 466\u2013469.<\/li>\n<li class=\"csl-entry\">Hatcher, R.D., Jr, Thomas, W.A., and Viele, G.W., 1989, The Appalachian-Ouachita Orogen in the United States: Geological Society of America.<\/li>\n<li class=\"csl-entry\">Hosono, N., Karato, S., Makino, J., and Saitoh, T.R., 2019, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1980\">Terrestrial<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> ocean origin of the Moon: Nature Geoscience, p. 1., doi: <a href=\"https:\/\/doi.org\/10.1038\/s41561-019-0354-2\">10.1038\/s41561-019-0354-2<\/a>.<\/li>\n<li class=\"csl-entry\">Hsiao, E., 2004, Possibility of life on Europa:<\/li>\n<li class=\"csl-entry\">Hubble, E., 1929, A relation between distance and radial velocity among extra-galactic nebulae: Proc. Natl. Acad. Sci. U. S. A., v. 15, no. 3, p. 168\u2013173.<\/li>\n<li class=\"csl-entry\">Ingersoll, R.V., 1982, Triple-junction instability as cause for late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_492\">extension<\/a> and fragmentation of the western United States: Geology, v. 10, no. 12, p. 621\u2013624.<\/li>\n<li class=\"csl-entry\">Johnson, C.M., 1991, Large-scale <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formation<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1668\">lithosphere<\/a> modification beneath Middle to Late <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_488\">Cenozoic<\/a> calderas and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> fields, western North America: J. Geophys. Res. [Solid Earth], v. 96, no. B8, p. 13485\u201313507.<\/li>\n<li class=\"csl-entry\">Kass, M.S., 1999, Prognathodon stadtmani:(Mosasauridae) a new species from the Mancos <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1917\">Shale<\/a> (lower Campanian) of western Colorado: Vertebrate Paleontology in Utah, Utah Geological.<\/li>\n<li class=\"csl-entry\">Livaccari, R.F., 1991, Role of crustal thickening and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_492\">extensional<\/a> collapse in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a>\u00a0evolution of the Sevier-Laramide <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1663\">orogeny<\/a>, western United States: Geology, v. 19, no. 11, p. 1104\u20131107.<\/li>\n<li class=\"csl-entry\">McMenamin, M.A., and Schulte McMenamin, D.L., 1990, The Emergence of Animals: The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1276\">Cambrian<\/a> Breakthrough: Columbia University Press.<\/li>\n<li class=\"csl-entry\">Mitrovica, J.X., Beaumont, C., and Jarvis, G.T., 1989, Tilting of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> interiors by the dynamical effects of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subduction<\/a>: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">Tectonics<\/a>.<\/li>\n<li class=\"csl-entry\">R\u00fccklin, M., Donoghue, P.C.J., Johanson, Z., Trinajstic, K., Marone, F., and Stampanoni, M., 2012, Development of teeth and jaws in the earliest jawed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrates<\/a>: Nature, v. 491, no. 7426, p. 748\u2013751.<\/li>\n<li class=\"csl-entry\">Sahney, S., and Benton, M.J., 2008, Recovery from the most profound <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1275\">mass extinction<\/a> of all time: Proc. Biol. Sci., v. 275, no. 1636, p. 759\u2013765.<\/li>\n<li class=\"csl-entry\">Salaris, M., and Cassisi, S., 2005, Evolution of stars and stellar populations: John Wiley &amp; Sons.<\/li>\n<li class=\"csl-entry\">Schoch, R.R., 2012, Amphibian Evolution: The life of Early Land <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">Vertebrates<\/a>: Wiley-Blackwell.<\/li>\n<li class=\"csl-entry\">Sharp, B.J., 1958, MINERALIZATION IN THE <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_991\">INTRUSIVE<\/a> ROCKS IN LITTLE COTTONWOOD CANYON, UTAH: GSA Bulletin, v. 69, no. 11, p. 1415\u20131430., doi: <a href=\"https:\/\/doi.org\/10.1130\/0016-7606(1958)69[1415:MITIRI]2.0.CO;2\">10.1130\/0016-7606(1958)69[1415:MITIRI]2.0.CO;2<\/a>.<\/li>\n<li class=\"csl-entry\">Wiechert, U., Halliday, A.N., Lee, D.C., Snyder, G.A., Taylor, L.A., and Rumble, D., 2001, Oxygen <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">isotopes<\/a> and the moon-forming giant impact: Science, v. 294, no. 5541, p. 345\u2013348.<\/li>\n<li class=\"csl-entry\">Wilde, S.A., Valley, J.W., Peck, W.H., and Graham, C.M., 2001, Evidence from detrital <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1227\">zircons<\/a> for the existence of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a> and oceans on the Earth 4.4 Gyr ago: Nature, v. 409, no. 6817, p. 175\u2013178.<\/li>\n<li class=\"csl-entry\">Wood, R.A., 2019, The rise of Animals.: Scientific American, v. 320, no. 6, p. 24\u201331.<\/li>\n<\/ol>\n<\/div>\n<div class=\"media-attributions clear\" prefix:cc=\"http:\/\/creativecommons.org\/ns#\" prefix:dc=\"http:\/\/purl.org\/dc\/terms\/\"><h2>Mention de la source du contenu multim\u00e9dia<\/h2><ul><li >HubbleDeepField       <\/li><li >Example of Doppler Shift Youtube QR Code       <\/li><li >Crab_Nebula       <\/li><li >blackhole_NASA_2019       <\/li><li >8.1 Did I Get It QR Code       <\/li><li >HL_Tau_protoplanetary_disk       <\/li><li >Artist\u2019s impression of the water snowline around the young sta       <\/li><li >8.2 Did I Get It QR Code       <\/li><li >NASA Evolution of the Moon Youtube QR Code       <\/li><li >Comet_on_7_July_2015_NavCam       <\/li><li >8.3 Did I Get It QR Code       <\/li><li >Archean       <\/li><li >Pluto-in-true-color_2x_JPEG-edit-frame       <\/li><li >Lhborbits       <\/li><li >Earth cutaway schematic-en       <\/li><li >greenhouse-gas-molecules       <\/li><li >8.4.3 Animation QR Code       <\/li><li >8.4 Did I Get It QR Code       <\/li><li >8.5 Did I Get It QR Code       <\/li><li >Trilobite_Heinrich_Harder       <\/li><li >North_america_craton_nps       <\/li><li >Opabinia       <\/li><li >Coral_Outcrop_Flynn_Reef       <\/li><li >08.6_Guadalupe_Nima2       <\/li><li >How Many Mass Extinctions Youtube QR Code       <\/li><li >8.7 Video QR Code       <\/li><li >Pangea_animation_03       <\/li><li >Cretaceous_seaway       <\/li><li >Extinction_intensity.svg       <\/li><li >8.7 Did I Get It QR Code       <\/li><li >Hominidae_chart.svg       <\/li><li >8.8 Did I Get It QR Code       <\/li><li >Ch.8 Review QR Code       <\/li><\/ul><\/div><div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">d\u00e9finition<\/span><template id=\"term_601_1733\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1733\"><div tabindex=\"-1\"><p>Large surface mine with opening carved into the ground.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1778\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1778\"><div tabindex=\"-1\"><p>[glossary]<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1253\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1253\"><div tabindex=\"-1\"><p>A very fine grained version of silica deposited with or without microfossils.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1255\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1255\"><div tabindex=\"-1\"><p>A chemical or biochemical rock made of mainly calcite.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1257\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1257\"><div tabindex=\"-1\"><p>Limestone made of primarily fine-grained calcite mud. Microscopic fossils are commonly present.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1242\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1242\"><div tabindex=\"-1\"><p>Extremely thin bedding in mudstones, a characteristic of shale.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1745\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1745\"><div tabindex=\"-1\"><p>Rocks which allow petroleum resources to collect or move.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1654\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1654\"><div tabindex=\"-1\"><p>Rock with abraded surfaces formed in deserts.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1261\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1261\"><div tabindex=\"-1\"><p>Discernible layers of rock, typically from a sedimentary rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1271\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1271\"><div tabindex=\"-1\"><p>Subtle ridges formed in the upper flow regime on top of plane beds in the direction of flow.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_755\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_755\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1701\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1701\"><div tabindex=\"-1\"><p>Lake that fills a glacial valley.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2444\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2444\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_479\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_479\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_488\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_488\"><div tabindex=\"-1\"><p>By Krishnavedala (Own work) [<a href=\"http:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">CC0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AHalf_times.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2158\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2158\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1243\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1243\"><div tabindex=\"-1\"><p>A very fine-grained rock with very thin layering (fissile).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1667\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1667\"><div tabindex=\"-1\"><p>The process that turns non-desert land into desert.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1719\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1719\"><div tabindex=\"-1\"><p>The ability for the atmosphere to absorb heat that is emitted by a planet's surface.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2264\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2264\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1720\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1720\"><div tabindex=\"-1\"><p>Climate changed caused by human activity, namely, the burning of fossil fuels.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1721\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1721\"><div tabindex=\"-1\"><p>Having to do with humans.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1247\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1247\"><div tabindex=\"-1\"><p>An evaporite mineral, CaSo4\u20222H2O. Has one cleavage, hardness of 2. Typically clear or white.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1729\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1729\"><div tabindex=\"-1\"><p>Valuable material in the Earth, typically used for metallic mineral resources.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1248\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1248\"><div tabindex=\"-1\"><p>Also known as rock salt, or table salt. 3 cleavages at 90\u00b0, cubic crystal habit. Typically clear or white, hardness of 3.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1246\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1246\"><div tabindex=\"-1\"><p>A chemical sedimentary rock that forms as water evaporates.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1249\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1249\"><div tabindex=\"-1\"><p>Spheres of calcite that form in saline waters with slight wave agitation. Ooid refers to the sphere, oolite the rock with the spheres.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2411\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2411\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1250\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1250\"><div tabindex=\"-1\"><p>Porous variety of carbonate that form in relatively unheated water, sometimes as towers and spires.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1767\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1767\"><div tabindex=\"-1\"><p>Sedimentary rocks made of mineral grains weathered as mechanical detritus of previous rocks, e.g. sand, gravel, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_985\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_985\"><div tabindex=\"-1\"><p>The thin, outer layer of the Earth which makes up the rocky bottom of the ocean basins. It is made of rocks similar to basalt, and as it cools, even become more dense than the upper mantle below.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1251\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1251\"><div tabindex=\"-1\"><p>Porous, concentric, or layered variety of carbonate that forms with often heated water in springs and\/or caves.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1252\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1252\"><div tabindex=\"-1\"><p>A sedimentary rock that formed long ago as free oxygen changed the solubility of iron, causing layers of iron rich and iron-poor sediments to form in thin layers, or bands.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1787\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1787\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1765\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1765\"><div tabindex=\"-1\"><p>A rule that says the outer valence shell of electrons is complete when it contains 8 electrons.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1909\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1909\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1254\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1254\"><div tabindex=\"-1\"><p>Chemical sedimentary rocks that have a biologic component to their origin. Many limestones are biochemical.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1664\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1664\"><div tabindex=\"-1\"><p>Dunes that form semicircular shapes due to anchoring vegetation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1658\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1658\"><div tabindex=\"-1\"><p>Dangerous flooding that occurs in arid regions.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1228\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1228\"><div tabindex=\"-1\"><p>Lowest layer of the soil (C), which is mechanically weathered (not chemically weathered) bedrock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_228\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_228\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_493\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_493\"><div tabindex=\"-1\"><p>By Zkeizars (Own work) [<a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a> or <a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/4.0-3.0-2.5-2.0-1.0\">CC BY-SA 4.0-3.0-2.5-2.0-1.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AKeizars_TLexplained2.jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2044\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2044\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1751\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1751\"><div tabindex=\"-1\"><p>Metallic mineral deposit consisting of mafic plutonic rocks, typically containing platinum-group elements, chromium, copper, nickel, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_221\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_221\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1750\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1750\"><div tabindex=\"-1\"><p>Minerals that have a luster that is not similar to metal, and typically do not contain valuable metals like copper, lead, zinc, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1659\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1659\"><div tabindex=\"-1\"><p>Planar flow of water over land surfaces.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1008\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1008\"><div tabindex=\"-1\"><p>Mix of sediments that form as a subducting plate descends and the overriding plate scrapes material and material is added.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2038\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2038\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1653\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1653\"><div tabindex=\"-1\"><p>Erosional rock face caused by sand abrasion.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1006\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1006\"><div tabindex=\"-1\"><p>A process where an oceanic plate descends bellow a less dense plate, causing the removal of the plate from the surface. Subduction causes the largest earthquakes possible, as the subducting plate can lock as it goes down. Volcanism is also caused as the plate releases volatiles into the mantle, causing melting.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1009\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1009\"><div tabindex=\"-1\"><p>Name given to the subducting plate, where volatiles are driven out at depth, causing volcanism.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1730\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1730\"><div tabindex=\"-1\"><p>Potentially extractible and valuable material, but unproven.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1779\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1779\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1244\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1244\"><div tabindex=\"-1\"><p>A rock made of primarily silt.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1258\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1258\"><div tabindex=\"-1\"><p>Limestone made of shell fragments cemented together.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2181\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2181\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1742\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1742\"><div tabindex=\"-1\"><p>A dark liquid fossil fuel derived from petroleum.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_225\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_225\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1755\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1755\"><div tabindex=\"-1\"><p>Oxidation that occurs in sulfide deposits which can concentrate valuable elements like copper.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_226\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_226\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2423\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2423\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2165\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2165\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1669\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1669\"><div tabindex=\"-1\"><p>Glaciers that form in cool or mountainous areas.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1668\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1668\"><div tabindex=\"-1\"><p>A body of ice that moves downhill under its own mass.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1749\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1749\"><div tabindex=\"-1\"><p>Minerals with a luster similar to metal and contain metals, including valuable elements like lead, zinc, copper, tin, etc.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1718\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1718\"><div tabindex=\"-1\"><p>A system which reverts back to a baseline when it deviates.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1259\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1259\"><div tabindex=\"-1\"><p>A limestone made of&nbsp;coccolithophore shells, a type of single-celled algae.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1023\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1023\"><div tabindex=\"-1\"><p>Place where oceanic-oceanic subduction causes volcanoes to form on an overriding oceanic plate, making a chain of active volcanoes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1260\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1260\"><div tabindex=\"-1\"><p>Former swamp-derived (plant) material that is part of the rock record.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1687\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1687\"><div tabindex=\"-1\"><p>Term for a rock made definitively of glacial till.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1753\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1753\"><div tabindex=\"-1\"><p>Metallic mineral deposit which forms near mid-ocean ridges.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1968\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1968\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1227\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1227\"><div tabindex=\"-1\"><p>Lower layer of the soil (B) which is a mixture of weathered bedrock, leeched materials, and organic material. Has two sublayers: the upper part, or regolith (with more organic materials), and the lower part, saprolite, which is only slightly weathered bedrock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1999\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1999\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_234\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_234\"><div tabindex=\"-1\"><figure id=\"attachment_2752\" aria-describedby=\"caption-attachment-2752\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Cristales_cueva_de_Naica.jpg\"><img class=\"wp-image-2752 size-large\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/Cristales_cueva_de_Naica-1024x683-1.jpg\" alt=\"The crystals are huge!\" width=\"1024\" height=\"683\"><\/a><figcaption id=\"caption-attachment-2752\" class=\"wp-caption-text\">These selenite (gypsum) crystals, found in The Cave of the Crystals in Naica, Mexico, has some of the largest minerals ever found. The largest crystal found here is 39 feet (12 meters) and 55 tones.<\/figcaption><\/figure>\n<h1>3 Minerals<\/h1>\n<p><strong>KEY<\/strong><b> CONCEPTS<\/b><\/p>\n<p><b>At the end of this chapter, students should be able to:<\/b><\/p>\n<ul>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Define <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the basic structure of the atom.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Derive basic atomic information from the Periodic Table of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">Elements<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonding<\/a> related to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the main ways <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> form.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Describe the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a> and how it forms common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">List common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">sulfate<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> groups.<\/span><\/li>\n<li style=\"font-weight: 400\"><span style=\"font-weight: 400\">Identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> using physical properties and identification tables. <\/span><\/li>\n<\/ul>\n<p>The term \u201c<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>\u201d as used in nutrition labels and pharmaceutical products is not the same as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> in a geological sense. In geology, the classic definition of a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a><\/strong> is: 1) naturally occurring, 2) inorganic, 3) solid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a>, 4) regular crystal structure, and 5) defined chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a>. Some natural substances technically should not be considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, but are included by exception. For example, water and mercury are liquid at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a>. Both are considered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> because they were classified before the room-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> rule was accepted as part of the definition. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a> is quite often formed by organic processes, but is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> because it is widely found and geologically important. Because of these discrepancies, the International Mineralogical Association in 1985 amended the definition to: \u201cA <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> is an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> or chemical compound that is normally crystalline and that has been formed as a result of geological processes.\u201d This means that the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> in the shell of a clam is not considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>. But once that clam shell undergoes burial, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1905\">diagenesis<\/a>, or other geological processes, then the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> is considered a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>. Typically, substances like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1934\">coal<\/a>, pearl, opal, or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_999\">obsidian<\/a> that do not fit the definition of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> are called mineraloids.<\/p>\n<p>A <strong>rock<\/strong> is a substance that contains one or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> or mineraloids. As is discussed in later chapters, there are three types of rocks <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> (rocks crystallizing from molten material), sedimentary (rocks <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of products of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_251\">mechanical weathering<\/a> (sand, gravel, etc.) and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1890\">chemical weathering<\/a> (things <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitated<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a>), and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> (rocks produced by alteration of other rocks by heat and pressure.<\/p>\n<h2><span style=\"font-weight: 400\">3.1 Chemistry of Minerals<\/span><\/h2>\n<p>Rocks are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> that have a specific chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a>.\u00a0 To understand <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> chemistry, it is essential to examine the fundamental unit of all matter, the atom.<\/p>\n<h3><b>3.1.1 The Atom<\/b><\/h3>\n<figure id=\"attachment_2753\" aria-describedby=\"caption-attachment-2753\" style=\"width: 283px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.1-Electron_cloud_model_of_atom.jpg\"><img class=\"size-medium wp-image-2753\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/03.1-Electron_cloud_model_of_atom-283x300-1.jpg\" alt=\"Image of atom with defined nucleus and electrons surrounding it in a cloud with concentrations of electrons in energy shells\" width=\"283\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2753\" class=\"wp-caption-text\">Electron cloud model of the atom<\/figcaption><\/figure>\n<p>Matter is made of atoms. Atoms consists of subatomic particles\u2014<strong>protons<\/strong>, <strong>neutrons<\/strong>, and <strong>electrons<\/strong>. A simple model of the atom has a central nucleus <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of protons, which have positive charges, and neutrons which have no charge. A cloud of negatively charged electrons surrounds the nucleus, the number of electrons equaling the number of protons thus balancing the positive charge of the protons for a neutral atom. Protons and neutrons each have a mass number of 1. The mass of an electron is less than\u00a01\/1000<sup>th<\/sup>\u00a0that of a proton or neutron, meaning most of the atom\u2019s mass is in the nucleus.<\/p>\n<h3><b>3.1.2 Periodic Table of the Elements<\/b><\/h3>\n<p>Matter is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> which are atoms that have a specific number of protons in the nucleus. This number of protons is called the <strong>Atomic Number<\/strong> for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>. For example, an oxygen atom has 8 protons and an iron atom has 26 protons. An <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> cannot be broken down chemically into a simpler form and retains unique chemical and physical properties. Each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> behaves in a unique manner in nature. This uniqueness led scientists to develop a periodic table of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>, a tabular arrangement of all known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> listed in order of their atomic number.<\/p>\n<figure id=\"attachment_2754\" aria-describedby=\"caption-attachment-2754\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Periodic_Table-02-scaled.jpg\"><img class=\"size-large wp-image-2754\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/Periodic_Table-02-1024x795-1.jpg\" alt=\"The Periodic Table of the Elements showing all elements with their chemical symbols, atomic weight, and atomic number.\" width=\"1024\" height=\"795\"><\/a><figcaption id=\"caption-attachment-2754\" class=\"wp-caption-text\">The Periodic Table of the Elements<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The first arrangement of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> into a periodic table was done by Dmitri Mendeleev in 1869 using the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> known at the time<\/span><span style=\"font-weight: 400\">. In the periodic table, each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> has a chemical symbol, name, atomic number, and atomic mass. The chemical symbol is an abbreviation for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>, often derived from a Latin or Greek name for the substance<\/span><span style=\"font-weight: 400\">. The atomic number is the number of protons in the nucleus. The atomic mass is the number of protons and neutrons in the nucleus, each with a mass number of one. Since the mass of electrons is so much less than the protons and neutrons, the atomic mass is effectively the number of protons plus neutrons. <\/span><\/p>\n<figure id=\"attachment_2755\" aria-describedby=\"caption-attachment-2755\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3a_Formation_of_Carbon14_from_Nitrogen14.jpg\"><img class=\"size-medium wp-image-2755\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/3.3a_Formation_of_Carbon14_from_Nitrogen14-300x123-1.jpg\" alt=\"\" width=\"300\" height=\"123\"><\/a><figcaption id=\"caption-attachment-2755\" class=\"wp-caption-text\">Formation of Carbon 14 from Nitrogen 14<\/figcaption><\/figure>\n<p>The atomic mass of natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> represents an average mass of the atoms comprising that substance in nature and is usually not a whole number as seen on the periodic table, meaning that an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> exists in nature with atoms having different numbers of neutrons. The differing number of neutrons affects the mass of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> in nature and the atomic mass number represents this average. This gives rise to the concept of\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">isotope<\/a><strong>.\u00a0<\/strong><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">Isotopes<\/a> <\/strong>are forms of an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> with the same number of protons but different numbers of neutrons. There are usually several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">isotopes<\/a> for a particular <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>. For example, 98.9% of carbon atoms have 6 protons and 6 neutrons. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1779\">isotope<\/a> of carbon is called carbon-12 (<sup>12<\/sup>C). A few carbon atoms, carbon-13 (<sup>13<\/sup>C), have 6 protons and 7 neutrons. A trace amount of carbon atoms, carbon-14 (<sup>14<\/sup>C), has 6 protons and 8 neutrons.<\/p>\n<figure id=\"attachment_2756\" aria-describedby=\"caption-attachment-2756\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/elemental-composition-crust.jpg\"><img class=\"size-medium wp-image-2756\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/elemental-composition-crust-300x277-1.jpg\" alt=\"Oxygen and silicon make up 3\/4ths of the chart.\" width=\"300\" height=\"277\"><\/a><figcaption id=\"caption-attachment-2756\" class=\"wp-caption-text\">Element abundance pie chart for Earth's crust by Callan Bentley.<\/figcaption><\/figure>\n<p>Among the 118 known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>, the heaviest are fleeting human creations known only in high energy particle accelerators, and they decay rapidly. The heaviest naturally occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> is uranium, atomic number 92. The eight most abundant elements in Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a> are shown in Table 1<span style=\"font-weight: 400\">. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> are found in the most common rock forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<table style=\"height: 135px\">\n<tbody>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">Element<\/a><\/b><\/td>\n<td style=\"height: 15px;width: 134.797px\"><b>Symbol<\/b><\/td>\n<td style=\"height: 15px;width: 237.703px\"><b>Abundance %<\/b><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Oxygen<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">O<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">47%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Silicon<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Si<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">28%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Aluminum<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Al<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">8%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Iron<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Fe<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">5%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Calcium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Ca<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">4%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Sodium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\"><span style=\"font-weight: 400\">Na<\/span><\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Potassium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">K<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">3%<\/span><\/td>\n<\/tr>\n<tr style=\"height: 15px\">\n<td style=\"height: 15px;width: 202.188px\"><span style=\"font-weight: 400\">Magnesium<\/span><\/td>\n<td style=\"height: 15px;width: 134.797px\">Mg<\/td>\n<td style=\"height: 15px;width: 237.703px\"><span style=\"font-weight: 400\">2%<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em style=\"font-size: 16px;font-weight: 400\">Table 1. Eight Most Abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">Elements<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">Continental Crust<\/a> % by weight (source:\u00a0<a href=\"https:\/\/pubs.usgs.gov\/circ\/1953\/0285\/report.pdf\">USGS<\/a>). All other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> are less than 1%.<\/em><\/p>\n<h3><b>3.1.3 Chemical Bonding<\/b><\/h3>\n<figure id=\"attachment_2757\" aria-describedby=\"caption-attachment-2757\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/H2O_2D_labelled.svg_.png\"><img class=\"wp-image-145 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/09\/H2O_2D_labelled.svg_-300x131.png\" alt=\"The hydrogen atoms are on one side, about 105\u00b0 apart.\" width=\"300\" height=\"131\"><\/a><figcaption id=\"caption-attachment-2757\" class=\"wp-caption-text\">A model of a water molecule, showing the bonds between the hydrogen and oxygen.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Most substances on Earth are compounds containing multiple <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. Chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonding<\/a> describes how these atoms attach with each other to form compounds, such as sodium and chlorine combining to form NaCl, common table salt. Compounds that are held together by\u00a0<\/span>chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> are called molecules. Water is a compound of hydrogen and oxygen in which two hydrogen atoms are covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with one oxygen making the water molecule. The oxygen we breathe is formed when one oxygen atom covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> with another oxygen atom to make the molecule O<sub>2<\/sub>. The subscript 2 in the chemical formula indicates the molecule contains two atoms of oxygen.<\/p>\n<p>Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are also compounds of more than one <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>. The common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> has the chemical formula CaCO<sub>3<\/sub> indicating the molecule consists of one calcium, one carbon, and three oxygen atoms.\u00a0In <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, one carbon and three oxygen atoms are held together by covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> to form a <strong>molecular ion<\/strong>, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a>, which has a negative charge. Calcium as an <strong>ion<\/strong> has a positive charge of plus two. The two oppositely charged ions attract each other and combine to form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, CaCO3. The name of the chemical compound is calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a>, where calcium is Ca and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> refers to the molecular ion CO<sub>3<\/sub><sup>-2<\/sup>.<\/p>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> has the chemical formula (Mg,Fe)<sub>2<\/sub>SiO<sub>4<\/sub>, in which one silicon and four oxygen atoms are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with two atoms of either magnesium or iron.\u00a0The comma between iron (Fe) and magnesium (Mg) indicates the two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> can occupy the same location in the crystal structure and substitute for one another.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.1 Valence and Charge<\/span><\/i><\/h4>\n<p><span style=\"font-weight: 400\">The electrons around the atom\u2019s nucleus are located in shells representing different energy levels. The outermost shell is called the <strong>valence shell<\/strong>. Electrons in the valence shell are involved in chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonding<\/a>. In 1913, Niels Bohr proposed a simple model of the atom that states atoms are more stable when their outermost shell is full<\/span><span style=\"font-weight: 400\">. Atoms of most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> thus tend to gain or lose electrons so the outermost or valence shell is full. In Bohr\u2019s model, the innermost shell can have a maximum of two electrons and the second and third shells can have a maximum of eight electrons. <\/span>When the innermost shell is the valence shell, as in the case of hydrogen and helium, it obeys the octet rule when it is full with two electrons. For <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in higher rows, the octet rule of eight electrons in the valence shell applies.<\/p>\n<figure id=\"attachment_2758\" aria-describedby=\"caption-attachment-2758\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.4_Carbon_dioxide_3D_ball.png\"><img class=\"wp-image-2758 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.4_Carbon_dioxide_3D_ball-300x213-1.png\" alt=\"Carbon dioxide molecule with a carbon ion in the center and two oxygen ions on either side, each sharing two electrons with the carbon.\" width=\"300\" height=\"213\"><\/a><figcaption id=\"caption-attachment-2758\" class=\"wp-caption-text\">The carbon dioxide molecule. Since Oxygen is -2 and Carbon is +4, the two oxygens bond to the carbon to form a neutral molecule.<\/figcaption><\/figure>\n<p>The rows in the periodic table present the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in order of atomic number and the columns organize <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> with similar characteristics, such as the same number of electrons in their valence shells. Columns are often labeled from left to right with Roman numerals I to VIII, and Arabic numerals 1 through 18. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in columns I and II have 1 and 2 electrons in their respective valence shells and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in columns VI and VII have 6 and 7 electrons in their respective valence shells.<\/p>\n<p><span style=\"font-weight: 400\">In row 3 and column I, sodium (Na) has 11 protons in the nucleus and 11 electrons in three shells\u20142 electrons in the inner shell, 8 electrons in the second shell, and 1 electron in the valence shell. To maintain a full outer shell of 8 electrons per the octet rule, sodium readily gives up that 1 electron so there are 10 total electrons. With 11 positively charged protons in the nucleus and 10 negatively charged electrons in two shells, sodium when forming chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> is an ion with an overall net charge of +1<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<p><span style=\"font-weight: 400\">All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in column I have a single electron in their valence shell and a valence of 1.\u00a0<\/span>These other column I <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> also readily give up this single valence electron and thus become ions with a +1 charge. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">Elements<\/a> in column II readily give up 2 electrons and end up as ions with a charge of +2. Note that elements in columns I and II which readily give up their valence electrons, often form bonds with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in columns VI and VII which readily take up these electrons. \u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">Elements<\/a> in columns 3 through 15 are usually involved in covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonding<\/a>. The last column 18 (VIII) contains the <strong>noble gases<\/strong>. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> are chemically inert because the valence shell is already full with 8 electrons, so they do not gain or lose electrons. An example is the noble gas helium which has 2 valence electrons in the first shell. Its valence shell is therefore full. All <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in column VIII possess full valence shells and do not form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>.<\/p>\n<p><span style=\"font-weight: 400\">As seen above, an atom with a net positive or negative charge as a result of gaining or losing electrons is called an <strong>ion<\/strong>. In general the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> on the left side of the table lose electrons and become positive ions, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a> because they are attracted to the cathode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> on the right side tend to gain electrons. These are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1782\">anions<\/a> because they are attracted to the anode in an electrical device. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> in the center of the periodic table, columns 3 through 15, do not consistently follow the octet rule. These are called transition <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. A common example is iron, which has a +2 or +3 charge depending on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1896\">oxidation<\/a> state of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>. Oxidized Fe<sup>+3<\/sup> carries a +3 charge and reduced Fe<sup>+2<\/sup> is +2. These two different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1896\">oxidation<\/a> states of iron often impart dramatic colors to rocks containing their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>\u2014the oxidized form producing red colors and the reduced form producing green.<\/span><\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.2\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Ionic Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2759\" aria-describedby=\"caption-attachment-2759\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03-Sodium-chloride-3D-ionic.png\"><img class=\"size-medium wp-image-2759\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03-Sodium-chloride-3D-ionic-300x284-1.png\" alt=\"Image of crystal model of halite with ions of sodium and chlorine arranged in a cubic structure.\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2759\" class=\"wp-caption-text\">Cubic arrangement of Na and Cl in Halite<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a>, also called electron-transfer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a>, are formed by the electrostatic attraction between atoms having opposite charges. Atoms of two opposite charges attract each other electrostatically and form an <strong>ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a><\/strong> in which the positive ion transfers its electron (or electrons) to the negative ion which takes them up. Through this transfer both atoms thus achieve a full valence shell.\u00a0<\/span>For example one atom of sodium (Na<sup>+1<\/sup>) and one atom of chlorine (Cl<sup>-1<\/sup>) form an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> to make the compound sodium chloride (NaCl). This is also known as the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> or common table salt. Another example is calcium (Ca<sup>+2<\/sup>) and chlorine (Cl<sup>-1<\/sup>) combining to make the compound calcium chloride (CaCl<sub>2<\/sub>). The subscript 2 indicates two atoms of chlorine are ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> to one atom of calcium.<\/p>\n<h4><i><span style=\"font-weight: 400\">3.1.3.3\u00a0<\/span><\/i><i><span style=\"font-weight: 400\">Covalent <\/span><\/i><i><span style=\"font-weight: 400\">Bonding<\/span><\/i><\/h4>\n<figure id=\"attachment_2760\" aria-describedby=\"caption-attachment-2760\" style=\"width: 249px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Covalent.svg_.png\"><img class=\"size-medium wp-image-2760\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Covalent.svg_-249x300-1.png\" alt=\"Each atom is sharing electrons.\" width=\"249\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2760\" class=\"wp-caption-text\">Methane molecule<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> are usually formed between a <strong>metal<\/strong> and a <strong>nonmetal<\/strong>. Another type, called a covalent or electron-sharing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a>, commonly occurs between nonmetals. Covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> share electrons between ions to complete their valence shells. For example, oxygen (atomic number 8) has 8 electrons\u20142 in the inner shell and 6 in the valence shell. Gases like oxygen often form diatomic molecules by sharing valence electrons. In the case of oxygen, two atoms attach to each other and share 2 electrons to fill their valence shells to become the common oxygen molecule we breathe (O<sub>2<\/sub>). Methane (CH<sub>4<\/sub>) is another covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> gas. The carbon atom needs 4 electrons and each hydrogen needs 1. Each hydrogen shares its electron with the carbon to form a molecule as shown in the figure.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-18\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-18\" class=\"h5p-iframe\" data-content-id=\"18\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3754\" aria-describedby=\"caption-attachment-3754\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-149\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3754\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 28px\">3.2 Formation of Minerals<\/span><\/h2>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> form when atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> together in a crystalline arrangement. Three main ways this occurs in nature are: 1) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> directly from an aqueous (water) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> change, 2) <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1752\">crystallization<\/a> from a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> with a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> change, and 3) biological <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> by the action of organisms. <\/span><\/p>\n<h3><b> 3.2.1 Precipitation from aqueous solution<\/b><\/h3>\n<figure id=\"attachment_2761\" aria-describedby=\"caption-attachment-2761\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5_Hard_Water_Calcification.jpg\"><img class=\"size-medium wp-image-2761\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.5_Hard_Water_Calcification-300x200-1.jpg\" alt=\"Encrusted calcium carbonate (lime) deposits on faucent\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2761\" class=\"wp-caption-text\">Calcium carbonate deposits from hard water<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">Solutions<\/a> consist of ions or molecules, known as solutes, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> in a medium or solvent. In nature this solvent is usually water. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> can be dissolved in water, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> or table salt, which has the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> sodium chloride, NaCl. The Na<sup>+1<\/sup> and Cl<sup>-1<\/sup> ions separate and disperse into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a>.<\/p>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">Precipitation<\/a><\/strong> is the reverse process, in which ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> come together to form solid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">Precipitation<\/a> is dependent on the concentration of ions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> and other factors such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> and pressure. The point at which a solvent cannot hold any more solute is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1784\">saturation<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">Precipitation<\/a> can occur when the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2197\">falls<\/a>, when the solute evaporates, or with changing chemical conditions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a>. An example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> in our homes is when water evaporates and leaves behind a rind of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> on faucets, shower heads, and drinking glasses.<\/p>\n<p>In nature, changes in environmental conditions may cause the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> in water to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> and grow into crystals or cement grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediment<\/a> together. In Utah, deposits of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1924\">tufa<\/a> formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>-rich springs that emerged into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_747\">ice age<\/a> Lake Bonneville. Now exposed in dry valleys, this porous <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1924\">tufa<\/a> was a natural insulation used by pioneers to build their homes with a natural protection against summer heat and winter cold. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1925\">travertine<\/a> terraces at Mammoth Hot Springs in Yellowstone Park are another example formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> at the edges of the shallow spring-fed ponds.<\/p>\n<figure id=\"attachment_2762\" aria-describedby=\"caption-attachment-2762\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.6_1200px-Bonneville_Salt_Flats.jpg\"><img class=\"size-medium wp-image-2762\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.6_1200px-Bonneville_Salt_Flats-300x197-1.jpg\" alt=\"The Bonneville Salt Flats of Utah\" width=\"300\" height=\"197\"><\/a><figcaption id=\"caption-attachment-2762\" class=\"wp-caption-text\">The Bonneville Salt Flats of Utah<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Another example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> occurs in the Great Salt Lake, Utah, where the concentration of sodium chloride and other salts is nearly eight times greater than in the world\u2019s oceans <\/span><span style=\"font-weight: 400\">[zotpressInText item=\"{DU5CMSHJ}\" format=\"%num%\" brackets=\"yes\"]<\/span><span style=\"font-weight: 400\">.\u00a0<\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2212\">Streams<\/a> carry salt ions into the lake from the surrounding mountains. With no other outlet, the water in the lake evaporates and the concentration of salt increases until <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1784\">saturation<\/a> is reached and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitate<\/a> out as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediments<\/a>. Similar salt deposits include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> and other precipitates, and occur in other lakes like Mono Lake in California and the Dead Sea.<\/p>\n<h3><b>3.2.2 Crystallization from Magma<\/b><\/h3>\n<figure id=\"attachment_2763\" aria-describedby=\"caption-attachment-2763\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.5a_Pahoehoe_toe.jpg\"><img class=\"size-medium wp-image-2763\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.5a_Pahoehoe_toe-300x188-1.jpg\" alt=\"A lava flow\" width=\"300\" height=\"188\"><\/a><figcaption id=\"caption-attachment-2763\" class=\"wp-caption-text\">Lava, magma at the earth\u2019s surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Heat is energy that causes atoms in substances to vibrate. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">Temperature<\/a> is a measure of the intensity of the vibration. If the vibrations are violent enough, chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> are broken and the crystals melt releasing the ions into the melt. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">Magma<\/a> is molten rock with freely moving ions. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> is emplaced at depth or extruded onto the surface (then called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1751\">lava<\/a>), it starts to cool and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> crystals can form.<\/p>\n<h3><b>3.2.3 Precipitation by Organisms<\/b><\/h3>\n<figure id=\"attachment_2764\" aria-describedby=\"caption-attachment-2764\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.8_Ammonite_Asteroceras.jpg\"><img class=\"size-full wp-image-2764\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.8_Ammonite_Asteroceras.jpg\" alt=\"Shell of an ammonite, an extinct cephalopod, with a spiral shell in a plane.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2764\" class=\"wp-caption-text\">Ammonite shell made of calcium carbonate<\/figcaption><\/figure>\n<p><span style=\"font-size: 1em\">Many organisms build bones, shells, and body coverings by extracting ions from water and precipitating <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> biologically. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitated<\/a> by organisms is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, or calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> (CaCO3). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a> is often <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitated<\/a> by organisms as a polymorph called aragonite. <\/span><strong style=\"font-size: 1em\">Polymorphs<\/strong><span style=\"font-size: 1em\"> are crystals with the same chemical formula but different crystal structures. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">Marine<\/a> invertebrates such as corals and clams <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitate<\/a> aragonite or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> for their shells and structures. Upon death, their hard parts accumulate on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1963\">ocean floor<\/a> as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediments<\/a>, and eventually may become the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1761\">sedimentary rock<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a>. Though <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a> can form inorganically, the vast majority is formed by this biological process. Another example is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> organisms called radiolaria, which are zooplankton that <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitate<\/a> silica for their microscopic external shells. When the organisms die, the shells accumulate on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1963\">ocean floor<\/a> and can form the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1761\">sedimentary rock<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1927\">chert<\/a>. An example of biologic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a> from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1274\">vertebrate<\/a> world is bone, which is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> mostly of a type of apatite, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">phosphate<\/a> group. The apatite found in bones contains calcium and water in its structure and is called hydroxycarbonate apatite, Ca<\/span><sub>5<\/sub><span style=\"font-size: 1em\">(PO<\/span><sub>4<\/sub><span style=\"font-size: 1em\">)<\/span><sub>3<\/sub><span style=\"font-size: 1em\">(OH).\u00a0 As mentioned above, such substances are not technically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> until the organism dies and these hard parts become <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-19\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-19\" class=\"h5p-iframe\" data-content-id=\"19\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3753\" aria-describedby=\"caption-attachment-3753\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-154\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3753\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.3 Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2765\" aria-describedby=\"caption-attachment-2765\" style=\"width: 256px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedron.gif\"><img class=\"size-full wp-image-2765\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tetrahedron.gif\" alt=\"It is a pyramid shape with a triangular base\" width=\"256\" height=\"256\"><\/a><figcaption id=\"caption-attachment-2765\" class=\"wp-caption-text\">Rotating animation of a tetrahedra<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> are categorized based on their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> and structure. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are built around a molecular ion called the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a><\/strong>. A tetrahedron has a pyramid-like shape with four sides and four corners.\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">Silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> form the largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> on Earth, comprising the vast majority of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. Of the nearly four thousand known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> on Earth, most are rare. There are only a few that make up most of the rocks likely to be encountered by surface dwelling creatures like us. These are generally called the <strong>rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a><\/strong>.<\/p>\n<figure id=\"attachment_2766\" aria-describedby=\"caption-attachment-2766\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.10_Tetrahedron.jpg\"><img class=\"size-medium wp-image-2766\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.10_Tetrahedron-300x300-1.jpg\" alt=\"Model of silicon-oxygen tetrahedron of ping pong balls with a tiny silicon ion in the space in the middle of the four large balls\" width=\"300\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2766\" class=\"wp-caption-text\">Ping pong ball model of tetrahedron: balls are oxygen, lead sinker in center is silicon<\/figcaption><\/figure>\n<p>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a> (SiO<sub>4<\/sub>) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. Each oxygen ion has a -2 charge and the silicon ion has a +4 charge. The silicon ion shares one of its four valence electrons with each of the four oxygen ions in a covalent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> to create a symmetrical geometric four-sided pyramid figure. Only half of the oxygen\u2019s valence electrons are shared, giving the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a> an ionic charge of -4. This <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a> forms bonds with many other combinations of ions to form the large group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2767\" aria-describedby=\"caption-attachment-2767\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.11_Tetrahedron_open.jpg\"><img class=\"size-medium wp-image-2767\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.11_Tetrahedron_open-300x255-1.jpg\" alt=\"Top ball removed showing the tiny silicon ion in the center\" width=\"300\" height=\"255\"><\/a><figcaption id=\"caption-attachment-2767\" class=\"wp-caption-text\">The silicon ion in the center of the tetrahedron<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The silicon ion is much smaller than the oxygen ions (see the figures) and fits into a small space in the center of the four large oxygen ions, seen if the top ball is removed (as shown in the figure to the right). <\/span><span style=\"font-weight: 400\">Because only one of the valence electrons of the corner oxygens is shared, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedron<\/a> has chemically active corners available to form <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a> or other positively charged ions such as Al<\/span><sub><span style=\"font-weight: 400\">+3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">+2,+3<\/span><\/sub><span style=\"font-weight: 400\">, Mg<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">, K<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, Na<\/span><sub><span style=\"font-weight: 400\">+1<\/span><\/sub><span style=\"font-weight: 400\">, and Ca<\/span><sub><span style=\"font-weight: 400\">+2<\/span><\/sub><span style=\"font-weight: 400\">. Depending on many factors, such as the original <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> chemistry, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica-oxygen tetrahedra<\/a> can combine with other tetrahedra in several different configurations. For example, tetrahedra can be isolated, attached in chains, sheets, or three dimensional structures. These combinations and others create the chemical structure in which positively charged ions can be inserted for unique chemical compositions forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> groups. \u00a0\u00a0<\/span><\/p>\n<h3><b>3.3.1 The dark ferromagnesian silicates<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2768\" aria-describedby=\"caption-attachment-2768\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.12_Peridot_in_basalt.jpg\"><img class=\"size-medium wp-image-2768\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.12_Peridot_in_basalt-300x225-1.jpg\" alt=\"Many small crystall of the green mineral olivine in a mass of basalt\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2768\" class=\"wp-caption-text\">Olivine crystals in basalt<\/figcaption><\/figure>\n<p><span style=\"font-size: 14pt\"><b>The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">Olivine<\/a> Family<\/b><\/span><\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">Olivine<\/a> is the primary <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> component in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a> rock such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1666\">peridotite<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1013\">basalt<\/a>. It is characteristically green when not weathered. The chemical formula is (Fe,Mg)<sub>2<\/sub>SiO<sub>4<\/sub>. As previously described, the comma between iron (Fe) and magnesium (Mg) indicates these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> occur in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a>.\u00a0<span style=\"font-weight: 400\">Not to be confused with a liquid <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> occurs when two or more <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> have similar properties and can freely substitute for each other in the same location in the crystal structure.<\/span><\/p>\n<figure id=\"attachment_2769\" aria-describedby=\"caption-attachment-2769\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.13_Atomic_structure_of_olivine_1.png\"><img class=\"size-full wp-image-2769\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.13_Atomic_structure_of_olivine_1.png\" alt=\"Tetrahedral structure of olivine showing the independent tetrahedra connected together by anions of iron and\/or magnesium.\" width=\"300\" height=\"258\"><\/a><figcaption id=\"caption-attachment-2769\" class=\"wp-caption-text\">Tetrahedral structure of olivine<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">Olivine<\/a> is referred to as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> family because of the ability of iron and magnesium to substitute for each other. Iron and magnesium in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> family indicates a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> forming a compositional series within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> group which can form crystals of all iron as one end member and all mixtures of iron and magnesium in between to all magnesium at the other end member. Different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> names are applied to compositions between these end members.\u00a0 In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, the iron and magnesium ions in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> are about the same size and charge, so either atom can fit into the same location in the growing crystals. Within the cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> crystals continue to grow until they solidify into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous rock<\/a>. The relative amounts of iron and magnesium in the parent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> determine which <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> in the series form. Other rarer <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> with similar properties to iron or magnesium, like manganese (Mn), can substitute into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> crystalline structure in small amounts. Such ionic substitutions in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> crystals give rise to the great variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and are often responsible for differences in color and other properties within a group or family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">Olivine<\/a> has a pure iron end-member (called fayalite) and a pure magnesium end-member (called forsterite). Chemically, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> is mostly silica, iron, and magnesium and therefore is grouped among the dark-colored <\/span>ferromagnesian<span style=\"font-weight: 400\"> (iron=ferro, magnesium=magnesian) or <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a><\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, a contraction of their chemical symbols Ma and Fe. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">Mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are also referred to as dark-colored ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <em>Ferro<\/em> means iron and <em>magnesian<\/em> refers to magnesium. Ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> tend to be more dense than non-ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a>. This difference in density ends up being important in controlling the behavior of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> rocks that are built from these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>: whether a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1680\">subducts<\/a> or not is largely governed by the density of its rocks, which are in turn controlled by the density of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> that comprise them.<\/span><\/p>\n<p>The crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> is built from independent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals <\/a>with independent tetrahedral structures are called neosilicates (or orthosilicates). In addition to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a>, other common neosilicate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> include garnet, topaz, kyanite, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1227\">zircon<\/a>.<\/p>\n<p>Two other similar arrangements of tetrahedra are close in structure to the neosilicates and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2016\">grade<\/a> toward the next group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, the pyroxenes. In a variation on independent tetrahedra called sorosilicates, there are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> that share one oxygen between two tetrahedra, and include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> like pistachio-green epidote, a gemstone. Another variation are the cyclosilicates, which as the name suggests, consist of tetrahedral rings, and include gemstones such as beryl, emerald, aquamarine, and tourmaline<\/p>\n<h3><b>3.3.2 Pyroxene Family<\/b><\/h3>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"300\" height=\"231\"><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2771\" aria-describedby=\"caption-attachment-2771\" style=\"width: 70px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Pyroxen-chain.png\"><img class=\"wp-image-2771\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.15_Pyroxen-chain.png\" alt=\"Single chain of tetrahedra in pyroxene, alternating with adjacent corner oxygens bonded. The outer corners are active to bond with other anions.\" width=\"70\" height=\"517\"><\/a><figcaption id=\"caption-attachment-2771\" class=\"wp-caption-text\">Single chain tetrahedral structure in pyroxene<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">Pyroxene<\/a> is another family of dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, typically black or dark green in color. Members of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a> family have a complex chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> that includes iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> to polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a>. <strong>Polymers<\/strong> are chains, sheets, or three-dimensional structures, and are formed by multiple tetrahedra covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> via their corner oxygen atoms. Pyroxenes are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> rocks such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1666\">peridotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1013\">basalt<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1016\">gabbro<\/a>, as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> rocks like eclogite and blue <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2007\">schist<\/a>.<\/p>\n<p>Pyroxenes are built from long, single chains of polymerized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a> in which tetrahedra share two corner oxygens. The silica chains are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> together into the crystal structures by metal cations. A common member of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a> family is augite, itself containing several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> series with a complex chemical formula (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)<sub>2<\/sub>O<sub>6<\/sub> that gives rise to a number of individual <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> names.<\/p>\n<p>This single-chain crystalline structure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> with many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>, which can also freely substitute for each other. The generalized chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a> is XZ(Al,Si)<sub>2<\/sub>O<sub>6<\/sub>. X represents the ions Na, Ca, Mg, or Fe, and Z represents Mg, Fe, or Al. These ions have similar ionic sizes, which allows many possible substitutions among them. Although the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a> may freely substitute for each other in the crystal, they carry different ionic charges that must be balanced out in the final crystalline structure. For example Na has a charge of +1, but Ca has charge of +2. If a Na<sup>+<\/sup> ion substitutes for a Ca<sup>+2<\/sup> ion, it creates an unequal charge that must be balanced by other ionic substitutions elsewhere in the crystal. Note that ionic size is more important than ionic charge for substitutions to occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> series in crystals.<\/p>\n<h3><\/h3>\n<h3><b>3.3.3 Amphibole Family<\/b><\/h3>\n<figure id=\"attachment_2773\" aria-describedby=\"caption-attachment-2773\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.15_Orthoclase_Hornblende.jpg\"><img class=\"wp-image-2773\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.15_Orthoclase_Hornblende-300x300-1.jpg\" alt=\"A crystal of orthoclase (potassium feldspar) wth elongated dark crystals of hornblende\" width=\"200\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2773\" class=\"wp-caption-text\">Elongated crystals of hornblende in orthoclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2772\" aria-describedby=\"caption-attachment-2772\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.16_Amphibole.jpg\"><img class=\"wp-image-2772\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.16_Amphibole-300x236-1.jpg\" alt=\"Black crystals of hornblende\" width=\"200\" height=\"157\"><\/a><figcaption id=\"caption-attachment-2772\" class=\"wp-caption-text\">Hornblende crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">Amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are built from polymerized double silica chains and they are also referred to as inosilicates. Imagine two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a> chains that connect together by sharing a third oxygen on each tetrahedra.\u00a0 Amphiboles are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> rocks and typically have a long-bladed <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a><\/strong>. The most common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a>, hornblende, is usually black; however, they come in a variety of colors depending on their chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1762\">metamorphic rock<\/a>, amphibolite, is primarily <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2774\" aria-describedby=\"caption-attachment-2774\" style=\"width: 79px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.17_Tremolite-chain.png\"><img class=\"size-medium wp-image-2774\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.17_Tremolite-chain-79x300-1.png\" alt=\"Double chain structure of amphibole; two single chains laying together with the inner corners of each tetrahedron bonded and the outer cornera active to bond with anions\" width=\"79\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2774\" class=\"wp-caption-text\">Double chain structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Amphiboles are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of iron, magnesium, aluminum, and other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a>. These dark ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are commonly found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1016\">gabbro<\/a>, baslt, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1015\">diorite<\/a>, and often form the black specks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1014\">granite<\/a>. Their chemical formula is very complex and generally written as (RSi<sub>4<\/sub>O<sub>11<\/sub>)<sub>2<\/sub>, where R represents many different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a>. For example, it can also be written more exactly as AX<sub>2<\/sub>Z<sub>5<\/sub>((Si,Al,Ti)<sub>8<\/sub>O<sub>22<\/sub>)(OH,F,Cl,O)<sub>2<\/sub>. In this formula A may be Ca, Na, K, Pb, or blank; X equals Li, Na, Mg, Fe, Mn, or Ca; and Z is Li, Na, Mg, Fe, Mn, Zn, Co, Ni, Al, \u00a0Cr, Mn, V, Ti, or Zr. The substitutions create a wide variety of colors such as green, black, colorless, white, yellow, blue, or brown. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">Amphibole<\/a> crystals can also include hydroxide ions (OH<sup>-<\/sup>)<sup>,<\/sup> which occurs from an interaction between the growing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and water <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a>.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><strong>3.3.4 Sheet Silicates<\/strong><\/h3>\n<figure id=\"attachment_2775\" aria-describedby=\"caption-attachment-2775\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany.jpg\"><img class=\"wp-image-2775\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.19_Biotite_aggregate_-_Ochtendung_Eifel_Germany-300x225-1.jpg\" alt=\"Dark brown crystals of biotite mica showing sheet-like habit\" width=\"200\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2775\" class=\"wp-caption-text\">Sheet crystals of biotite mica<\/figcaption><\/figure>\n<figure id=\"attachment_3637\" aria-describedby=\"caption-attachment-3637\" style=\"width: 250px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MicaSheetUSGOV.jpg\"><img class=\"wp-image-166\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MicaSheetUSGOV-300x226.jpg\" alt=\"Crystal of muscovite mica showing sheet structure of the mineral\" width=\"250\" height=\"188\"><\/a><figcaption id=\"caption-attachment-3637\" class=\"wp-caption-text\">Crystal of muscovite mica<\/figcaption><\/figure>\n<p>Sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> are built from tetrahedra which share all three of their bottom corner oxygens thus forming sheets of tetrahedra with their top corners available for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonding<\/a> with other atoms. Micas and clays are common types of sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a>, also known as phyllosilicates. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">Mica<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> rocks, while clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are more often found in sedimentary rocks. Two frequently found micas are dark-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">biotite<\/a>, frequently found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1014\">granite<\/a>, and light-colored <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">muscovite<\/a>, found in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1762\">metamorphic rock<\/a> called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2007\">schist<\/a>.<\/p>\n<figure id=\"attachment_2777\" aria-describedby=\"caption-attachment-2777\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.20_Silicate-sheet-3D-polyhedra.png\"><img class=\"size-medium wp-image-2777\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.20_Silicate-sheet-3D-polyhedra-300x197-1.png\" alt=\"Continuous sheets of tetradedra with all three base corners bonded to each other; the top corner active to bond with anions\" width=\"300\" height=\"197\"><\/a><figcaption id=\"caption-attachment-2777\" class=\"wp-caption-text\">Sheet structure of mica<\/figcaption><\/figure>\n<p>Chemically, sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> usually contain silicon and oxygen in a 2:5 ratio (Si<sub>4<\/sub>O<sub>10<\/sub>). Micas contain mostly silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">Biotite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica<\/a> has more iron and magnesium and is considered a ferromagnesian <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">Muscovite<\/a> micas belong to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">Felsic<\/a> is a contraction formed from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>, the dominant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> rocks.<\/p>\n<figure id=\"attachment_2778\" aria-describedby=\"caption-attachment-2778\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.21_Crystal-structure-of-mica.jpg\"><img class=\"size-medium wp-image-2778\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.21_Crystal-structure-of-mica-300x300-1.jpg\" alt=\"Diagram of mica crystal structure with the sheets of tetrahedra inverted onto each other into sandwiches with the active corners bonded with anions and the sandwiches connected together with large potassium ions that form weak bonds easily separated so the crystal comes apart into sheets.\" width=\"300\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2778\" class=\"wp-caption-text\">Crystal structure of a mica<\/figcaption><\/figure>\n<figure id=\"attachment_2779\" aria-describedby=\"caption-attachment-2779\" style=\"width: 296px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Illmenite-mica-sandwich.jpg\"><img class=\"size-medium wp-image-2779\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Illmenite-mica-sandwich-296x300-1.jpg\" alt=\"Silica sheets layered in mica like bread and hjam in a stack of sandwiches\" width=\"296\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2779\" class=\"wp-caption-text\">Mica \"silica sandwich\" structure<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>The illustration of the crystalline structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica<\/a> shows the corner O atoms <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with K, Al, Mg, Fe, and Si atoms, forming polymerized sheets of linked tetrahedra, with an octahedral layer of Fe, Mg, or Al, between them.\u00a0 The yellow potassium ions form Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> (attraction and repulsion between atoms, molecules, and surfaces) and hold the sheets together. Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> differ from\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Covalent_bond\">covalent<\/a>\u00a0and\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Ionic_bond\">ionic<\/a>\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a>, and exist here between the sandwiches, holding them together into a stack of sandwiches. The Van der Waals <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> are weak compared to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> within the sheets, allowing the sandwiches to be separated along the potassium layers. This gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica<\/a> its characteristic property of easily cleaving into sheets.<\/p>\n<figure id=\"attachment_2780\" aria-describedby=\"caption-attachment-2780\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.22_Kaolinite-structure.jpg\"><img class=\"size-medium wp-image-2780\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.22_Kaolinite-structure-300x244-1.jpg\" alt=\"Crystal structure of kaolinite, a clay mineral with sheet structure like mica except that the\" width=\"300\" height=\"244\"><\/a><figcaption id=\"caption-attachment-2780\" class=\"wp-caption-text\">Structure of kaolinite<\/figcaption><\/figure>\n<p>Clays <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> occur in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediments<\/a> formed by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1754\">weathering<\/a> of rocks and are another family of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> with a tetrahedral sheet structure. Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> form a complex family, and are an important component of many sedimentary rocks. Other sheet <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> include serpentine and chlorite, found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> rocks.<\/p>\n<p>Clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of hydrous aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a>. One type of clay, kaolinite, has a structure like an open-faced sandwich, with the bread being a single layer of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedra<\/a> and a layer of aluminum as the spread in an octahedral configuration with the top oxygens of the sheets.<\/p>\n<h3><b>3.3.5 Framework Silicates<\/b><\/h3>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">Quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> are the two most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a>. In fact, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> itself is the single most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> in the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>. There are two types of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>, one containing potassium and abundant in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> rocks of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a>, and the other with sodium and calcium abundant in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1008\">mafic<\/a> rocks of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1659\">oceanic crust<\/a>.\u00a0 Together with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a>, these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are classified as framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a>. They are built with a three-dimensional framework of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica tetrahedra<\/a> in which all four corner oxygens are shared with adjacent tetrahedra. Within these frameworks in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> are holes and spaces into which other ions like aluminum, potassium, sodium, and calcium can fit giving rise to a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> compositions and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2781\" aria-describedby=\"caption-attachment-2781\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/min-crust-pie-chart.jpg\"><img class=\"size-medium wp-image-2781\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/min-crust-pie-chart-300x290-1.jpg\" alt=\"Feldspar is 51% of the chart.\" width=\"300\" height=\"290\"><\/a><figcaption id=\"caption-attachment-2781\" class=\"wp-caption-text\">Mineral abundance pie chart in Earth's crust by Callan Bentley.<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">Feldspars<\/a> are usually found in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1014\">granite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1010\">rhyolite<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1013\">basalt<\/a> as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1992\">metamorphic<\/a> rocks and detrital sedimentary rocks. Detrital sedimentary rocks are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of mechanically weathered rock particles, like sand and gravel. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">Quartz<\/a> is especially abundant in detrital sedimentary rocks because it is very resistant to disintegration by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1754\">weathering<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> is the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> on the Earth's surface, due to its durability, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> in the Earth's <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, comprising roughly 50% of the total <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> that make up the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>.<\/p>\n<figure id=\"attachment_2782\" aria-describedby=\"caption-attachment-2782\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.24_kspar280x210-1.jpg\"><img class=\"size-medium wp-image-2782\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.24_kspar280x210-1-300x200-1.jpg\" alt=\"A group of crystals of pink potassium feldspar\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2782\" class=\"wp-caption-text\">Pink orthoclase crystals<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">Quartz<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composed<\/a> of pure silica, SiO<sub>2<\/sub>, with the tetrahedra arranged in a three dimensional framework. Impurities consisting of atoms within this framework give rise to many varieties of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> among which are gemstones like amethyst, rose <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a>, and citrine.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">Feldspars<\/a> are mostly silica with aluminum, potassium, sodium, and calcium. Orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> (KAlSi<sub>3<\/sub>O<sub>8<\/sub>), also called potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">K-spar<\/a>, is made of silica, aluminum, and potassium. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">Quartz<\/a> and orthoclase <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">felsic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1006\">Felsic<\/a> is the compositional term applied to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1753\">igneous<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and rocks that contain an abundance of silica. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> with the formula (Ca,Na)AlSi<sub>3<\/sub>O<sub>8<\/sub>, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> (Ca,Na) indicating a series of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, one end of the series with calcium CaAl<sub>2<\/sub>Si<sub>2<\/sub>O<sub>8<\/sub>, called anorthite, and the other end with sodium NaAlSi<sub>3<\/sub>O<sub>8<\/sub>, called albite.\u00a0Note how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> accommodates the substitution of Ca<sup>++<\/sup> and Na<sup>+<\/sup>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> in this solid solution series have different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> names.<\/p>\n<figure id=\"attachment_2783\" aria-describedby=\"caption-attachment-2783\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/23-feldspar-structure.gif\"><img class=\"size-medium wp-image-2783\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/23-feldspar-structure-300x271-1.gif\" alt=\"Framework structure of feldspar with all corners of tetrahedra shared with adjacent tetrahedra; there are holes in the structure in which large anions like potassium and sodium\/calcium fit\" width=\"300\" height=\"271\"><\/a><figcaption id=\"caption-attachment-2783\" class=\"wp-caption-text\">Crystal structure of feldspar<\/figcaption><\/figure>\n<p>Note that aluminum, which has a similar ionic size to silicon, can substitute for silicon inside the tetrahedra (see figure). Because potassium ions are so much larger than sodium and calcium ions, which are very similar in size, the inability of the crystal lattice to accommodate both potassium and sodium\/calcium gives rise to the two families of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>, orthoclase and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> respectively.\u00a0Framework <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> are called tectosilicates and include the alkali metal-rich feldspathoids and zeolites.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-20\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-20\" class=\"h5p-iframe\" data-content-id=\"20\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3752\" aria-describedby=\"caption-attachment-3752\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-175\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3752\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.3 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.4 Non-Silicate Minerals<\/span><\/h2>\n<figure id=\"attachment_2784\" aria-describedby=\"caption-attachment-2784\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite.jpg\"><img class=\"size-medium wp-image-2784\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hanksite-300x200-1.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2784\" class=\"wp-caption-text\">Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few minerals that is considered a carbonate and a sulfate<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The crystal structure of non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> (see table) does not contain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silica-oxygen tetrahedra<\/a>. Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are economically important and provide metallic resources such as copper, lead, and iron. They also include valuable non-metallic products such as salt, construction materials, and fertilizer.<\/p>\n<table>\n<tbody>\n<tr>\n<td><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Mineral<\/a> \u00a0Group<\/b><\/td>\n<td><b>Examples<\/b><\/td>\n<td><b>Formula<\/b><\/td>\n<td><b>Uses<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">Native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">gold, silver, copper<\/span><\/td>\n<td><span style=\"font-weight: 400\">Au, Ag, Cu<\/span><\/td>\n<td><span style=\"font-weight: 400\">Jewelry, coins, industry<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">Carbonates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, dolomite <\/span><\/td>\n<td><span style=\"font-weight: 400\">CaCO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, CaMg(CO<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><\/td>\n<td><span style=\"font-weight: 400\">Lime, Portland cement<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">Oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">hematite, magnetite, bauxite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Fe<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">, Fe<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">, a mixture of aluminum <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">Ores of iron &amp; aluminum, pigments <\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_972\">Halides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a>, sylvite<\/span><\/td>\n<td><span style=\"font-weight: 400\">NaCl, KCl<\/span><\/td>\n<td><span style=\"font-weight: 400\">Table salt, fertilizer<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">Sulfides<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">galena, chalcopyrite, cinnabar<\/span><\/td>\n<td><span style=\"font-weight: 400\">PbS, CuFeS<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">, HgS<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ores of lead, copper, mercury<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\">Sulphates<\/span><\/td>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a>, epsom salts<\/span><\/td>\n<td><span style=\"font-weight: 400\">CaSo<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b72H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O, MgSO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">\u00b77H<\/span><sub><span style=\"font-weight: 400\">2<\/span><\/sub><span style=\"font-weight: 400\">O<\/span><\/td>\n<td><span style=\"font-weight: 400\">Sheetrock, therapeutic soak<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">Phosphates<\/a><\/span><\/td>\n<td><span style=\"font-weight: 400\">apatite<\/span><\/td>\n<td><span style=\"font-weight: 400\">Ca<\/span><sub><span style=\"font-weight: 400\">5<\/span><\/sub><span style=\"font-weight: 400\">(PO<\/span><sub><span style=\"font-weight: 400\">4<\/span><\/sub><span style=\"font-weight: 400\">)<\/span><sub><span style=\"font-weight: 400\">3<\/span><\/sub><span style=\"font-weight: 400\">(F,Cl,OH) <\/span><\/td>\n<td><span style=\"font-weight: 400\">Fertilizer, teeth, bones<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><em><span style=\"font-weight: 400\">Common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\"><em>silicate<\/em><\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\"><em>mineral<\/em><\/a> groups.<\/span><\/em><\/p>\n<h3><b>3.4.1 Carbonates<\/b><\/h3>\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"size-medium wp-image-2785\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"245\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb. Note the double-refracted word \u201ccalcite\u201d in the center of the figure due to birefringence.<\/figcaption><\/figure>\n<figure id=\"attachment_2786\" aria-describedby=\"caption-attachment-2786\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.29_Limestone_etched_section_KopeFm_new.jpg\"><img class=\"wp-image-2786\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.29_Limestone_etched_section_KopeFm_new-281x300-1.jpg\" alt=\"Piece of limestone rock full of small fossils\" width=\"200\" height=\"214\"><\/a><figcaption id=\"caption-attachment-2786\" class=\"wp-caption-text\">Limestone with small fossils<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a>\u00a0(CaCO<sub>3<\/sub>) and dolomite (CaMg(CO<sub>3<\/sub>)<sub>2<\/sub>) are the two most frequently occurring <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, and usually occur in sedimentary rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a> and dolostone rocks, respectively. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> rocks, such <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> and dolomite, are formed via evaporation and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitation<\/a>. However, most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a>-rich rocks, such as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a>, are created by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1760\">lithification<\/a> of fossilized <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1961\">marine<\/a> organisms. These organisms, including those we can see and many microscopic organisms, have shells or exoskeletons consisting of calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> (CaCO<sub>3<\/sub>). When these organisms die, their remains accumulate on the floor of the water body in which they live and the soft body parts decompose and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolve<\/a> away. The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> hard parts become included in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1756\">sediments<\/a>, eventually becoming the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1761\">sedimentary rock<\/a> called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a> may contain large, easy to see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a>, most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestones<\/a> contain the remains of microscopic creatures and thus originate from biological processes.<\/p>\n<figure id=\"attachment_2787\" aria-describedby=\"caption-attachment-2787\" style=\"width: 282px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Bifringence.jpg\"><img class=\"size-medium wp-image-2787\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Bifringence-282x300-1.jpg\" alt=\"Calcite crystal polarize light into two waves that vibrate at right angles to each other and pass through the crystal in different paths.\" width=\"282\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2787\" class=\"wp-caption-text\">Bifringence in calcite crystals<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a> crystals show an interesting property called <strong>birefringence<\/strong>, meaning they polarize light into two wave components vibrating at right angles to each other. As the two light waves pass through the crystal, they travel at different velocities and are separated by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2169\">refraction<\/a> into two different travel paths. In other words, the crystal produces a double image of objects viewed through it. Because they polarize light, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> crystals are used in special petrographic microscopes for studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and rocks.<\/p>\n<p>Many non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are referred to as salts. The term <strong>salts<\/strong> used here refers to compounds made by replacing the hydrogen in natural acids. The most abundant natural acid is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1891\">carbonic acid<\/a> that forms by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a> of carbon dioxide in water. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">Carbonate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are salts built around the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> ion (CO3<sup>-2<\/sup>) where calcium and\/or magnesium replace the hydrogen in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1891\">carbonic acid<\/a> (H<sub>2<\/sub>CO<sub>3<\/sub>). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a> and a closely related polymorph aragonite are secreted by organisms to form shells and physical structures like corals. Many such creatures draw both calcium and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> bicarbonate ions (HCO<sub>3<\/sub><sup>-<\/sup>) in ocean water. As seen in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> identification section below, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> is easily <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1893\">dissolved<\/a> in acid and thus effervesces in dilute hydrochloric acid (HCl). Small dropper bottles of dilute hydrochloric acid are often carried by geologists in the field as well as used in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> identification labs.<\/p>\n<p>Other salts include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> (NaCl) in which sodium replaces the hydrogen in hydrochloric acid and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a> (Ca[SO<sub>4<\/sub>] \u2022 2 H<sub>2<\/sub>O) in which calcium replaces the hydrogen in sulfuric acid. Note that some water molecules are also included in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a> crystal. Salts are often formed by evaporation and are called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1920\">evaporite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/p>\n<figure id=\"attachment_2788\" aria-describedby=\"caption-attachment-2788\" style=\"width: 425px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.30_Crystal_structure_of_Calcite.png\"><img class=\"wp-image-2788\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.30_Crystal_structure_of_Calcite.png\" alt=\"Crystal structure of calcite showing the carbonate units of carbon surrounded by three oxygen ions and bonded to calcium ions.\" width=\"425\" height=\"520\"><\/a><figcaption id=\"caption-attachment-2788\" class=\"wp-caption-text\">Crystal structure of calcite<\/figcaption><\/figure>\n<p>The figure shows the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> (CaCO<sub>3<\/sub>). Like silicon, carbon has four valence electrons. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> unit consists of carbon atoms (tiny white dots) covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> to three oxygen atoms (red), one oxygen sharing two valence electrons with the carbon and the other two sharing one valence electron each with the carbon, thus creating triangular units with a charge of -2. The negatively charged <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> unit forms an ionic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> with the Ca ion (blue), which as a charge of +2.<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><\/h3>\n<h3><b>3.4.2 Oxides, Halides, and Sulfides<\/b><\/h3>\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"size-medium wp-image-2789\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"300\" height=\"256\"><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<p>After <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonates<\/a>, the next most common non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_972\">halides<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfides<\/a>.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">Oxides<\/a> consist of metal ions covalently <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with oxygen. The most familiar <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> is rust, which is a combination of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a> (Fe<sub>2<\/sub>O<sub>3<\/sub>) and hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a>. Hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a> form when iron is exposed to oxygen and water. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a> are important for producing metallic iron. When iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> or ore is smelted, it produces carbon dioxide (CO<sub>2<\/sub>) and metallic iron.<\/p>\n<p>The red color in rocks is usually due to the presence of iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a>. For example, the red <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1912\">sandstone<\/a> cliffs in Zion National Park and throughout Southern Utah consist of white or colorless grains of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> coated with iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> which serve as cementing agents holding the grains together.<\/p>\n<figure id=\"attachment_2790\" aria-describedby=\"caption-attachment-2790\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503.jpg\"><img class=\"wp-image-2790 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.32_Hematite_-_oolitic_with_shale_Iron_Oxide_Clinton_Oneida_County_New_York-e1512421695503-300x269-1.jpg\" alt=\"A red form of hematite called oolitic showing a mass of small round nodules\" width=\"300\" height=\"269\"><\/a><figcaption id=\"caption-attachment-2790\" class=\"wp-caption-text\">Oolitic hematite<\/figcaption><\/figure>\n<p>Other iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a> include limonite, magnetite, and hematite. Hematite occurs in many different crystal forms. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a> form shows no external structure. Botryoidal hematite shows large concentric blobs. Specular hematite looks like a mass of shiny metallic crystals. Oolitic hematite looks like a mass of dull red fish eggs. These different forms of hematite are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2018\">polymorphs<\/a> and all have the same formula, Fe<sub>2<\/sub>O<sub>3<\/sub>.<\/p>\n<p>Other common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> include:<\/p>\n<ul>\n<li>ice (H<sub>2<\/sub>O), an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> of hydrogen<\/li>\n<li>bauxite (Al<sub>2<\/sub>H<sub>2<\/sub>O<sub>4<\/sub>), hydrated <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a> of aluminum, an ore for producing metallic aluminum<\/li>\n<li>corundum (Al<sub>2<\/sub>O<sub>3<\/sub>), which includes ruby and sapphire gemstones.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2791\" aria-describedby=\"caption-attachment-2791\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.34_Halite-249324-1.jpg\"><img class=\"size-medium wp-image-2791\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.34_Halite-249324-1-300x225-1.jpg\" alt=\"Crystals of halite showing cubic crystal habit\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2791\" class=\"wp-caption-text\">Halite crystal showing cubic habit<\/figcaption><\/figure>\n<p>The <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_972\">halides<\/a><\/strong> consist of halogens in column VII, usually fluorine or chlorine, ionically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> with sodium or other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a>. These include <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> or sodium chloride (NaCl), common table salt; sylvite or potassium chloride (KCl); and fluorite or calcium fluoride (CaF<sub>2<\/sub>).<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2792\" aria-describedby=\"caption-attachment-2792\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level.jpg\"><img class=\"size-medium wp-image-2792\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.36_2014-07-05_13_04_30_View_across_the_Bonneville_Salt_Falts_Utah_from_ground_level-300x220-1.jpg\" alt=\"Photo of salt crust at the Bonneville Salt Flats in Utah with mountains in the background.\" width=\"300\" height=\"220\"><\/a><figcaption id=\"caption-attachment-2792\" class=\"wp-caption-text\">Salt crystals at the Bonneville Salt Flats<\/figcaption><\/figure>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_972\">Halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> usually form from the evaporation of sea water or other isolated bodies of water. A well-known example of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_972\">halide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> deposits created by evaporation is the Bonneville Salt Flats, located west of the Great Salt Lake in Utah (see figure).<\/p>\n<p>&nbsp;<\/p>\n<p>Many important metal ores are <b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfides<\/a>, <\/b><span style=\"font-weight: 400\">in which metals are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> to sulfur.\u00a0<\/span><span style=\"font-weight: 400\">Significant examples include: \u00a0<\/span>galena<span style=\"font-weight: 400\"> (lead <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a>), <\/span>sphalerite<span style=\"font-weight: 400\"> (zinc <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a>),<\/span> pyrite<\/p>\n<figure id=\"attachment_2794\" aria-describedby=\"caption-attachment-2794\" style=\"width: 175px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.37_pyrite1.jpg\"><img class=\"wp-image-2794\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.37_pyrite1-283x300-1.jpg\" alt=\"Cubic crystals of iron pyrite, called &quot;fools gold&quot;\" width=\"175\" height=\"185\"><\/a><figcaption id=\"caption-attachment-2794\" class=\"wp-caption-text\">Cubic crystals of pyrite<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">(<\/span><span style=\"font-weight: 400\">iron<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a>, sometimes called \u201cfool's gold\u201d), and <\/span>chalcopyrite <span style=\"font-weight: 400\">(iron-copper <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a>).<\/span><span style=\"font-weight: 400\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">Sulfides<\/a> are well known for being important ore <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. For example, galena is the main source of lead, sphalerite is the main source of zinc, and chalcopyrite is the main copper ore <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> mined in porphyry deposits like the Bingham mine (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/16-energy-and-mineral-resources\/\">chapter 16<\/a>). The largest sources of nickel, antimony, molybdenum, arsenic, and mercury are also <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfides<\/a>.<\/span><\/p>\n<h3><b>3.4.3 Sulfates<\/b><\/h3>\n<figure id=\"attachment_2795\" aria-describedby=\"caption-attachment-2795\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.39_SeleniteGypsumUSGOV.jpg\"><img class=\"size-medium wp-image-2795\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.39_SeleniteGypsumUSGOV-300x284-1.jpg\" alt=\"A clear crystal of gypsum\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2795\" class=\"wp-caption-text\">Gypsum crystal<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">Sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> contain a metal ion, such as calcium, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonded<\/a> to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">sulfate<\/a> ion. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">sulfate<\/a> ion is a combination of sulfur and oxygen (SO<sub>4<sup>-<\/sup><\/sub><sup>2<\/sup>). The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">sulfate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a> (CaSO<sub>4<\/sub>\u14272H<sub>2<\/sub>O) is used in construction materials such as plaster and drywall. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">Gypsum<\/a> is often formed from evaporating water and usually contains water molecules in its crystalline structure. The \u14272H<sub>2<\/sub>O in the formula indicates the water molecules are whole H<sub>2<\/sub>O. This is different from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a>, which contain a hydroxide ion (OH<sup>-<\/sup>) that is derived from water, but is missing a hydrogen ion (H<sup>+<\/sup>). The calcium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_974\">sulfate<\/a> without water is a different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> than <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a> called anhydrite (CaSO<sub>4<\/sub>).<\/p>\n<h3><b>3.4.4 Phosphates<\/b><\/h3>\n<figure id=\"attachment_2796\" aria-describedby=\"caption-attachment-2796\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.40_Apatite_Canada.jpg\"><img class=\"wp-image-2796\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.40_Apatite_Canada-236x300-1.jpg\" alt=\"A crystal of apatite\" width=\"150\" height=\"191\"><\/a><figcaption id=\"caption-attachment-2796\" class=\"wp-caption-text\">Apatite crystal<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">Phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> have a tetrahedral <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">phosphate<\/a> unit (PO<sub>4<\/sub><sup>-3<\/sup>) combined with various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1782\">anions<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1780\">cations<\/a>. In some cases arsenic or vanadium can substitute for phosphorus. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">Phosphates<\/a> are an important ingredient of fertilizers as well as detergents, paint, and other products. The best known <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> is apatite, Ca<sub>5<\/sub>(PO<sub>4<\/sub>)<sub>3<\/sub>(F,Cl,OH), variations of which are found in teeth and bones. The gemstone turquoise [CuAl<sub>6<\/sub>(PO<sub>4<\/sub>)<sub>4<\/sub>(OH)<sub>8<\/sub>\u00b74H2O ] is a copper-rich <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_975\">phosphate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> that, like <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a>, contains water molecules.<\/span><\/p>\n<h3><b>3.4.5 Native Element Minerals<\/b><\/h3>\n<figure id=\"attachment_2798\" aria-describedby=\"caption-attachment-2798\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.43_Sulfer_Fumarola_Vulcano.jpg\"><img class=\"wp-image-2798\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.43_Sulfer_Fumarola_Vulcano-300x225-1.jpg\" alt=\"Native sulfur deposited around the vent of a volcanic fumarole\" width=\"200\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2798\" class=\"wp-caption-text\">Native sulfur deposited around a volcanic fumarole<\/figcaption><\/figure>\n<figure id=\"attachment_2797\" aria-describedby=\"caption-attachment-2797\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.41_Native_Copper-1.jpg\"><img class=\"wp-image-2797\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.41_Native_Copper-1-300x284-1.jpg\" alt=\"Metallic native copper\" width=\"200\" height=\"189\"><\/a><figcaption id=\"caption-attachment-2797\" class=\"wp-caption-text\">Native copper<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">Native element minerals<\/a>, usually metals, occur in nature in a pure or nearly pure state. Gold is an example of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>; it is not very reactive and rarely <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> with other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> so it is usually found in an isolated or pure state. The non-metallic and poorly-reactive <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> carbon is often found as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">native<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a>, such as graphite and diamonds. Mildly reactive metals like silver, copper, platinum, mercury, and sulfur sometimes occur as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">native element minerals<\/a>. Reactive metals such as iron, lead, and aluminum almost always <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> to other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> and are rarely found in a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">native<\/a> state.<\/p>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-21\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-21\" class=\"h5p-iframe\" data-content-id=\"21\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"3.5 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3751\" aria-describedby=\"caption-attachment-3751\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-191\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3751\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.4 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">3.5 Identifying Minerals<\/span><\/h2>\n<figure id=\"attachment_2799\" aria-describedby=\"caption-attachment-2799\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Curiosity_Mars_Rover_Finds_Mineral_Match.jpg\"><img class=\"size-medium wp-image-2799\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Curiosity_Mars_Rover_Finds_Mineral_Match-300x268-1.jpg\" alt=\"The red rocks have a small hole drilled\" width=\"300\" height=\"268\"><\/a><figcaption id=\"caption-attachment-2799\" class=\"wp-caption-text\">The rover Curiosity drilled a hole in this rock from Mars, and confirmed the mineral Hematite, as mapped from satellites.<\/figcaption><\/figure>\n<p>Geologists identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> by their physical properties. In the field, where geologists may have limited access to advanced technology and powerful machines, they can still identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> by testing several physical properties: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a> and color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a>, cleavage and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a>, and some special properties. Only a few common <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> make up the majority of Earth's rocks and are usually seen as small grains in rocks. Of the several properties used for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, it is good to consider which will be most useful for identifying them in small grains surrounded by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/p>\n<h3><b>3.5.1 Luster and Color<\/b><\/h3>\n<figure id=\"attachment_2800\" aria-describedby=\"caption-attachment-2800\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Molly_Hill_molybdenite.jpg\"><img class=\"size-medium wp-image-2800\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Molly_Hill_molybdenite-300x225-1.jpg\" alt=\"The crystal looks like metal.\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2800\" class=\"wp-caption-text\">15 mm metallic hexagonal molybdenite crystal from Quebec.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The first thing to notice about a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> is its surface appearance, specifically <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a> and color. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">Luster<\/a> describes how the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> looks. Metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a> looks like a shiny metal such as chrome, steel, silver, or gold. Submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a> has a duller appearance. Pewter, for example, shows submetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a>.<\/p>\n<figure id=\"attachment_2801\" aria-describedby=\"caption-attachment-2801\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pewter-plate.jpg\"><img class=\"size-medium wp-image-2801\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pewter-plate-300x280-1.jpg\" alt=\"Antique pewter plate showing a more dull submetallic luster\" width=\"300\" height=\"280\"><\/a><figcaption id=\"caption-attachment-2801\" class=\"wp-caption-text\">Submetallic luster shown on an antique pewter plate.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>Nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a> doesn\u2019t look like a metal and may be described as vitreous (glassy), earthy, silky, pearly, and other surface qualities. Nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> may be shiny, although their vitreous shine is different from metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a>. See the table for descriptions and examples of nonmetallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a>.<\/p>\n<table style=\"width: 680px;height: 859px\">\n<tbody>\n<tr style=\"height: 32.625px\">\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">Luster<\/a><\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Image<\/span><\/th>\n<th style=\"border-color: #000000;background-color: #1ae8de;text-align: center;vertical-align: middle\"><span style=\"text-decoration: underline\">Description<\/span><\/th>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Vitreous\/glassy<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3669\" aria-describedby=\"caption-attachment-3669\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.23_-Quartz_Bresil.jpg\"><img class=\"size-thumbnail wp-image-195\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.23_-Quartz_Bresil-150x150.jpg\" alt=\"A mass of quartz crystals showing typical six sided habit with points\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3669\" class=\"wp-caption-text\">Quartz crystals<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Surface is shiny like glass<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Earthy\/dull<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2802\" aria-describedby=\"caption-attachment-2802\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.47_earthy_luster_KaolinUSGOV-1.jpg\"><img class=\"size-thumbnail wp-image-2802\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.47_earthy_luster_KaolinUSGOV-1-150x150-1.jpg\" alt=\"Specimen of kaolin, a clay oineral, showing dull or earthy luster\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2802\" class=\"wp-caption-text\">Kaolin specimen showing dull or earthy luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Dull, like dried mud or clay<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Silky<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2803\" aria-describedby=\"caption-attachment-2803\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.48_silky_luster_Selenite_Gips_Marienglas-1.jpg\"><img class=\"wp-image-2803\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.48_silky_luster_Selenite_Gips_Marienglas-1-300x230-1.jpg\" alt=\"Specimen showing silky luster\" width=\"150\" height=\"115\"><\/a><figcaption id=\"caption-attachment-2803\" class=\"wp-caption-text\">Specimen showing silky luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Soft shine like silk fabric<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Pearly<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2804\" aria-describedby=\"caption-attachment-2804\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.49_pearly_luster_Mineral_Mica_GDFL006.jpg\"><img class=\"wp-image-2804\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.49_pearly_luster_Mineral_Mica_GDFL006-300x218-1.jpg\" alt=\"Specimen showing pearly luster like the inside of a clam shell\" width=\"150\" height=\"109\"><\/a><figcaption id=\"caption-attachment-2804\" class=\"wp-caption-text\">Specimen showing pearly luster<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Like the inside of a clam shell or mother-of-pearl<\/td>\n<\/tr>\n<tr style=\"height: 28px\">\n<td style=\"width: 155px;height: 28px;text-align: center;vertical-align: middle\">Submetallic<\/td>\n<td style=\"width: 148px;height: 28px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2805\" aria-describedby=\"caption-attachment-2805\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.44_submetallic_Sphalerite4.jpg\"><img class=\"wp-image-2805\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.44_submetallic_Sphalerite4-300x277-1.jpg\" alt=\"Photo of mineral exhibiting submetallic luster\" width=\"150\" height=\"138\"><\/a><figcaption id=\"caption-attachment-2805\" class=\"wp-caption-text\">Submetallic luster on sphalerite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 333px;height: 28px;text-align: center;vertical-align: middle\">Has the appearance of dull metal,\u00a0like pewter. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> would usually still be considered metallic. Submetallic appearance can occur in metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> because of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1754\">weathering<\/a>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<figure id=\"attachment_2806\" aria-describedby=\"caption-attachment-2806\" style=\"width: 245px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Azurite_in_siltstone_Malbunka_mine_NT.jpg\"><img class=\"size-medium wp-image-2806\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Azurite_in_siltstone_Malbunka_mine_NT-245x300-1.jpg\" alt=\"There are two dark blue disks on white siltstone.\" width=\"245\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2806\" class=\"wp-caption-text\">Azurite is ALWAYS a dark blue color, and has been used for centuries for blue pigment.<\/figcaption><\/figure>\n<p>Surface color may be helpful in identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, although it can be quite variable within the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> family. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Mineral<\/a> colors are affected by the main <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> as well as impurities in the crystals. These impurities may be rare <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>\u2014like manganese, titanium, chromium, or lithium\u2014even other molecules that are not normally part of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> formula. For example, the incorporation of water molecules gives <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a>, which is normally clear, a milky color.<\/p>\n<p>Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> predominantly show a single color. Malachite and azurite are green and blue, respectively, because of their copper content. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> have a predictable range of colors due to elemental substitutions, usually via a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">Feldspars<\/a>, the most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> in the earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a>, are complex, have <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1786\">solid solution<\/a> series, and present several colors including pink, white, green, gray and others. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> also come in several colors, influenced by trace amounts of several <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. The same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">element<\/a> may show up as different colors, in different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. With notable exceptions, color is usually not a definitive property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. For identifying many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. a more reliable indicator is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a>, which is the color of the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>.<\/p>\n<h3><b>3.5.2 Streak<\/b><\/h3>\n<figure id=\"attachment_2807\" aria-describedby=\"caption-attachment-2807\" style=\"width: 450px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-scaled.jpg\"><img class=\"wp-image-2807\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.50_Streak_plate_with_Pyrite_and_Rhodochrosite-1-300x227-1.jpg\" alt=\"Pyrite showing a black streak on a white streak plate and rhodochrosite with a white streak on a black streak plate\" width=\"450\" height=\"341\"><\/a><figcaption id=\"caption-attachment-2807\" class=\"wp-caption-text\">Different minerals may have different streaks<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">Streak<\/a> examines the color of a powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>, and can be seen when a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> sample is scratched or scraped on an unglazed porcelain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>. A paper page in a field notebook may also be used for the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> of some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> that are harder than the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> will not show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a>, but will scratch the porcelain. For these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> test can be obtained by powdering the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> with a hammer and smearing the powder across a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a> or notebook paper.<\/p>\n<p>While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> surface colors and appearances may vary, their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> colors can be diagnostically useful. An example of this property is seen in the iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> hematite. Hematite occurs in a variety of forms, colors and lusters, from shiny metallic silver to earthy red-brown, and different physical appearances. A hematite <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a> is consistently reddish brown, no matter what the original specimen looks like. Iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_973\">sulfide<\/a> or pyrite, is a brassy metallic yellow. Commonly named fool\u2019s gold, pyrite has a characteristic black to greenish-black <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a>.<\/p>\n<h3><b>3.5.3 Hardness<\/b><\/h3>\n<figure id=\"attachment_2808\" aria-describedby=\"caption-attachment-2808\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.51_Mohs_Scale2.jpg\"><img class=\"size-large wp-image-2808\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.51_Mohs_Scale2-1024x714-1.jpg\" alt=\"Chart of Mohs Hardness Scale with minerals arranged in hardness from 1 to 10, also showing common items that correlate with the scale.\" width=\"1024\" height=\"714\"><\/a><figcaption id=\"caption-attachment-2808\" class=\"wp-caption-text\">Mohs Hardness Scale<\/figcaption><\/figure>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">Hardness<\/a> measures the ability of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> to scratch other substances. The Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">Hardness<\/a> Scale gives a number showing the relative scratch-resistance of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> when compared to a standardized set of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> of increasing hardness. The Mohs scale was developed by German geologist Fredrick Mohs in the early 20th century, although the idea of identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> goes back thousands of years. Mohs <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> values are determined by the strength of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>\u2019s atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a>.<\/p>\n<p>The figure shows the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> associated with specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> values, together with some common items readily available for use in field testing and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> identification. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> values run from 1 to 10, with 10 being the hardest; however, the scale is not linear. Diamond defines a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> of 10 and is actually about four times harder than corundum, which is 9. A steel pocketknife blade, which has a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a> value of 5.5, separates between hard and soft <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> on many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> identification keys.<\/p>\n<h3><b>3.5.4 Crystal Habit<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> can be identified by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a><\/strong>, how their crystals grow and appear in rocks. Crystal shapes are determined by the arrangement of the atoms within the crystal structure. For example, a cubic arrangement of atoms gives rise to a cubic-shaped <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> crystal. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">Crystal habit<\/a> refers to typically observed shapes and characteristics; however, they can be affected by other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> crystallizing in the same rock. When <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are constrained so they do not develop their typical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a>, they are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_981\">anhedral<\/a><\/strong>. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_982\">Subhedral<\/a><\/strong> crystals are partially formed shapes. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_983\">euhedral<\/a><\/strong> crystal has a perfectly formed, unconstrained shape. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> crystallize in such tiny crystals, they do not show a specific <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a> to the naked eye. Other <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, like pyrite, can have an array of different crystal habits, including cubic, dodecahedral, octahedral, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">massive<\/a>. The table lists typical crystal habits of various <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/p>\n<table style=\"width: 687px;height: 3774px\">\n<tbody>\n<tr>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">Habit<\/a><\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Image<\/span><\/strong><\/th>\n<th style=\"border-color: #000000;background-color: #6be86f;text-align: center;vertical-align: middle\" scope=\"row\"><strong><span style=\"text-decoration: underline\">Examples<\/span><\/strong><\/th>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Bladed<\/strong><\/p>\n<p>long and flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2809\" aria-describedby=\"caption-attachment-2809\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Kyanite_crystals.jpg\"><img class=\"wp-image-2809\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Kyanite_crystals-300x225-1.jpg\" alt=\"The crystals are long and rectangular\" width=\"150\" height=\"113\"><\/a><figcaption id=\"caption-attachment-2809\" class=\"wp-caption-text\">Bladed kyanite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">kyanite,\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1921\">gypsum<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Botryoidal\/mammillary<\/strong><\/p>\n<p>blobby, circular crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2810\" aria-describedby=\"caption-attachment-2810\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Malachite_Kolwezi_Katanga_Congo.jpg\"><img class=\"wp-image-2810\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Malachite_Kolwezi_Katanga_Congo-300x174-1.jpg\" alt=\"The mineral is bulbous\" width=\"150\" height=\"87\"><\/a><figcaption id=\"caption-attachment-2810\" class=\"wp-caption-text\">Malachite from the Congo<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">hematite, malachite, smithsonite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Coating\/<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1938\">laminae<\/a>\/druse<\/strong><\/p>\n<p>crystals that are small and coat surfaces<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2811\" aria-describedby=\"caption-attachment-2811\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ametyst-geode.jpg\"><img class=\"wp-image-2811\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ametyst-geode-300x200-1.jpg\" alt=\"The rock is hollowed and filled with purple minerals\" width=\"150\" height=\"100\"><\/a><figcaption id=\"caption-attachment-2811\" class=\"wp-caption-text\">Quartz (var. amethyst) geode<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, malachite, azurite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Cubic<\/strong><\/p>\n<p>cube-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2812\" aria-describedby=\"caption-attachment-2812\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.55_Cubic_Calcite-Galena-elm56c.jpg\"><img class=\"wp-image-2812\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.55_Cubic_Calcite-Galena-elm56c-260x300-1.jpg\" alt=\"Cubic crystals of galena, a sulfide of lead\" width=\"150\" height=\"173\"><\/a><figcaption id=\"caption-attachment-2812\" class=\"wp-caption-text\">Cubic crystals of galena<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite, galena, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dodecahedral<\/strong><\/p>\n<p>12-sided polygon shapes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2813\" aria-describedby=\"caption-attachment-2813\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.53_habit_dodecahedral_Pyrite_elbe-scaled.jpg\"><img class=\"wp-image-2813\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.53_habit_dodecahedral_Pyrite_elbe-300x195-1.jpg\" alt=\"Crystals of pyrite showing dodecahedral habit\" width=\"150\" height=\"97\"><\/a><figcaption id=\"caption-attachment-2813\" class=\"wp-caption-text\">Pyrite crystals with dodecahedral habit<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">garnet, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Dendritic<\/strong><\/p>\n<p>branching crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2814\" aria-describedby=\"caption-attachment-2814\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Dendrites01.jpg\"><img class=\"wp-image-2814\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Dendrites01-300x203-1.jpg\" alt=\"The mineral look like a fern. They are black and branching.\" width=\"150\" height=\"101\"><\/a><figcaption id=\"caption-attachment-2814\" class=\"wp-caption-text\">Manganese dendrites, scale in mm.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">Mn-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxides<\/a>, copper, gold<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_984\">Equant<\/a><\/strong><\/p>\n<p>crystals that do not have a long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2815\" aria-describedby=\"caption-attachment-2815\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Peridot2.jpg\"><img class=\"wp-image-209\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Peridot2-272x300.jpg\" alt=\"The crystal is light green.\" width=\"150\" height=\"165\"><\/a><figcaption id=\"caption-attachment-2815\" class=\"wp-caption-text\">Large olivine crystal<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a>, garnet, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Fibrous<\/strong><\/p>\n<p>thin, very long crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2816\" aria-describedby=\"caption-attachment-2816\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tremolite_Campolungo.jpg\"><img class=\"wp-image-2816\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tremolite_Campolungo-300x186-1.jpg\" alt=\"It is white and fiberous\" width=\"150\" height=\"93\"><\/a><figcaption id=\"caption-attachment-2816\" class=\"wp-caption-text\">Tremolite, a type of amphibole<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">serpentine, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a>, zeolite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Layered, sheets<\/strong><\/p>\n<p>stacked, very thin, flat crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2817\" aria-describedby=\"caption-attachment-2817\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.18_Muscovite-Albite-122887.jpg\"><img class=\"wp-image-2817\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.18_Muscovite-Albite-122887-300x254-1.jpg\" alt=\"Sheets of muscovite mica in crystal mass\" width=\"150\" height=\"127\"><\/a><figcaption id=\"caption-attachment-2817\" class=\"wp-caption-text\">Sheet crystals of muscovite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica <\/a>(<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">biotite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">muscovite<\/a>, etc.)<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Lenticular\/platy<\/strong><\/p>\n<p>crystals that are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1669\">plate<\/a>-like<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2818\" aria-describedby=\"caption-attachment-2818\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-Wulfenite-tcw15b.jpg\"><img class=\"wp-image-2818\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Calcite-Wulfenite-tcw15b-251x300-1.jpg\" alt=\"The orange wulfenite is bladed\" width=\"150\" height=\"179\"><\/a><figcaption id=\"caption-attachment-2818\" class=\"wp-caption-text\">Orange wulfenite on calcite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">selenite roses, wulfenite, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Hexagonal<\/strong><\/p>\n<p>crystals with six sides<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_3687\" aria-describedby=\"caption-attachment-3687\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Hanksite-1.jpg\"><img class=\"wp-image-213 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Hanksite-1-150x150.jpg\" alt=\"The mineral is hexagonal and clear.\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3687\" class=\"wp-caption-text\">Hexagonal hanksite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a>, hanksite, corundum<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_985\">Massive<\/a>\/granular<\/strong><\/p>\n<p>Crystals with no obvious shape, microscopic crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2789\" aria-describedby=\"caption-attachment-2789\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.31_Iron_oxide_LimoniteUSGOV.jpg\"><img class=\"wp-image-2789\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.31_Iron_oxide_LimoniteUSGOV-300x256-1.jpg\" alt=\"Image of limonite, a hydrated oxide of iron\" width=\"150\" height=\"128\"><\/a><figcaption id=\"caption-attachment-2789\" class=\"wp-caption-text\">Limonite, a hydrated oxide of iron<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">limonite, pyrite, azurite, bornite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Octahedral<\/strong><\/p>\n<p>4-sided double pyramid crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2819\" aria-describedby=\"caption-attachment-2819\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90.jpg\"><img class=\"wp-image-2819\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.62_octahedral_cleavage_Fluorite_crystals_rotated_90-300x182-1.jpg\" alt=\"Perfedt octahedral cleavage in fluorite generates octagon-shaped cleavage flakes.\" width=\"150\" height=\"91\"><\/a><figcaption id=\"caption-attachment-2819\" class=\"wp-caption-text\">Octagonal cleavage in fluorite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">diamond, fluorite, magnetite, pyrite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Prismatic\/columnar<\/strong><\/p>\n<p>very long, cylindrical crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2820\" aria-describedby=\"caption-attachment-2820\" style=\"width: 142px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tourmaline.jpg\"><img class=\"size-medium wp-image-2820\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tourmaline-142x300-1.jpg\" alt=\"The mineral is a long cylinder.\" width=\"142\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2820\" class=\"wp-caption-text\">Columnar tourmaline<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">tourmaline, beryl, barite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Radiating<\/strong><\/p>\n<p>crystals that grow from a point and fan out<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2821\" aria-describedby=\"caption-attachment-2821\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Pyrophyllite-236595.jpg\"><img class=\"wp-image-2821\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Pyrophyllite-236595-217x300-1.jpg\" alt=\"The mineral is orange\" width=\"150\" height=\"207\"><\/a><figcaption id=\"caption-attachment-2821\" class=\"wp-caption-text\">Pyrophyllite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">pyrite \"suns\", pyrophyllite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Rhombohedral<\/strong><\/p>\n<p>crystals shaped like slanted cubes<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2785\" aria-describedby=\"caption-attachment-2785\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.26_Calcite-rhomb.jpg\"><img class=\"wp-image-2785\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.26_Calcite-rhomb-245x300-1.jpg\" alt=\"Calcite crystal in a shape called a rhomb like a cube squahed over toward one corner\" width=\"150\" height=\"183\"><\/a><figcaption id=\"caption-attachment-2785\" class=\"wp-caption-text\">Calcite crystal in shape of rhomb.<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, dolomite<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tabular\/blocky\/stubby<\/strong><\/p>\n<p>sharp-sided crystals with no long direction<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2770\" aria-describedby=\"caption-attachment-2770\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.14_Diopside-172005.jpg\"><img class=\"wp-image-2770\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.14_Diopside-172005-300x231-1.jpg\" alt=\"Dark green crystals of diopside, a member of the pyroxene family\" width=\"150\" height=\"116\"><\/a><figcaption id=\"caption-attachment-2770\" class=\"wp-caption-text\">Crystals of diopside, a member of the pyroxene family<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a><\/td>\n<\/tr>\n<tr>\n<td style=\"width: 196px;text-align: center;vertical-align: middle\"><strong>Tetrahedral<\/strong><\/p>\n<p>three-sided, pyramid-shaped crystals<\/td>\n<td style=\"width: 133px;text-align: center;vertical-align: middle\">\n<figure id=\"attachment_2822\" aria-describedby=\"caption-attachment-2822\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tetrahedrite-Chalcopyrite-Sphalerite-251531.jpg\"><img class=\"wp-image-2822\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tetrahedrite-Chalcopyrite-Sphalerite-251531-300x218-1.jpg\" alt=\"The dark brown mineral is triangular\" width=\"150\" height=\"109\"><\/a><figcaption id=\"caption-attachment-2822\" class=\"wp-caption-text\">Tetrahedrite<\/figcaption><\/figure>\n<\/td>\n<td style=\"width: 312px;text-align: center;vertical-align: middle\">magnetite, spinel, tetrahedrite<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2824\" aria-describedby=\"caption-attachment-2824\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/GypsumStriations.jpg\"><img class=\"wp-image-2824\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/GypsumStriations-251x300-1.jpg\" alt=\"The mineral has many parallel lines on it\" width=\"150\" height=\"179\"><\/a><figcaption id=\"caption-attachment-2824\" class=\"wp-caption-text\">Gypsum with striations<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2823\" aria-describedby=\"caption-attachment-2823\" style=\"width: 150px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Staurolite-62645.jpg\"><img class=\"wp-image-2823\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Staurolite-62645-279x300-1.jpg\" alt=\"The brown minerals are replicated in different directions\" width=\"150\" height=\"161\"><\/a><figcaption id=\"caption-attachment-2823\" class=\"wp-caption-text\">Twinned staurolite<\/figcaption><\/figure>\n<p>Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a> that may be used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> is striations, which are dark and light parallel lines on a crystal face. Twinning is another, which occurs when the crystal structure replicates in mirror images along certain directions in the crystal.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"size-medium wp-image-2825\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Striations on plagioclase<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Striations and twinning are related properties in some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>. Striations are optical lines on a cleavage surface. Because of twinning in the crystal, striations show up on one of the two cleavage faces of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> crystal.<\/p>\n<h3><b>3.5.5 Cleavage and Fracture<\/b><\/h3>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> often show characteristic patterns of breaking along specific cleavage planes or show characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a> patterns. Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as reflective surfaces on the crystal, as parallel cracks that penetrate into the crystal, or show on the edge or side of the crystal as a series of steps like rice terraces. Cleavage arises in crystals where the atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> between atomic layers are weaker along some directions than others, meaning they will break preferentially along these planes.\u00a0Because they develop on atomic surfaces in the crystal, cleavage planes are optically smooth and reflect light, although the actual break on the crystal may appear jagged or uneven. In such cleavages, the cleavage surface may appear like rice terraces on a mountainside that all reflect sunlight from a particular sun angle. Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> have a strong cleavage, some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> only have weak cleavage or do not typically demonstrate cleavage.<\/p>\n<figure id=\"attachment_2826\" aria-describedby=\"caption-attachment-2826\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.57_conchoidal_Citrine-sample2.jpg\"><img class=\"size-medium wp-image-2826\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.57_conchoidal_Citrine-sample2-300x225-1.jpg\" alt=\"A specimen of a variety of quartz showing conchoidal fracture\" width=\"300\" height=\"225\"><\/a><figcaption id=\"caption-attachment-2826\" class=\"wp-caption-text\">Citrine, a variety of quartz showing conchoidal fracture<\/figcaption><\/figure>\n<p>For example, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">olivine<\/a> rarely show cleavage and typically break into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a> patterns.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2827\" aria-describedby=\"caption-attachment-2827\" style=\"width: 452px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/cryview_graphite_v1.gif\"><img class=\"wp-image-2827 size-full\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/cryview_graphite_v1.gif\" alt=\"Structure of graphite, showing single carbon layers with weak bonds holding them together\" width=\"452\" height=\"504\"><\/a><figcaption id=\"caption-attachment-2827\" class=\"wp-caption-text\">Graphite showing layers of carbon atoms separated by a gap with weak bonds holding the layers together.<\/figcaption><\/figure>\n<p>Graphite has its carbon atoms arranged into layers with relatively strong <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> within the layer and very weak <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> between the layers.\u00a0 Thus graphite cleaves readily between the layers and the layers slide easily over one another giving graphite its lubricating quality.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Mineral<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a> surfaces may be rough and uneven or they may be show <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a>. Uneven <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a> patterns are described as irregular, splintery, fibrous. A conchoidal fracture has a smooth, curved surface like a shallow bowl or conch shell, often with curved ridges. Natural <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_228\">volcanic<\/a> glass, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_999\">obsidian<\/a>, breaks with this characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_987\">conchoidal<\/a> pattern<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2828\" aria-describedby=\"caption-attachment-2828\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.64_galena_cleavage_Argentiferous_Galena-458851.jpg\"><img class=\"wp-image-2828 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.64_galena_cleavage_Argentiferous_Galena-458851-300x261-1.jpg\" alt=\"Specimen of galena showing cubic cleavage\" width=\"300\" height=\"261\"><\/a><figcaption id=\"caption-attachment-2828\" class=\"wp-caption-text\">Cubic cleavage of galena; note how the cleavage surfaces show up as different but parallel layers in the crystal.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>To work with cleavage, it is important to remember that cleavage is a result of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a> separating along planes of atoms in the crystal structure. On some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, <strong>cleavage planes<\/strong> may be confused with crystal faces. This will usually not be an issue for crystals of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> that grew together within rocks. The act of breaking the rock to expose a fresh face will most likely break the crystals along cleavage planes. Some cleavage planes are parallel with crystal faces but many are not.\u00a0Cleavage planes are smooth, flat, parallel planes within the crystal. The cleavage planes may show as parallel cracks that penetrate into the crystal (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a> below), or show on the edge or side of the crystal as a series of steps like rice terraces. For some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> characteristic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a> is to grow crystal faces even when surrounded by other crystals in rock. An example is garnet. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> grown freely where the crystals are unconstrained and can take characteristic shapes often form crystal faces (see <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">quartz<\/a> below).<\/p>\n<figure id=\"attachment_2829\" aria-describedby=\"caption-attachment-2829\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Quartz-crystals.jpg\"><img class=\"size-medium wp-image-2829\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Quartz-crystals-300x284-1.jpg\" alt=\"Freely grown quartz crystals showing crysatl faces\" width=\"300\" height=\"284\"><\/a><figcaption id=\"caption-attachment-2829\" class=\"wp-caption-text\">Freely growing quartz crystals showing crystal faces<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, distinguishing cleavage planes from crystal faces may be challenging for the student. Understanding the nature of cleavage and referring to the number of cleavage planes and cleavage angles on identification keys should provide the student with enough information to distinguish cleavages from crystal faces. Cleavage planes may show as multiple parallel cracks or flat surfaces on the crystal. Cleavage planes may be expressed as a series of steps like terraced rice paddies. See the cleavage surfaces on galena above or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> below. Cleavage planes arise from the tendency of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> crystals to break along specific planes of weakness within the crystal favored by atomic arrangements. The number of cleavage planes, the quality of the cleavage surfaces, and the angles between them are diagnostic for many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and cleavage is one of the most useful properties for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>. Learning to recognize cleavage is an especially important and useful skill in studying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>.<\/span><\/p>\n<figure id=\"attachment_2830\" aria-describedby=\"caption-attachment-2830\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.61_Cleavage_steps_in_wollastonite.jpg\"><img class=\"size-medium wp-image-2830\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.61_Cleavage_steps_in_wollastonite-300x224-1.jpg\" alt=\"Image of wollastonite, a crystal showing step-like cleavage on one side. All steps are along the same direction of cleavage.\" width=\"300\" height=\"224\"><\/a><figcaption id=\"caption-attachment-2830\" class=\"wp-caption-text\">Steps of cleavage along the same cleavage direction<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_2831\" aria-describedby=\"caption-attachment-2831\" style=\"width: 220px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.63_cleavage_in_Amphibole.jpg\"><img class=\"wp-image-2831\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.63_cleavage_in_Amphibole-295x300-1.jpg\" alt=\"Photomicrograph showing 120\/60 degree cleavage in amphibole\" width=\"220\" height=\"224\"><\/a><figcaption id=\"caption-attachment-2831\" class=\"wp-caption-text\">Photomicrograph showing 120\/60 degree cleavage within a grain of amphibole<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>As an identification property of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, cleavage is usually given in terms of the quality of the cleavage (perfect, imperfect, or none), the number of cleavage surfaces, and the angles between the surfaces.\u00a0The most common number of cleavage plane directions in the common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are: one perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica<\/a>), two cleavage planes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">pyroxene<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">amphibole<\/a>), and three cleavage planes (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>, and galena). One perfect cleavage (as in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">mica<\/a>) develops on the top and bottom of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> specimen with many parallel cracks showing on the sides but no angle of intersection. Two cleavage planes intersect at an angle. Common cleavage angles are 60\u00b0, 75\u00b0, 90\u00b0, and 120\u00b0.\u00a0 <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">Amphibole<\/a> has two cleavage planes at\u00a060\u00b0 and\u00a0120\u00b0. Galena and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> have three cleavage planes at 90\u00b0 (cubic cleavage). <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a> cleaves readily in three directions producing a cleavage figure called a rhomb that looks like a cube squashed over toward one corner giving rise to the approximately 75\u00b0 cleavage angles. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">Pyroxene<\/a> has an imperfect cleavage with two planes at 90\u00b0.<\/p>\n<p><strong>Cleavages on common rock-forming <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a><\/strong><\/p>\n<ul>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_967\">Quartz<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1789\">Olivine<\/a>\u2014none (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_987\">conchoidal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a>)<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_966\">Mica<\/a>\u20141 perfect<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">Feldspar<\/a>\u20142 perfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1790\">Pyroxene<\/a>\u20142 imperfect at 90\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1791\">Amphibole<\/a>\u20142 perfect at 60\u00b0\/120\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">Calcite<\/a>\u20143 perfect at approximately 75\u00b0<\/li>\n<li><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">Halite<\/a>, galena, pyrite\u20143 perfect at 90\u00b0<\/li>\n<\/ul>\n<h3><b>3.5.6 Special Properties <\/b><\/h3>\n<figure id=\"attachment_2832\" aria-describedby=\"caption-attachment-2832\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ulexit_Fernsehstein.jpg\"><img class=\"size-thumbnail wp-image-2832\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ulexit_Fernsehstein-150x150-1.jpg\" alt=\"The words on the page are projected upwards onto the mineral\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-2832\" class=\"wp-caption-text\">A demonstration of ulexite's image projection<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Special properties are unique and identifiable characteristics used to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> or that allow some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> to be used for special purposes.\u00a0<\/span>Ulexite has a fiber-optic property that can project images through the crystal like a high-definition television screen (see figure). A simple identifying special property is taste, such as the salty flavor of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1922\">halite<\/a> or common table salt (NaCl). Sylvite is potassium chloride (KCl) and has a more bitter taste.<\/p>\n<figure id=\"attachment_2833\" aria-describedby=\"caption-attachment-2833\" style=\"width: 225px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Latrobe_gold_nugget_Natural_History_Museum.jpg\"><img class=\"size-medium wp-image-2833\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Latrobe_gold_nugget_Natural_History_Museum-225x300-1.jpg\" alt=\"The nugget is gold\" width=\"225\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2833\" class=\"wp-caption-text\">Native gold has one of the highest specific gravities.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Another property geologists may use to identify <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> is a property related to density called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">specific gravity<\/a><\/strong>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">Specific gravity<\/a> measures the weight of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> specimen relative to the weight of an equal volume of water. The value is expressed as a ratio between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> and water weights. To measure <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">specific gravity<\/a>, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> specimen is first weighed in grams then submerged in a graduated cylinder filled with pure water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a>. The rise in water level is noted using the cylinder\u2019s graduated scale. Since the weight of water at room <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1767\">temperature<\/a> is 1 gram per cubic centimeter, the ratio of the two weight numbers gives the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">specific gravity<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">Specific gravity<\/a> is easy to measure in the laboratory but is less useful for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> identification in the field than other more easily observed properties, except in a few rare cases such as the very dense galena or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_976\">native<\/a> gold. The high density of these <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> gives rise to a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1725\">qualitative<\/a> property called \u201cheft.\u201d Experienced geologists can roughly assess <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_989\">specific gravity<\/a> by heft, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1723\">subjective<\/a> quality of how heavy the specimen feels in one\u2019s hand relative to its size.<\/p>\n<p>A simple test for identifying <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> and dolomite is to drop a bit of dilute hydrochloric acid (10-15% HCl) on the specimen. If the acid drop effervesces or fizzes on the surface of the rock, the specimen is <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a>. If it does not, the specimen is scratched to produce a small amount of powder and test with acid again. If the acid drop fizzes slowly on the powdered <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a>, the specimen is dolomite. The difference between these two <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> can be seen in the video. Geologists who work with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_969\">carbonate<\/a> rocks carry a small dropper bottle of dilute HCl in their field kit. Vinegar, which contains acetic acid, can be used for this test and is used to distinguish non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_970\">calcite<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1228\">fossils<\/a> from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1929\">limestone<\/a>. While acidic, vinegar produces less of a fizzing reaction because acetic acid is a weaker acid.<\/p>\n<figure id=\"attachment_3750\" aria-describedby=\"caption-attachment-3750\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Calcite-and-Dolomite-YouTube-QR-Code.png\"><img class=\"size-thumbnail wp-image-228\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Calcite-and-Dolomite-YouTube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3750\" class=\"wp-caption-text\">If you are using the printed version of this OER, access this YouTube video via this QR Code.<\/figcaption><\/figure>\n<figure id=\"attachment_2834\" aria-describedby=\"caption-attachment-2834\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Magnetite_Lodestone.jpg\"><img class=\"size-medium wp-image-2834\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Magnetite_Lodestone-300x200-1.jpg\" alt=\"The paperclip is sticking up into the air.\" width=\"300\" height=\"200\"><\/a><figcaption id=\"caption-attachment-2834\" class=\"wp-caption-text\">Paperclips attach to lodestone (magnetite).<\/figcaption><\/figure>\n<p>Some iron-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are magnetic and are attracted to magnets. A common name for a naturally magnetic iron <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_971\">oxide<\/a> is <strong>lodestone<\/strong>. Others include magnetite (Fe3O<sub>4<\/sub>) and ilmenite (FeTiO<sub>3<\/sub>). Magnetite is strongly attracted to magnets and can be magnetized. Ilmenite and some types of hematite are weakly magnetic.<\/p>\n<figure id=\"attachment_2825\" aria-describedby=\"caption-attachment-2825\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.65_Striations_in_plagioclase.jpg\"><img class=\"wp-image-2825 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.65_Striations_in_plagioclase-300x242-1.jpg\" alt=\"Striations or parallel dark lines on one cleavage surface on plagioclase feldspar\" width=\"300\" height=\"242\"><\/a><figcaption id=\"caption-attachment-2825\" class=\"wp-caption-text\">Iridescence on plagioclase; also showing striations on the cleavage surface<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Some <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> and mineraloids scatter light via a phenomenon called <strong>iridescence<\/strong>. This property occurs in labradorite (a variety of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a>) and opal. It is also seen in biologically created substances like pearls and seashells. Cut diamonds show iridescence and the jeweler\u2019s diamond cut is designed to maximize this property.<\/span><\/p>\n<figure id=\"attachment_2835\" aria-describedby=\"caption-attachment-2835\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD.jpg\"><img class=\"size-medium wp-image-2835\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.66_exsolution-_lamellae_perthitic_feldspar_Dan_Patch_SD-300x217-1.jpg\" alt=\"Image showing exsolution lamellae in potassium feldspar. These are separations of sodium feldspar from potassium feldspar within the crystal, not striations.\" width=\"300\" height=\"217\"><\/a><figcaption id=\"caption-attachment-2835\" class=\"wp-caption-text\">Exsolution lamellae within potassium feldspar<\/figcaption><\/figure>\n<p><strong>Striations<\/strong> on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> cleavage faces are an optical property that can be used to separate <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> from potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">K-spar<\/a>). A process called twinning creates parallel zones in the crystal that are repeating mirror images. The actual cleavage angle in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a> is slightly different than 90<sup>o<\/sup> and the alternating mirror images in these twinned zones produce a series of parallel lines on one of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">plagioclase<\/a>\u2019s two cleavage faces. Light reflects off these twinned lines at slightly different angles which then appear as light and dark lines called striations on the cleavage surface.\u00a0Potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> does not exhibit twinning or striations but may show linear features called <strong>exsolution lamellae<\/strong>, also known as perthitic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2003\">lineation<\/a> or simply perthite. Because sodium and potassium do not fit into the same <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> crystal structure, the lines are created by small amounts of sodium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> (albite) separating from the dominant potassium <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspar<\/a> (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">K-spar<\/a>) within the crystal structure. The two different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_968\">feldspars<\/a> crystallize out into roughly parallel zones within the crystal, which are seen as these linear markings.<\/p>\n<figure id=\"attachment_2793\" aria-describedby=\"caption-attachment-2793\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/03.35_FluoriteUV-scaled.jpg\"><img class=\"size-medium wp-image-2793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/03.35_FluoriteUV-244x300-1.jpg\" alt=\"Purplish crystals of fluorite. The second image shows the deep blue fluorescence of fluorite under ultraviolet light.\" width=\"244\" height=\"300\"><\/a><figcaption id=\"caption-attachment-2793\" class=\"wp-caption-text\">Fluorite. B shows fluorescence of fluorite under UV light<\/figcaption><\/figure>\n<p>One of the most interesting special <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> properties is <strong>fluorescence<\/strong>. Certain <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a>, or \u00a0trace <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a> within them, give off visible light when exposed to ultraviolet radiation or black light. Many <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">mineral<\/a> exhibits have a fluorescence room equipped with black lights so this property can be observed. An even rarer optical property is phosphorescence. <strong>Phosphorescent<\/strong> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> absorb light and then slowly release it, much like a glow-in-the-dark sticker.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><\/h3>\n<h3><\/h3>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-23\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-23\" class=\"h5p-iframe\" data-content-id=\"23\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"4.2 Schematic diagram of plutonic and volcanic structures and processes (Source: Woudloper).\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3749\" aria-describedby=\"caption-attachment-3749\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/3.5-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-231\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/3.5-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3749\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 3.5 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-size: 18pt\"><strong>Summary<\/strong><\/span><\/h2>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> are the building blocks of rocks and essential to understanding geology. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Mineral<\/a> properties are determined by their atomic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bonds<\/a>. Most <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> begin in a fluid, and either crystallize out of cooling <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1750\">magma<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1785\">precipitate<\/a> as ions and molecules out of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1784\">saturated<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1783\">solution<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> are largest group of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> on Earth, by number of varieties and relative quantity, making up a large portion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">crust<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1664\">mantle<\/a>. Based on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1788\">silicon-oxygen tetrahedra<\/a>, the crystal structure of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicates<\/a> reflects the fact that silicon and oxygen are the top two of Earth\u2019s most abundant <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1778\">elements<\/a>. Non-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1787\">silicate<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">minerals<\/a> are also economically important, and providing many types of construction and manufacturing materials. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1765\">Minerals<\/a> are identified by their unique physical properties, including <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_977\">luster<\/a>, color, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_978\">streak<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_979\">hardness<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_980\">crystal habit<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_986\">fracture<\/a>, cleavage, and special properties.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-22\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-22\" class=\"h5p-iframe\" data-content-id=\"22\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 3 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_3748\" aria-describedby=\"caption-attachment-3748\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Ch.3-Review-QR-Code.png\"><img class=\"size-thumbnail wp-image-232\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.3-Review-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a><figcaption id=\"caption-attachment-3748\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 3 via this QR Code.<\/figcaption><\/figure>\n<h2><b>References<\/b><\/h2>\n<div class=\"csl-bib-body\">\n<ol>\n<li class=\"csl-entry\">Clarke, F.W.H.S.W., 1927, The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">Composition<\/a> of the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1658\">Crust<\/a>: Professional Paper, United States Geological Survey, Professional Paper.<\/li>\n<li class=\"csl-entry\">Gordon, L.M., and Joester, D., 2011, Nanoscale chemical <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2174\">tomography<\/a> of buried organic-inorganic interfaces in the chiton tooth: Nature, v. 469, no. 7329, p. 194\u2013197.<\/li>\n<li class=\"csl-entry\">Hans Wedepohl, K., 1995, The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1909\">composition<\/a> of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1653\">continental crust<\/a>: Geochim. Cosmochim. Acta, v. 59, no. 7, p. 1217\u20131232.<\/li>\n<li class=\"csl-entry\">Lambeck, K., 1986, Planetary evolution: <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1926\">banded iron<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_2038\">formations<\/a>: v. 320, no. 6063, p. 574\u2013574.<\/li>\n<li class=\"csl-entry\">metallic <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_601_1781\">bond<\/a> | chemistry.<\/li>\n<li class=\"csl-entry\">Scerri, E.R., 2007, The Periodic Table: Its Story and Its Significance: Oxford University Press, USA.<\/li>\n<li class=\"csl-entry\">Thomson, J.J., 1897, XL. Cathode Rays: Philosophical Magazine Series 5, v. 44, no. 269, p. 293\u2013316.<\/li>\n<li class=\"csl-entry\">Trenn, T.J., Geiger, H., Marsden, E., and Rutherford, E., 1974, The Geiger-Marsden Scattering Results and Rutherford\u2019s Atom, July 1912 to July 1913: The Shifting Significance of Scientific Evidence: Isis, v. 65, no. 1, p. 74\u201382.<\/li>\n<\/ol>\n<\/div>\n<p><span style=\"font-weight: 400\">\u00a0<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1265\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1265\"><div tabindex=\"-1\"><p>A type of lamination that is cyclical, perhaps seasonal or diurnal.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1731\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1731\"><div tabindex=\"-1\"><p>A proven commodity of profitable material that could be mined.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1708\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1708\"><div tabindex=\"-1\"><p>The measure of the amount of circular or elliptical nature of the Earth's orbit.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_231\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_231\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1963\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1963\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1262\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1262\"><div tabindex=\"-1\"><p>A specific layer of rock with identifiable properties.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1783\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1783\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_971\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_971\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1927\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1927\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2009\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2009\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1785\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1785\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1935\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1935\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1893\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1893\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1784\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1784\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_747\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_747\"><div tabindex=\"-1\"><p>https:\/\/waterdata.usgs.gov\/nwis\/dv\/?ts_id=143976&amp;format=img_default&amp;site_no=404356111503901&amp;set_arithscale_y=on&amp;begin_date=19750718&amp;end_date=19890930<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2420\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2420\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_762\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_762\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1263\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1263\"><div tabindex=\"-1\"><p>The study of rock layers and their relationships to each other within a specific area.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1264\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1264\"><div tabindex=\"-1\"><p>Thin (less than 1 cm) beds of rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1269\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1269\"><div tabindex=\"-1\"><p>A specific type of sedimentary structure (ripples, plane beds, etc.) linked to a specific flow regime.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1266\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1266\"><div tabindex=\"-1\"><p>A sequence of layers in which the sediment changes linearly in size, either getting coarser or finer.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1267\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1267\"><div tabindex=\"-1\"><p>Predictable sequence of fining upward sediments, caused by turbidity flows.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2212\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2212\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_967\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_967\"><div tabindex=\"-1\"><p>By Hermann Luyken (Own work) [<a href=\"http:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/deed.en\">CC0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3A2012.10.02.111543_Bonneville_Salt_Flats_Utah.jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1912\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1912\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2013\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2013\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1268\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1268\"><div tabindex=\"-1\"><p>A qualitative measure of the speed of a fluid flow, with different amounts of flow corresponding to different sedimentary structures, called bedforms. Typically, it is split into upper and lower flow regimes, with upper being a more rapid flow.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1270\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1270\"><div tabindex=\"-1\"><p>A specific layer of rock formed by flowing fluid, either in the lowest part of the lower flow regime or lower part of the upper flow regime.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1961\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1961\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_475\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_475\"><div tabindex=\"-1\"><p>By \u05d3\u05e7\u05d9 [<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a> or <a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Disconformity.jpg\">from Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1934\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1934\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1929\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1929\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1923\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1923\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2197\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2197\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2039\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2039\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1680\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1680\"><div tabindex=\"-1\"><p>Smooth surface carved in harder rocks by glacial action.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_508\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_508\"><div tabindex=\"-1\"><p>(Source: National Park Service modified after Garber et al. 1989)<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1676\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1676\"><div tabindex=\"-1\"><p>Part of a glacier which has a net loss of material over the course of a year.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1969\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1969\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1279\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1279\"><div tabindex=\"-1\"><p>Pieces of mudcracks that are incorporated into a sedimentary rock.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1663\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1663\"><div tabindex=\"-1\"><p>Dunes that are much longer than wide, forming from wind that varies in two opposite directions.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1697\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1697\"><div tabindex=\"-1\"><p>Lake that forms in a kettle.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1698\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1698\"><div tabindex=\"-1\"><p>Ridge of sediment that forms under a glacier by meltwater which forms a river.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1695\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1695\"><div tabindex=\"-1\"><p>Large sediment (e.g. boulder) carried and then dropped by a glacier.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1670\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1670\"><div tabindex=\"-1\"><p>An alpine glacier that fills a mountain valley.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1276\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1276\"><div tabindex=\"-1\"><p>Similar to dunes, in that they are ridges of sand that form perpendicular to flow, but internally, the sediments dip up stream. Forms in the upper part of the upper flow regime.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1272\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1272\"><div tabindex=\"-1\"><p>Ridges of sediment that form perpendicular to flow in the lower part of the lower flow regime.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_757\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_757\"><div tabindex=\"-1\"><p>Photo credit to Louis J. Maher, Jr.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1988\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1988\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1917\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1917\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1273\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1273\"><div tabindex=\"-1\"><p>A large pile of sediment, deposited perpendicular to flow. Internal bedding in dunes dips toward flow direction (i.e. cross bedding). Formed in the upper part of the lower flow regime.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1776\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1776\"><div tabindex=\"-1\"><p>The measure of degrees north or south from the equator, which has a latitude of 0 degrees.&nbsp; The Earth's north and south poles have latitudes of 90 degrees north and south, respectively.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1274\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1274\"><div tabindex=\"-1\"><p>A sedimentary structure that forms in the lower flow regime, where ridges of sediment form perpendicular to flow direction, but within the ridges, sediment layers and dips toward flow direction. Found in ripples and dunes. Can be tabular, sinuous, or trough shaped.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1277\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1277\"><div tabindex=\"-1\"><p>Sedimentary layering disturbed by movement of organisms.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1976\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1976\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_970\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_970\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes. <\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1275\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1275\"><div tabindex=\"-1\"><p>A special type of cross bedding that forms when strong storms produce mounds and divots of cross-bedded sand in deeper water.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1278\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1278\"><div tabindex=\"-1\"><p>Polygonal cracking that occurs with shrinking clays. Indicative of mud submerged underwater and then exposed to air.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1980\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1980\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2194\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2194\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_476\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_476\"><div tabindex=\"-1\"><p>By \u05d3\u05e7\u05d9 [<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a> or <a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Nonconformity.jpg\">from Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_477\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_477\"><div tabindex=\"-1\"><p>By \u05d3\u05e7\u05d9 [<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a> or <a href=\"http:\/\/www.gnu.org\/copyleft\/fdl.html\">GFDL<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Angular_unconformity.jpg\">from Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_244\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_244\"><div tabindex=\"-1\"><p>By Ji-ElleIt feels nice and warmIt feels like a ________ (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3ALipari-Obsidienne_(5).jpg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_485\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_485\"><div tabindex=\"-1\"><p>By ThaLibster [<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\">CC BY-SA 4.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Decay_Chain_of_Uranium-238.svg\">from Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1756\"><div tabindex=\"-1\"><p>Carbonate rock that reacts with hot magmatic fluids, creating concentrated ore deposits, which include copper, iron, zinc, and gold.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1702\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1702\"><div tabindex=\"-1\"><p>Lake that forms next to a glacier because of crustal loading.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1022\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1022\"><div tabindex=\"-1\"><p>Where a dense ocean plate subducts beneath a less dense oceanic&nbsp;plate, causing an island arc to form.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_486\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_486\"><div tabindex=\"-1\"><p>By Pamputt (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\">CC BY-SA 4.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AAtomic_rearrangement_following_an_electron_capture.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2143\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2143\"><div tabindex=\"-1\"><p><!-- Here be dragons. --><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_502\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_502\"><div tabindex=\"-1\"><p>USGS, Public domain<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_487\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_487\"><div tabindex=\"-1\"><p>This is a copyrighted image from the CAMECA Archives<br \/>\nReproduction is authorized, under the terms of the GNU Free Documentation License.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_480\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_480\"><div tabindex=\"-1\"><p>NASA, public domain<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_481\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_481\"><div tabindex=\"-1\"><p>By Dirk H\u00fcnniger; Derivative work in english - Balajijagadesh [<a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Hydrogen_Deuterium_Tritium_Nuclei_Schmatic-en.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_482\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_482\"><div tabindex=\"-1\"><p>By Sbyrnes321 (Own work) [Public domain], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AHalflife-sim.gif\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2272\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2272\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2415\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2415\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_483\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_483\"><div tabindex=\"-1\"><p>By Inductiveload (Own work) [Public domain], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AAlpha_Decay.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1014\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1014\"><div tabindex=\"-1\"><p>Area behind the arc, which can be subject to compressional (causing thrusted mountain belts) or extensional (causing back-arc basins) forces.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1679\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1679\"><div tabindex=\"-1\"><p>Groves scratched in rock by glacial action.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1678\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1678\"><div tabindex=\"-1\"><p>A process where ice from the ends of glaciers falls off into the ocean.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1677\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1677\"><div tabindex=\"-1\"><p>The line between the zone of accumulation and the&nbsp;zone of ablation.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1690\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1690\"><div tabindex=\"-1\"><p>A terminal moraine that forms as a glacier melts.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_492\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_492\"><div tabindex=\"-1\"><p>Photo by Foto Chd (german wikipedia, https:\/\/de.wikipedia.org\/wiki\/Benutzer:Chd), used under the terms of the GNU Free Documentation License<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1514\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1514\"><div tabindex=\"-1\"><p>Any downhill movement of material, caused by gravity.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1683\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1683\"><div tabindex=\"-1\"><p>Steep spire carved by several glaciers.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1671\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1671\"><div tabindex=\"-1\"><p>Thick glaciers that cover continents during ice ages.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1005\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1005\"><div tabindex=\"-1\"><p>Place where two plates slide past each other, creating strike slip faults.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_491\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_491\"><div tabindex=\"-1\"><p>By Tim Bertelink (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/4.0\">CC BY-SA 4.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AHadean.png\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1519\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1519\"><div tabindex=\"-1\"><p>Slope angle where shear forces and normal forces are equal.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_748\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_748\"><div tabindex=\"-1\"><p>By Peter Kapitola (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/2.5\">CC BY-SA 2.5<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3ADarcy's_Law.png\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_490\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_490\"><div tabindex=\"-1\"><p>by Robert A. Rohde<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_1245\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_1245\"><div tabindex=\"-1\"><p>A rock made primarily of clay.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_489\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_489\"><div tabindex=\"-1\"><p>By Mike Christie (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AAccelerator_mass_spectrometer_schematic_for_radiocarbon.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2595\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2595\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_991\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_991\"><div tabindex=\"-1\"><p>A piece of foreign rock that has been incorporated into a magma body. This can be a different type of magma, or a mantle xenolith, a rock from the mantle brought up near the surface.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_601_2441\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_601_2441\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":291,"menu_order":8,"template":"","meta":{"pb_show_title":"","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[49],"contributor":[],"license":[],"class_list":["post-601","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":19,"_links":{"self":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/601","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/users\/291"}],"version-history":[{"count":2,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/601\/revisions"}],"predecessor-version":[{"id":1797,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/601\/revisions\/1797"}],"part":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/parts\/19"}],"metadata":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/601\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/media?parent=601"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapter-type?post=601"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/contributor?post=601"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/license?post=601"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}