{"id":840,"date":"2021-12-17T21:54:43","date_gmt":"2021-12-17T21:54:43","guid":{"rendered":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/13-deserts\/"},"modified":"2022-05-18T14:11:28","modified_gmt":"2022-05-18T14:11:28","slug":"13-deserts","status":"publish","type":"chapter","link":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/13-deserts\/","title":{"raw":"13 Deserts","rendered":"13 Deserts"},"content":{"raw":"[caption id=\"attachment_3488\" align=\"aligncenter\" width=\"1024\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/WS1-scaled.jpg\"><img class=\"wp-image-3488 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/WS1-scaled-1.jpg\" alt=\"The dune is made of white sand\" width=\"1024\" height=\"683\"><\/a> A playa filled with evaporite minerals (such as gypsum) erodes and forms ripple-covered dunes in White Sands National Monument, New Mexico.[\/caption]\n<h1><b>13 Deserts<\/b><\/h1>\n<b>KEY CONCEPTS<\/b>\n\nBy the end of this chapter, students should be able to:\n<ul>\n \t<li>Explain the defining characteristic of a desert and distinguish between the three broad categories of deserts<\/li>\n \t<li>Explain how geographic features, [pb_glossary id=\"2450\"]latitude[\/pb_glossary], atmospheric circulation, and Coriolis Effect influence where deserts are located<\/li>\n \t<li>List the primary desert [pb_glossary id=\"1754\"]weathering[\/pb_glossary] and [pb_glossary id=\"1755\"]erosion[\/pb_glossary] processes<\/li>\n \t<li>Identify desert landforms<\/li>\n \t<li>Explain how desert landforms are formed by [pb_glossary id=\"1755\"]erosion[\/pb_glossary] and [pb_glossary id=\"1757\"]deposition[\/pb_glossary]<\/li>\n \t<li>Describe the main types of sand [pb_glossary id=\"1947\"]dunes[\/pb_glossary] and the conditions that form them<\/li>\n \t<li>Identify the main features of the [pb_glossary id=\"1514\"]Basin and Range[\/pb_glossary] desert (United States)<\/li>\n<\/ul>\n[caption id=\"attachment_3489\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Koppen_World_Map_BWh.png\"><img class=\"wp-image-798 size-medium\" title=\"Peel, M. C., Finlayson, B. L., and McMahon, T. A. (University of Melbourne)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-300x184.png\" alt=\"The hot deserts are all near 30 north or south latitude.\" width=\"300\" height=\"184\"><\/a> World hot deserts (Koppen BWh)[\/caption]\n\nApproximately 30% of the Earth\u2019s [pb_glossary id=\"1980\"]terrestrial[\/pb_glossary] surface consists of deserts, which are defined as locations of low [pb_glossary id=\"1785\"]precipitation[\/pb_glossary]. While [pb_glossary id=\"1767\"]temperature[\/pb_glossary] extremes are often associated with deserts, they do not define them. Deserts exhibit extreme temperatures because of the lack of moisture in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary], including low humidity and scarce cloud cover. Without cloud cover, the Earth\u2019s surface absorbs more of the Sun\u2019s energy during the day and emits more heat at night.\n\n[caption id=\"attachment_3490\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Rainshadow.jpg\"><img class=\"wp-image-799 size-medium\" title=\"By en:User:Bariot \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-300x169.jpg\" alt=\"There is a dry and wet side to the mountain due to air movement.\" width=\"300\" height=\"169\"><\/a> Mountainous areas in front of the prevailing winds create a rain shadow.[\/caption]\n\nDeserts are not randomly located on the Earth\u2019s surface. Many deserts are located at latitudes between 15\u00b0 and 30\u00b0 in both hemispheres and at both the North and South Poles, created by prevailing wind circulation in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]. Sinking, dry air currents occurring at 30\u00b0 north and south of the equator produce <strong>[pb_glossary id=\"1494\"]trade winds[\/pb_glossary]<\/strong> that create deserts like the African Sahara and Australian Outback.\n\n[caption id=\"attachment_3491\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/OwensLake.jpg\"><img class=\"wp-image-800 size-medium\" title=\"By Picture prepared for Wikipedia by Adrian Pingstone in November 2003. (NASA)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-300x300.jpg\" alt=\"There are several ranges, some more snowy than others.\" width=\"300\" height=\"300\"><\/a> In this image from the ISS, the Sierra Nevada Mountains are perpendicular to prevailing westerly winds, creating a rain shadow to the east (down in the image). Note the dramatic decrease in snow on the Inyo Mountains.[\/caption]\n\n<span style=\"font-weight: 400\">Another type of desert is found in the <strong>rain shadow<\/strong> created from prevailing winds blowing over mountain ranges. As the wind drives air up and over mountains, atmospheric moisture is released as snow or rain. Atmospheric pressure is lower at higher elevations, causing the moisture-laden air to cool.\u00a0 Cool air holds less moisture than hot air, and [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] occurs as the wind rises up the mountain. After releasing its moisture on the windward side of the mountains, the dry air descends on the leeward or downwind side of the mountains to create an arid region with little [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] called a rain shadow.\u00a0 <\/span>Examples of rain-shadow deserts include the Western Interior Desert of North America and [pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary] of Chile, which is the Earth\u2019s driest, warm desert.\n\nFinally, [pb_glossary id=\"1489\"]polar deserts[\/pb_glossary], such as vast areas of the Antarctic and Arctic, are created from sinking cold air that is too cold to hold much moisture. Although they are covered with ice and snow, these deserts have very low average annual [pb_glossary id=\"1785\"]precipitation[\/pb_glossary]. As a result, Antarctica is Earth\u2019s driest [pb_glossary id=\"1653\"]continent[\/pb_glossary].\n\n[caption id=\"attachment_4732\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Rain-Shadow-Youtube-QR-Code.png\"><img class=\"wp-image-801 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-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\/iMu4dShS74w[\/embed]\n<h2><span style=\"font-weight: 400\"> 13.1 The Origin of Deserts<\/span><\/h2>\n<h3><b>13.1.1 Atmospheric circulation<\/b><\/h3>\nGeographic location, atmospheric circulation, and the Earth\u2019s rotation are the primary causal factors of deserts. Solar energy converted to heat is the engine that drives the circulation of air in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] and water in the oceans. The strength of the circulation is determined by how much energy is absorbed by the Earth\u2019s surface, which in turn is dependent on the average position of the Sun relative to the Earth. In other words, the Earth is heated unevenly depending on [pb_glossary id=\"2450\"]latitude[\/pb_glossary] and [pb_glossary id=\"2451\"]angle of incidence[\/pb_glossary]. [pb_glossary id=\"2450\"]Latitude[\/pb_glossary] is a line circling the Earth parallel to the equator and is measured in degrees. The equator is 0\u00b0 and the North and South Poles are 90\u00b0 N and 90\u00b0 S respectively (see the diagram of generalized atmospheric circulation on Earth). [pb_glossary id=\"2451\"]Angle of incidence[\/pb_glossary] is the angle made by a ray of sunlight shining on the Earth\u2019s surface. Tropical zones are located near the equator, where the [pb_glossary id=\"2450\"]latitude[\/pb_glossary] and [pb_glossary id=\"2451\"]angle of incidence[\/pb_glossary] are close to 0\u00b0, and receive high amounts of solar energy. The poles, which have latitudes and angles of incidence approaching 90\u00b0, receive little or almost no energy.\n\n[caption id=\"attachment_3492\" align=\"alignright\" width=\"500\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/01-Earth_Global_Circulation.jpg\"><img class=\"wp-image-802\" title=\"This file is in the public domain in the United States because it was solely created by NASA.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation.jpg\" alt=\"An illustration of the earth with three generalized circulation cells shown for each hemisphere.\" width=\"500\" height=\"429\"><\/a> Generalized atmospheric circlustion[\/caption]\n\nThe figure shows the generalized air circulation within the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary]. Three cells of circulating air span the space between the equator and poles in both hemispheres, the <strong>[pb_glossary id=\"1490\"]Hadley Cell[\/pb_glossary]<\/strong>, the <strong>Ferrel<\/strong> or <strong>Midlatitude Cell,<\/strong> and the <strong>[pb_glossary id=\"1493\"]Polar Cell[\/pb_glossary]<\/strong>. In the [pb_glossary id=\"1490\"]Hadley Cell[\/pb_glossary] located over the tropics and closest to the equatorial belt, the sun heats the air and causes it to rise. The rising air cools and releases its contained moisture as tropical rain. The rising dried air spreads away from the equator and toward the north and south poles, where it collides with dry air in the Ferrel Cell. The combined dry air sinks back to the Earth at 30\u00b0 [pb_glossary id=\"2450\"]latitude[\/pb_glossary]. This sinking drier air creates belts of predominantly high pressure at approximately 30\u00b0 north and south of the equator, called the horse latitudes.\u00a0 Arid zones between 15<sup>o<\/sup> and 30<sup>o<\/sup> north and south of the equator thus exist within which desert conditions predominate. The descending air flowing north and south in the Hadley and Ferrel cells also creates prevailing winds called [pb_glossary id=\"1494\"]trade winds[\/pb_glossary] near the equator, and [pb_glossary id=\"1495\"]westerlies[\/pb_glossary] in the temperate zone. Note the arrows indicating general directions of winds in these zones.\n\n[caption id=\"attachment_3493\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Central_Basin_and_Range_ecoregion.png\"><img class=\"wp-image-803 size-medium\" title=\"By C.E. Soulard, USGS\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion-300x264.png\" alt=\"The area covers most of Nevada, easternmost California, southern Idaho, and western Utah.\" width=\"300\" height=\"264\"><\/a> USGS Map of the Great Basin Desert.[\/caption]\n\nOther deserts, like the <strong>[pb_glossary id=\"1491\"]Great Basin Desert[\/pb_glossary]<\/strong> that covers parts of Utah and Nevada, owe at least part of their origin to other atmospheric phenomena. The [pb_glossary id=\"1491\"]Great Basin Desert[\/pb_glossary], while somewhat affected by sinking air effects from global circulation, is a rain-shadow desert. As westerly moist air from the Pacific rises over the Sierra Nevada and other mountains, it cools and loses moisture as condensation and [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] on the upwind or rainy side of the mountains.\n\n[caption id=\"attachment_3494\" align=\"alignright\" width=\"214\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Atacama_map.svg_.png\"><img class=\"wp-image-804 size-medium\" title=\"By cobaltcigs \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-214x300.png\" alt=\"It is in west-central South America\" width=\"214\" height=\"300\"><\/a> Map of the Atacama desert (yellow) and surrounding related climate areas (orange).[\/caption]\n\nOne of the driest places on Earth is the <strong>[pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary]<\/strong> of northern Chile. The [pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary] occupies a strip of land along Chile\u2019s [pb_glossary id=\"1968\"]coast[\/pb_glossary] just north of [pb_glossary id=\"2450\"]latitude[\/pb_glossary] 30\u00b0S, at the southern edge of the trade-wind belt. The desert lies west of the Andes Mountains, in the rain shadow created by prevailing [pb_glossary id=\"1494\"]trade winds[\/pb_glossary] blowing west. As this warm moist air crossing the Amazon [pb_glossary id=\"508\"]basin[\/pb_glossary] meets the eastern edge of the mountains, it rises, cools, and precipitates much of its water out as rain. Once over the mountains, the cool, dry air descends onto the [pb_glossary id=\"1492\"]Atacama desert[\/pb_glossary].\u00a0 Onshore winds from the Pacific are cooled by the Peru (Humboldt) ocean current. This super-cooled air holds almost no moisture and, with these three factors, some locations in the [pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary] have received no measured [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] for several years. This desert is the driest, non-polar location on Earth.\n\n[caption id=\"attachment_3495\" align=\"alignleft\" width=\"277\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/polar_vortex.jpg\"><img class=\"wp-image-805 size-medium\" title=\"By National Oceanic and Atmospheric Administration - Pacific Marine Environmental Laboratory\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-277x300.jpg\" alt=\"The sinking air is centered just north of Greenland, close to the north pole.\" width=\"277\" height=\"300\"><\/a> The polar vortex of mid-November, 2013. This cold, descending air (shown in purple) is characteristic of polar circulation.[\/caption]\n\nNotice in the figure that the polar regions are also areas of predominantly high pressure created by descending cold dry air, the <strong>[pb_glossary id=\"1493\"]Polar Cells[\/pb_glossary]<\/strong>. As with the other cells, cold air, which holds much less moisture than warm air, descends to create [pb_glossary id=\"1489\"]polar deserts[\/pb_glossary]. This is why historically, land near the north and south poles has always been so dry.\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n<h3><b>13.1.2 Coriolis Effect<\/b><\/h3>\n[caption id=\"attachment_3496\" align=\"alignleft\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.2_Corioliskraftanimation.gif\"><img class=\"wp-image-806 size-full\" title=\"By Hubi\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2_Corioliskraftanimation.gif\" alt=\"Animation illustrating a ball thrown on a rotating disc. Viewed from the perspective of a stationary viewer on the disc, it appears to follow a curved path.\" width=\"200\" height=\"283\"><\/a> In the inertial frame of reference of the top picture, the ball moves in a straight line. The observer, represented as a red dot, standing in the rotating frame of reference sees the ball following a curved path. This perceived curvature is due to the Coriolis Effect and centrifugal forces.[\/caption]\n\n&nbsp;\n\nThe Earth rotates toward the east where the sun rises. Think of spinning a weight on a string around your head. The speed of the weight depends on the length of the string. The speed of an object on the rotating Earth depends on its horizontal distance from the Earth\u2019s [pb_glossary id=\"503\"]axis[\/pb_glossary] of rotation. Higher latitudes are a smaller distance from the Earth\u2019s rotational [pb_glossary id=\"503\"]axis[\/pb_glossary], and therefore do not travel as fast eastward as lower [pb_glossary id=\"2450\"]latitudes[\/pb_glossary] that are closer to the equator. When a fluid like air or water moves from a lower [pb_glossary id=\"2450\"]latitude[\/pb_glossary] to a higher [pb_glossary id=\"2450\"]latitude[\/pb_glossary], the fluid maintains its momentum from moving at a higher speed, so it will travel relatively faster eastward than the Earth beneath at the higher latitudes. This factor causes deflection of movements that occur in north-south directions.\n\n[caption id=\"attachment_3497\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Coriolis-Effect-E-W.jpg\"><img class=\"wp-image-807 size-medium\" title=\"From L. Cameron Mosher\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-300x204.jpg\" alt=\"Effect of gravity and the centripetal force to produce the Coriolis Effect on an E-W moving mass on the rotating Earth\" width=\"300\" height=\"204\"><\/a> Forces ting on a mass moving East-West on the rotating Earth that produce the Coriolis Effect[\/caption]\n\nAnother factor in the Coriolis effect also causes deflection of east-west movement due to the angle between the centripetal effect of Earth\u2019s spin and gravity pulling toward the earth\u2019s center (see figure). This produces a net deflection toward the equator. The total Coriolis deflection on a mass moving in any direction on the rotating Earth results from a combination of these two factors.\n\nSince each hemisphere has three atmospheric cells moving respectively north and south relative to the Earth beneath them, the Coriolis effect deflects these moving air masses to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The Coriolis effect also deflects moving masses of water in the ocean currents.\n\nFor example, in the northern hemisphere [pb_glossary id=\"1490\"]Hadley Cell[\/pb_glossary], the lower altitude air currents are flowing south towards the equator. These are deflected to the right (or west) by the Coriolis effect. This deflected air generates the prevailing [pb_glossary id=\"1494\"]trade winds[\/pb_glossary] that European sailors used to cross the Atlantic Ocean and reach South America and the Caribbean Islands in their tall ships. This air movement is mirrored in the [pb_glossary id=\"1490\"]Hadley Cell[\/pb_glossary] in the southern hemisphere; the lower altitude air current flowing equatorward is deflected to the left, creating [pb_glossary id=\"1494\"]trade winds[\/pb_glossary] that blow to the northwest.\n\n[caption id=\"attachment_3498\" align=\"alignright\" width=\"256\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.3_Coriolis_effect14.png\"><img class=\"wp-image-808 size-full\" title=\"Used by permission of Anders Persson under under the terms of the GNU Free Documentation License.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14.png\" alt=\"Illustration of the Earth with circles showing the Coriolis deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.\" width=\"256\" height=\"256\"><\/a> Inertia of air masses caused by the Coriolis Effect in the absence of other forces[\/caption]\n\nIn the northern Mid-[pb_glossary id=\"2450\"]Latitude[\/pb_glossary] or Ferrel Cell, surface air currents flow from the horse latitudes ([pb_glossary id=\"2450\"]latitude[\/pb_glossary] 30\u00b0) toward the North Pole, and the Coriolis effect deflects them toward the east, or to the right, producing the zone of westerly winds. In the southern hemisphere Mid-[pb_glossary id=\"2450\"]Latitude[\/pb_glossary] or Ferrel Cell, the poleward flowing surface air is deflected to the left and flows southeast creating the Southern Hemisphere [pb_glossary id=\"1495\"]westerlies[\/pb_glossary].\n\nAnother Coriolis-generated deflection produces the [pb_glossary id=\"1493\"]Polar Cells[\/pb_glossary]. At 60<sup>o<\/sup> north and south [pb_glossary id=\"2450\"]latitude[\/pb_glossary], relatively warmer rising air\u00a0 flows poleward cooling and converging at the poles where it sinks in the polar high. This sinking dry air creates the [pb_glossary id=\"1493\"]polar deserts[\/pb_glossary], the driest deserts on Earth. Persistence of ice and snow is a result of cold temperatures at these dry locations.\n\n[caption id=\"attachment_3499\" align=\"alignleft\" width=\"393\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.4_Corrientes-oceanicas.png\"><img class=\"wp-image-809\" title=\" This work is in the public domain in the United States\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-300x157.png\" alt=\"Warm currents are red, blue currents are blue.\" width=\"393\" height=\"205\"><\/a> Gyres of the Earth\u2019s oceans.[\/caption]\n\nThe Coriolis effect operates on all motions on the Earth. Artillerymen must take the Coriolis effect into account on ballistic trajectories when making long-distance targeting calculations. Geologists note how its effect on air and [pb_glossary id=\"1659\"]oceanic[\/pb_glossary] currents creates deserts in designated zones around the Earth as well as the surface currents in the ocean. The Coriolis effect causes the ocean [pb_glossary id=\"1478\"]gyres[\/pb_glossary] to turn clockwise in the northern hemisphere and counterclockwise in the southern. It also affects [pb_glossary id=\"756\"]weather[\/pb_glossary] by creating high-altitude, polar jet [pb_glossary id=\"2212\"]streams[\/pb_glossary] that sometimes push lobes of cold arctic air into the temperate zone, down to as far as [pb_glossary id=\"2450\"]latitude[\/pb_glossary] 30\u00b0 from the usual 60\u00b0. It also causes low pressure systems and intense tropical storms to rotate counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.\n\n[caption id=\"attachment_4733\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/The-Coriolis-Effect-Explained-Youtube-QR-Code.png\"><img class=\"size-thumbnail wp-image-810\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-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&nbsp;\n\n[embed]https:\/\/www.youtube.com\/embed\/HIyBpi7B-dE[\/embed]\n\n<em><span style=\"font-size: 10pt\">Explanation of Coriolis Effect.<\/span><\/em>\n\n&nbsp;\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"89\"]\n\n[caption id=\"attachment_4727\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.1-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-811\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-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 section13.1 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">13.2 Desert weathering and erosion<\/span><\/h2>\n[caption id=\"attachment_3500\" align=\"alignleft\" width=\"360\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CNL9-scaled.jpg\"><img class=\"wp-image-3500\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CNL9-scaled-1.jpg\" alt=\"There is an arch and spires\" width=\"360\" height=\"308\"><\/a> Weathering and erosion of Canyonlands National Park has created a unique landscape, including arches, cliffs, and spires.[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1754\"]Weathering[\/pb_glossary] takes place in desert climates by the same means as other climates, only at a slower rate. While higher temperatures typically spur faster [pb_glossary id=\"1890\"]chemical weathering[\/pb_glossary], water is the main agent of [pb_glossary id=\"1754\"]weathering[\/pb_glossary], and lack of water slows both mechanical and [pb_glossary id=\"1890\"]chemical weathering[\/pb_glossary]. <span class=\"NormalTextRun SCXW70160266 BCX0\">Low [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] levels also mean less <\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">[pb_glossary id=\"2205\"]runoff[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">as well as [pb_glossary id=\"254\"]ice wedging[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">.<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0W<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">hen<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">[pb_glossary id=\"1785\"]precipitation[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">does occur<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0in the desert, it is\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">often\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">heavy and may result in<\/span> [pb_glossary id=\"1506\"]flash floods[\/pb_glossary] in which a lot of material may be dislodged and moved quickly.<\/span>\n\n[caption id=\"attachment_3501\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Newspaper_Rock_Full.jpg\"><img class=\"wp-image-813 size-medium\" title=\"By Cacophony\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-300x200.jpg\" alt=\"The rock is dark brown with petroglyphs\" width=\"300\" height=\"200\"><\/a> Newspaper rock, near Canyonlands National Park, has many petroglyphs carved into desert varnish.[\/caption]\n\nOne unique [pb_glossary id=\"1754\"]weathering[\/pb_glossary] product in deserts is <strong>[pb_glossary id=\"1496\"]desert varnish[\/pb_glossary]<\/strong>. Also known as desert patina or rock rust, this is thin dark brown layers of clay [pb_glossary id=\"1765\"]minerals[\/pb_glossary] and iron and manganese [pb_glossary id=\"971\"]oxides[\/pb_glossary] that form on very stable surfaces within arid environments. The exact way this material forms is still unknown, though cosmogenic and biologic mechanisms have been proposed.\n\n&nbsp;\n\n[caption id=\"attachment_3502\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MN7.jpg\"><img class=\"wp-image-814 size-medium\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-300x225.jpg\" alt=\"The left of the picture is full of brown dust\" width=\"300\" height=\"225\"><\/a> A dust storm (haboob) hits the Mongolian Gobi.[\/caption]\n\nWhile water is still the dominant agent of [pb_glossary id=\"1755\"]erosion[\/pb_glossary] in most desert environments, wind is a notable agent of [pb_glossary id=\"1754\"]weathering[\/pb_glossary] and [pb_glossary id=\"1755\"]erosion[\/pb_glossary] in many\u00a0deserts. This includes suspended [pb_glossary id=\"1756\"]sediment[\/pb_glossary] traveling in\u00a0<strong>[pb_glossary id=\"1497\"]haboobs[\/pb_glossary]<\/strong>, or large dust storms, that frequent deserts. Deposits of windblown dust are called <b>[pb_glossary id=\"1987\"]loess[\/pb_glossary]<\/b>. [pb_glossary id=\"1987\"]Loess[\/pb_glossary] deposits cover wide areas of the midwestern United States, much of it from rock flour that melted out of the [pb_glossary id=\"1519\"]ice sheets[\/pb_glossary] during the last [pb_glossary id=\"747\"]ice age[\/pb_glossary]. Loess was also blown from desert regions in the West. Possessing lower energy than water, wind transport nevertheless moves sand, silt, and dust<span style=\"font-weight: 400\">. As noted in <a href=\"http:\/\/opengeology.org\/textbook\/11-water\/\">chapter 11<\/a>, the load carried by a fluid (air is a fluid like water) is distributed among [pb_glossary id=\"2222\"]bedload[\/pb_glossary] and [pb_glossary id=\"2223\"]suspended load[\/pb_glossary]. As with water, in wind these components depend on wind velocity<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\">\u00a0<\/span>\n\n<span style=\"font-weight: 400\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.5_Saltation-mechanics.gif\"><img class=\"alignright wp-image-815 size-full\" title=\"By NASA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.5_Saltation-mechanics.gif\" alt=\"Sand grains bouncing and splashing out other grains in saltation.\" width=\"270\" height=\"176\"><\/a>Sand size material moves by a process called <\/span><b>[pb_glossary id=\"1498\"]saltation[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> in which sand grains are lifted into the moving air and carried a short distance where they drop and splash into the surface dislodging other sand grains which are then carried a short distance and splash dislodging still others<\/span><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3504\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg\"><img class=\"wp-image-364 size-medium\" title=\"Photo by Mark A. Wilson and released into the Public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg\" alt=\"Windblown sand grains showing rounding and frosted surfaces due to transport b wind.\" width=\"300\" height=\"225\"><\/a> Enlarged image of frosted and rounded windblown sand grains[\/caption]\n\n<span style=\"font-weight: 400\">Since saltating sand grains are constantly impacting other sand grains, wind blown sand grains are commonly quite well rounded with frosted surfaces. [pb_glossary id=\"1498\"]Saltation[\/pb_glossary] is a cascading effect of sand movement creating a zone of wind blown sand up to a meter or so above the ground. This zone of saltating sand is a powerful [pb_glossary id=\"1755\"]erosive[\/pb_glossary] agent in which [pb_glossary id=\"1023\"]bedrock[\/pb_glossary] features are effectively sandblasted. The fine-grained [pb_glossary id=\"2223\"]suspended load[\/pb_glossary] is effectively sorted from the sand near the surface carrying the silt and dust into [pb_glossary id=\"1497\"]haboobs[\/pb_glossary]. Wind is thus an effective [pb_glossary id=\"1907\"]sorting[\/pb_glossary] agent separating sand and dust sized (\u226470 \u00b5m) particles <span class=\"TextRun BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW201347767\">(<\/span><\/span><a class=\"Hyperlink BCX0 SCXW201347767\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/%22%20\/l%20%22532_Detrital_Sedimentary_Rocks_Clastic\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"FieldRange BCX0 SCXW201347767\"><span class=\"TextRun Underlined BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun CommentStart BCX0 SCXW201347767\" data-ccp-charstyle=\"Hyperlink\">See Chapter 5<\/span><\/span><\/span><\/a><span class=\"TextRun BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW201347767\">)<\/span><\/span><\/span><span style=\"font-weight: 400\">.\u00a0When wind velocity is high enough to slide or roll materials along the surface, the process is called <strong>[pb_glossary id=\"1499\"]creep[\/pb_glossary]<\/strong>. <\/span>\n\n<span style=\"font-weight: 400\" data-wp-editing=\"1\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.6_2006_1205_135618-DVNP-RACETRACK.jpg\"><img class=\"alignleft wp-image-816 size-medium\" title=\"Source: This image is used under the terms of the GNU Free Documentation License\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-272x300.jpg\" alt=\"A large rock has slid over the playa surface leaving a track in the mud.\" width=\"272\" height=\"300\"><\/a>One extreme version of [pb_glossary id=\"4823\"]sediment[\/pb_glossary] movement was shrouded in mystery for years: <\/span><b>[pb_glossary id=\"1500\"]Sliding stones[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. Also called [pb_glossary id=\"1500\"]sailing stones[\/pb_glossary] and [pb_glossary id=\"1500\"]sliding rocks[\/pb_glossary], these are large moving boulders along flat surfaces in deserts, leaving trails. This includes the famous example of the Racetrack [pb_glossary id=\"1984\"]Playa[\/pb_glossary] in Death Valley National Park, California<\/span><span style=\"font-weight: 400\">. For years, scientists and enthusiasts attempted to explain their movement, with little definitive results<\/span><span style=\"font-weight: 400\">. In recent years, several experimental and observational studies have confirmed that the stones, imbedded in thin layers of ice, are propelled by friction from high winds<\/span><span style=\"font-weight: 400\">. These studies include measurements of actual movement, as well as re-creations of the conditions, with resulting movement in the lab.<\/span>\n\n[caption id=\"attachment_3507\" align=\"alignleft\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.8_VentifactMojaveDesert031511-scaled.jpg\"><img class=\"wp-image-3507 size-thumbnail\" title=\"&quot;Source:\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.8_VentifactMojaveDesert031511-scaled-1.jpg\" alt=\"Rock on desert floor polished on multiple sides by sandblasting.\" width=\"150\" height=\"150\"><\/a> Ventifact from Mojave Desert near Barstow, CA[\/caption]\n\n<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.7_Yardang_Im_Salar_de_Uyuni.jpg\"><img class=\"alignright wp-image-818\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-300x223.jpg\" alt=\"Large rock standing on a base narrowed by sandblasting.\" width=\"202\" height=\"150\"><\/a>\n\n&nbsp;\n\n<span style=\"font-weight: 400\">The zone of saltating sand is an effective agent of [pb_glossary id=\"1755\"]erosion[\/pb_glossary] through sand abrasion. A [pb_glossary id=\"1023\"]bedrock[\/pb_glossary] outcrop which has such a sandblasted shape is called a <\/span><b>[pb_glossary id=\"1501\"]yardang[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. Rocks and boulders lying on the surface may be blasted and polished by saltating sand. When predominant wind directions shift, multiple sandblasted and polished faces may appear. Such wind abraded desert rocks are called <\/span><b>[pb_glossary id=\"1502\"]ventifacts[\/pb_glossary]<\/b><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3525\" align=\"alignright\" width=\"253\"]<a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/13.9_Blowout_Earth_TX.jpg\"><img class=\"wp-image-819\" title=\"Source: This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-300x184.jpg\" alt=\"Photo of land level lowered by wind causing a blowout.\" width=\"253\" height=\"155\"><\/a> Blowout in Texas[\/caption]\n\n<span style=\"font-weight: 400\">In places with sand and silt accumulations, clumps of vegetation often anchor [pb_glossary id=\"1756\"]sediment[\/pb_glossary] on the desert surface. Yet, winds may be sufficient to remove materials not anchored by vegetation. The bowl-shaped depression remaining on the surface is called a <\/span><b>[pb_glossary id=\"1503\"]blowout[\/pb_glossary]<\/b><span style=\"font-weight: 400\">.<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"90\"]\n\n[caption id=\"attachment_4728\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.2-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-820\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-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 13.2 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">13.3 Desert landforms<\/span><\/h2>\n[caption id=\"attachment_3510\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.10_Alluvial_Fan.jpg\"><img class=\"wp-image-821 size-medium\" title=\"Source: This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-300x158.jpg\" alt=\"Looking down on semi-circular fan-shaped deposit where a stream emerges from a canyon in Death Valley\" width=\"300\" height=\"158\"><\/a> Aerial image of alluvial fan in Death Valley[\/caption]\n\n<span style=\"font-weight: 400\"><span class=\"NormalTextRun BCX0 SCXW147497739\">In the American Southwest,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">as\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"2212\"]streams[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">emerge into the valleys<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0from<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">adjacent\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">mountains<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">, they<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">create desert landforms called [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fans<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">. When the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"2212\"]stream[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">emerges from<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0narrow\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 BCX0 SCXW147497739\">canyon,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0the flow is no longer constrained by the canyon walls<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0and spreads out<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">. At the\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">lower slope angle<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the water<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">slows down and\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">drops its coarser load<\/span>. As the channel fills with this conglomeratic material, the [pb_glossary id=\"2212\"]stream[\/pb_glossary] is deflected around it. <span class=\"NormalTextRun BCX0 SCXW147497739\">This\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">deposited material deflects\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"2212\"]stream[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">into\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"1742\"]system[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">of radial distributar<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">y channels in a\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">process<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun AdvancedProofingIssueV2 BCX0 SCXW147497739\">similar to<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">how\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"1979\"]delta[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">is made\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">by a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">[pb_glossary id=\"2212\"]river[\/pb_glossary]<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">entering a body of water<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">.<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span>This process develops a [pb_glossary id=\"1742\"]system[\/pb_glossary] of radial distributaries and constructs a fan shaped feature called an <\/span><b>[pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fan<\/b><b>.\u00a0<\/b>\n\n[caption id=\"attachment_3511\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.11_Bajada_at_FriscoMountainUT-scaled.jpg\"><img class=\"wp-image-3511 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.11_Bajada_at_FriscoMountainUT-scaled-1.jpg\" alt=\"Photo of mountain where alluvial fans have coalesced into an apron of sedimant along the mountain front.\" width=\"300\" height=\"200\"><\/a> Bajada along Frisco Peak in Utah[\/caption]\n\n&nbsp;\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1982\"]Alluvial[\/pb_glossary] fans continue to grow and may eventually coalesce with neighboring fans to form an apron of [pb_glossary id=\"1652\"]alluvium[\/pb_glossary] along the mountain front called a <\/span><b>[pb_glossary id=\"1504\"]bajada[\/pb_glossary]<\/b><span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3512\" align=\"alignleft\" width=\"225\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.12_Inselbergs_in_Mojave_Desert.jpg\"><img class=\"wp-image-823 size-medium\" title=\"Source: Image from USGS\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert-225x300.jpg\" alt=\"Aerial photo of mountain remnants surrounded by their own erosional debris.\" width=\"225\" height=\"300\"><\/a> Inselbergs in Mojave Desert[\/caption]\n\nAs the mountains erode away and their [pb_glossary id=\"1756\"]sediment[\/pb_glossary] accumulates first in [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fans, then [pb_glossary id=\"1504\"]bajadas[\/pb_glossary], the mountains eventually are buried in their own erosional debris. Such buried mountain remnants are called <b>[pb_glossary id=\"1505\"]inselbergs[\/pb_glossary]<\/b><span style=\"font-weight: 400\">, \u201cisland mountains,\u201d as first described by the German geologist Wilhelm Bornhardt <span class=\"TextRun BCX0 SCXW36294923\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW36294923\">(1864\u20131946)<\/span><\/span>.<\/span>\n\n[caption id=\"attachment_3513\" align=\"alignright\" width=\"244\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.14a_dolansprings_oli_2013088_playa_lrg-scaled.jpg\"><img class=\"wp-image-3513\" title=\"Satellite image from NASA.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.14a_dolansprings_oli_2013088_playa_lrg-scaled-1.jpg\" alt=\"Satellite image of desert dry lake or playa surrounded by mountains.\" width=\"244\" height=\"183\"><\/a> Satellite image of desert playa surrounded by mountains[\/caption]\n\nWhere the desert valley is an enclosed [pb_glossary id=\"508\"]basin[\/pb_glossary], i.e. [pb_glossary id=\"2212\"]streams[\/pb_glossary] entering it do not drain out, the water is removed by evaporation and a dry lake [pb_glossary id=\"1936\"]bed[\/pb_glossary] is formed called a <b>[pb_glossary id=\"1984\"]playa[\/pb_glossary].<\/b>\n\n[caption id=\"attachment_3514\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.13_Dry_Wash_in_PEFO_NP.jpg\"><img class=\"wp-image-825 size-medium\" title=\"By Finetooth\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-300x181.jpg\" alt=\"Photo of dry wash that carries water only after rains.\" width=\"300\" height=\"181\"><\/a> Dry wash (or ephemeral stream)[\/caption]\n\n[pb_glossary id=\"1984\"]Playas[\/pb_glossary] are among the flattest of all landforms. Such a dry lake [pb_glossary id=\"1936\"]bed[\/pb_glossary] may cover a large area and be filled after a heavy thunderstorm to only a few inches deep. [pb_glossary id=\"1984\"]Playa[\/pb_glossary] lakes and desert [pb_glossary id=\"2212\"]streams[\/pb_glossary] that contain water only after rainstorms are called <b>intermittent\u00a0<\/b><span style=\"font-weight: 400\">\u00a0or <\/span><b>[pb_glossary id=\"2211\"]ephemeral[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. <span class=\"TextRun SCXW175656738 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW175656738 BCX0\">Because of intense thunderstorms, the volume of water transported by [pb_glossary id=\"2211\"]ephemeral[\/pb_glossary] d<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">rainage<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">in arid environments can be substantial during a short [pb_glossary id=\"1244\"]period[\/pb_glossary] of time. Desert soil structures\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">lack organic matter that<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">promotes <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">infiltration<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">by absorbing water<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">.<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">Instead of percolating into the [pb_glossary id=\"250\"]soil[\/pb_glossary], the [pb_glossary id=\"2205\"]runoff[\/pb_glossary]\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">compacts the\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">ground\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">surface<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">, making the [pb_glossary id=\"250\"]soil[\/pb_glossary]\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW175656738 BCX0\">hydrophobic<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0or water-repellant<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">. Because of t<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">his <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">hardpan surface, [pb_glossary id=\"2211\"]ephemeral[\/pb_glossary] [pb_glossary id=\"2212\"]streams[\/pb_glossary] may <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">gather water\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">across\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">large areas<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">suddenly fill<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">ing<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\"> with water from storms many miles away<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><\/span><span class=\"EOP SCXW175656738 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/span><span style=\"font-weight: 400\">\u00a0\u00a0<\/span>\n\n[caption id=\"attachment_3515\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.15_Flash_flood_in_the_desert-1.jpg\"><img class=\"wp-image-826 size-medium\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-300x225.jpg\" alt=\"Formerly dry wash now a violent torrent after heavy rain in the area\" width=\"300\" height=\"225\"><\/a> Flash flood in a dry wash[\/caption]\n\n<span class=\"TextRun SCXW131970605 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">H<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">igh-volume<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">[pb_glossary id=\"2211\"]ephemeral[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0f<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">lows<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, called\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">[pb_glossary id=\"1506\"]flash floods[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">,<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0may move as sheet flows<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0or [pb_glossary id=\"1507\"]sheetwash[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, as well as\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">be\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">channeled through normally dry [pb_glossary id=\"2210\"]arroyos[\/pb_glossary] or canyons<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">F<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">lash floods<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">are a major factor in desert<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">[pb_glossary id=\"1757\"]deposition[\/pb_glossary].<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">Dry<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">channels\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">can<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">fill quickly<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0with [pb_glossary id=\"2211\"]ephemeral[\/pb_glossary] [pb_glossary id=\"2208\"]drainage[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, creating<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">a mass of water and debris that charges down\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">the [pb_glossary id=\"2210\"]arroyo[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">and\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">even overflowing the banks.<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">[pb_glossary id=\"1506\"]Flash floods[\/pb_glossary] pose\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">a serious\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">hazard\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">for desert travelers\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">because the storm activity feeding the [pb_glossary id=\"2205\"]runoff[\/pb_glossary] may be <\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">miles away<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">People\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">hiking\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">or camping\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">in [pb_glossary id=\"2210\"]arroyos[\/pb_glossary]\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">that have been bone dry for months, or years,\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">have been swept away by sudden<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">[pb_glossary id=\"1506\"]flash floods[\/pb_glossary].<\/span><\/span><span class=\"EOP SCXW131970605 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span>\n<h3><b>13.3.1 Sand<\/b><\/h3>\n[caption id=\"attachment_3516\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.16_Sahara_Desert_in_Jalu_Libya.jpeg\"><img class=\"size-medium wp-image-3516\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.16_Sahara_Desert_in_Jalu_Libya.jpeg\" alt=\"The Sahara Desert, a sea of sand or erg.\" width=\"300\" height=\"225\"><\/a> Sahara Desert, a sand sea or erg[\/caption]\n\n<span class=\"TextRun SCXW253049173 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">T<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">he popular concept of a typical desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0is a\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">broad expanse of\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">. Geologically,\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">s<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">are\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">defined by <\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">a lack of water and arid regions resembling a sea of sand belong to the category of desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0called an<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><strong><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1508\"]erg[\/pb_glossary]<\/span><\/strong><span class=\"NormalTextRun SCXW253049173 BCX0\">. An<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1508\"]erg[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">consists of\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">fine-grained<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, loose<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0grains,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">often blown by<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">wind, or\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1986\"]aeolian[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">forces<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0into<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1947\"]dunes[\/pb_glossary]. Probably the\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">best known<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1508\"]erg[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">is the\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">Rub\u2019 al Khali<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, which means\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Empty Quarter<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">of\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Arabia<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">n Peninsula.<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">E<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">rgs<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">are also found in<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Great Sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1947\"]Dunes[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">National Park<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Colorado<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">)<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, Little Sahara Recreation Area<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Utah<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">), White Sands National Monument<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">New Mexico<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">), and parts of Death Valley National Park<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">California<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">).\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1508\"]Ergs[\/pb_glossary] are not restricted to\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">deserts<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, but may\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">form<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">anywhere\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">re<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">is a\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">substantial\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">supply\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">of sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, including as\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">far north as 60\u00b0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0N\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">in Saskatchewan<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Canada, in the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Athabasca Sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1947\"]Dunes[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Provincial\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">Park<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">.<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0Coastal<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">[pb_glossary id=\"1508\"]ergs[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">exist along\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">lakes and oceans<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0as well<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, and\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">examples are\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">found in Oregon, Michigan, and Indiana.<\/span><\/span><span class=\"EOP SCXW253049173 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span>\n\n<span style=\"font-weight: 400\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.17_Formation-of-cross_beds.gif\"><img class=\"alignright size-full wp-image-828\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.17_Formation-of-cross_beds.gif\" alt=\"Illustrating the formation of\" width=\"290\" height=\"74\"><\/a>An internal cross section of a sand [pb_glossary id=\"1947\"]dune[\/pb_glossary] shows a feature called <\/span><b>[pb_glossary id=\"1509\"]cross bedding[\/pb_glossary]<\/b><span style=\"font-weight: 400\">. As wind blows up the windward side of the [pb_glossary id=\"1947\"]dune[\/pb_glossary], it carries sand to the [pb_glossary id=\"1947\"]dune[\/pb_glossary] crest depositing layers of sand parallel to the windward (or \u201cstoss\u201d) side. The sand builds up the crest of the [pb_glossary id=\"1947\"]dune[\/pb_glossary] and pours over the top until the leeward (downwind or slip) face of the [pb_glossary id=\"1947\"]dune[\/pb_glossary] reaches the <\/span><b>[pb_glossary id=\"2193\"]angle of repose[\/pb_glossary],\u00a0<\/b><span style=\"font-weight: 400\">the maximum angle which will support the slip face. [pb_glossary id=\"1947\"]Dunes[\/pb_glossary] are unstable features and move as the sand erodes from the stoss side and continues to drop down the leeward side covering previous stoss and slip-face layers and creating the cross [pb_glossary id=\"1936\"]beds[\/pb_glossary]. Mostly, these are reworked over and over again, but occasionally, the features are preserved in a depression, then lithified. Shifting wind directions and abundant sand sources create chaotic patterns of cross [pb_glossary id=\"1936\"]beds[\/pb_glossary] like those seen in Zion National Park of Utah.\u00a0<\/span>\n\n[caption id=\"attachment_3518\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.18_Sandstone_showing_Cross-bedding_Zion_National_Park_Utah_USA-scaled.jpg\"><img class=\"size-medium wp-image-3518\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.18_Sandstone_showing_Cross-bedding_Zion_National_Park_Utah_USA-scaled-1.jpg\" alt=\"Image of cross bedding in ancient sand dunes at Zion National Park, Utah.\" width=\"300\" height=\"200\"><\/a> Cross beds in the Navajo Sandstone at Zion National Park[\/caption]\n\n<span class=\"TextRun SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW213184174 BCX0\">In the<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">[pb_glossary id=\"479\"]Mesozoic[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0[pb_glossary id=\"1243\"]Era[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">, Utah was covered by a series of<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1508\"]ergs[\/pb_glossary],\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">with\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">thickest\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">being\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">in Southern Utah<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">which lithified into [pb_glossary id=\"1912\"]sandstone[\/pb_glossary] (<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW213184174 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#531_Lithification_and_Diagenesis\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW213184174 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW213184174 BCX0\">)<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">. Perhaps the best known of these<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1912\"]sandstone[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"2038\"]formations[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">is the Navajo<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1912\"]Sandstone[\/pb_glossary] of [pb_glossary id=\"486\"]Jurassic[\/pb_glossary] age. This <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1912\"]sandstone[\/pb_glossary]\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">form<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">ation<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">consists of\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">dramatic cliffs and spires in Zion National Park and covers a large part of the Colorado Plateau.\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">In\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Arches National Park, a later series of sand<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1947\"]dunes[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">covered the Navajo [pb_glossary id=\"1912\"]Sandstone[\/pb_glossary] and lithified to become the Entrada [pb_glossary id=\"2038\"]Formation[\/pb_glossary] also during the [pb_glossary id=\"486\"]Jurassic[\/pb_glossary]. [pb_glossary id=\"1755\"]Erosion[\/pb_glossary] of overlying layers <\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">exposed fins of <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">the underlying\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Entrada<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">[pb_glossary id=\"1912\"]Sandstone[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0and\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">carved out weaker parts of the fins forming the <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">arches.<\/span><\/span><span class=\"EOP SCXW213184174 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span>\n\n[caption id=\"attachment_3504\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg\"><img class=\"size-medium wp-image-364\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg\" alt=\"Windblown sand grains showing rounding and frosted surfaces due to transport b wind.\" width=\"300\" height=\"225\"><\/a> Enlarged image of frosted and rounded windblown sand grains[\/caption]\n\n<span style=\"font-weight: 400\">As the cements that hold the grains together in these modern sand cliffs disintegrate and the freed grains gather at the base of the cliffs and move down the washes, sand grains may be recycled and redeposited. These [pb_glossary id=\"479\"]Mesozoic[\/pb_glossary] sand [pb_glossary id=\"1508\"]ergs[\/pb_glossary] may represent ancient [pb_glossary id=\"967\"]quartz[\/pb_glossary] sands recycled many times from [pb_glossary id=\"1753\"]igneous[\/pb_glossary] origins in the early [pb_glossary id=\"1270\"]Precambrian[\/pb_glossary], just passing now through another cycle of [pb_glossary id=\"1755\"]erosion[\/pb_glossary] and [pb_glossary id=\"1757\"]deposition[\/pb_glossary]. <\/span><span style=\"font-weight: 400\">An example of this is Coral Pink Sand [pb_glossary id=\"1947\"]Dunes[\/pb_glossary] State Park in Southwestern Utah, which contains sand that is being eroded from the Navajo [pb_glossary id=\"1912\"]Sandstone[\/pb_glossary] to form new [pb_glossary id=\"1947\"]dunes[\/pb_glossary].<\/span>\n<h4><b>Dune Types<\/b><\/h4>\n[caption id=\"attachment_3519\" align=\"alignright\" width=\"190\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.20a_Barchan_dune_field_coastal_Brazil.jpg\"><img class=\"wp-image-830\" title=\"Source: NASA image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-300x300.jpg\" alt=\"Satellite image of a field of bnarchan dunes, eqach showing the fcharacteristic shape of sand wings wrapped around the bare dune court. The wionmgs point in the direction of prevailing winds.\" width=\"190\" height=\"190\"><\/a> NASA image of barchan dune field in coastal Brazil[\/caption]\n\n<span style=\"font-weight: 400\">[pb_glossary id=\"1947\"]Dunes[\/pb_glossary] are complex features formed by a combination of wind direction and sand supply, in some cases interacting with vegetation. There are several types of [pb_glossary id=\"1947\"]dunes[\/pb_glossary] representing variables of wind direction, sand supply and vegetative anchoring. <\/span><b>Barchan [pb_glossary id=\"1947\"]dunes[\/pb_glossary] <\/b><span style=\"font-weight: 400\">or <\/span><b>crescent [pb_glossary id=\"1947\"]dunes[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> form where sand supply is limited and there is a fairly constant wind direction. Barchans move downwind and develop a crescent shape with wings on either side of a [pb_glossary id=\"1947\"]dune[\/pb_glossary] crest. \u00a0Barchans are known to actually move over homes, even towns.<\/span>\n\n[caption id=\"attachment_3520\" align=\"alignleft\" width=\"227\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory.jpg\"><img class=\"wp-image-831\" title=\"Source: NASA image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-300x200.jpg\" alt=\"Long linear parallel dune ridges that form in the direction of prevailing winds.\" width=\"227\" height=\"151\"><\/a> Satellite image of longitudinal dunes in Egypt[\/caption]\n\n<b>[pb_glossary id=\"1511\"]Longitudinal dunes[\/pb_glossary]\u00a0<\/b><span style=\"font-weight: 400\">or <\/span><b>[pb_glossary id=\"1511\"]linear dunes[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> form where sand supply is greater and the wind blows around a dominant direction, in a back-and-forth manner. \u00a0They may form ridges tens of meters high lined up with the predominant wind directions.<\/span>\n\n[caption id=\"attachment_3521\" align=\"alignright\" width=\"212\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.22_usgs_parabolic_dunes_Cape_Cod.jpg\"><img class=\"wp-image-832\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-300x293.jpg\" alt=\"Parabolic dunes anchored by vegetation such that wind blows out the central part and leaves sand wings pointing back from prevailing wind direction\" width=\"212\" height=\"207\"><\/a> Parabolic dunes, Cape Cod[\/caption]\n\n<b>[pb_glossary id=\"1512\"]Parabolic dunes[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> form where vegetation anchors parts of the sand and unanchored parts [pb_glossary id=\"1503\"]blowout[\/pb_glossary]. \u00a0[pb_glossary id=\"1512\"]Parabolic dune[\/pb_glossary] shape may be similar to barchan [pb_glossary id=\"1947\"]dunes[\/pb_glossary] but usually reversed, and it is determined more by the anchoring vegetation than a strict parabolic form.<\/span>\n\n[caption id=\"attachment_3522\" align=\"alignleft\" width=\"255\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.23_Sahara_Star-dune.jpg\"><img class=\"wp-image-833\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-300x228.jpg\" alt=\"a dune iwth a central peak and many ridges formed by shifting winds\" width=\"255\" height=\"193\"><\/a> Star dune in Sahara[\/caption]\n\n<b>[pb_glossary id=\"1513\"]Star dunes[\/pb_glossary]<\/b><span style=\"font-weight: 400\"> form where the wind direction is variable in all directions. \u00a0Sand supply can range from limited to quite abundant. \u00a0It is the variation in wind direction that forms the star.<\/span>\n\n&nbsp;\n\n&nbsp;\n\n&nbsp;\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"91\"]\n\n[caption id=\"attachment_4729\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.3-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-834\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-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 13.3 via this QR Code.[\/caption]\n<h2><b>13.4 The Great Basin and the Basin and Range<\/b><\/h2>\n[caption id=\"attachment_3523\" align=\"alignright\" width=\"268\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.24_Greatbasinmap.png\"><img class=\"wp-image-835 size-medium\" title=\"By Kmusser \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-268x300.png\" alt=\"Map of the Great Basin occupying Utah west of the Wasatch Mountains, most of Neada, southeast Oregon and esxtending into southern California.\" width=\"268\" height=\"300\"><\/a> The Great Basin[\/caption]\n\n<span style=\"font-weight: 400\">The Great [pb_glossary id=\"508\"]Basin[\/pb_glossary] is the largest area of interior [pb_glossary id=\"2208\"]drainage[\/pb_glossary] in North America, meaning there is no outlet to the ocean and all [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] remains in the [pb_glossary id=\"508\"]basin[\/pb_glossary] or is evaporated. It covers western Utah, most of Nevada, and extends into southeastern California, southern Oregon, and southern Idaho. Because there is not outlet to the ocean, [pb_glossary id=\"2212\"]streams[\/pb_glossary] in the Great [pb_glossary id=\"508\"]Basin[\/pb_glossary]\u00a0 deliver [pb_glossary id=\"2205\"]runoff[\/pb_glossary] to lakes and [pb_glossary id=\"1984\"]playas[\/pb_glossary] within the [pb_glossary id=\"508\"]basin[\/pb_glossary]. A subregion within the Great [pb_glossary id=\"508\"]Basin[\/pb_glossary] is the <strong>[pb_glossary id=\"1514\"]Basin and Range[\/pb_glossary]<\/strong> which extends from the Wasatch Front in Utah west across Nevada to the Sierra Nevada Mountains of California. The basins and ranges referred to in the name are\u00a0<\/span>[pb_glossary id=\"1703\"]horsts[\/pb_glossary]<span style=\"font-weight: 400\"> and <\/span>[pb_glossary id=\"1704\"]grabens[\/pb_glossary], formed by<span style=\"font-weight: 400\">\u00a0[pb_glossary id=\"2148\"]normal fault[\/pb_glossary] blocks from\u00a0crustal [pb_glossary id=\"492\"]extension[\/pb_glossary], as discussed in <a href=\"http:\/\/opengeology.org\/textbook\/2-plate-tectonics\/\">chapter 2<\/a> and <a href=\"http:\/\/opengeology.org\/textbook\/9-crustal-deformation-and-earthquakes\/\">chapter 9<\/a><\/span><span style=\"font-weight: 400\">. The [pb_glossary id=\"1668\"]lithosphere[\/pb_glossary] of the entire area has stretched by a factor of about 2, meaning from end to end, the distance has doubled over the past 30 million years or so. Valleys without outlets form individual basins, each of which is filled with [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] [pb_glossary id=\"1756\"]sediments[\/pb_glossary] leading into [pb_glossary id=\"1984\"]playa[\/pb_glossary] [pb_glossary id=\"1960\"]depositional environments[\/pb_glossary]. During the recent [pb_glossary id=\"747\"]Ice Age[\/pb_glossary], The climate was more humid and while glaciers were forming in some of the mountains, [pb_glossary id=\"746\"]pluvial lakes[\/pb_glossary] formed covering large areas (see <a href=\"http:\/\/opengeology.org\/textbook\/14-glaciers\/#1443_Glacial_Lakes\">chapter 14.4.3<\/a>). During the [pb_glossary id=\"747\"]Ice Age[\/pb_glossary], valleys in much of western Utah and eastern Nevada were covered by Lake Bonneville. As the [pb_glossary id=\"757\"]climate[\/pb_glossary] became arid after the [pb_glossary id=\"747\"]Ice Age[\/pb_glossary], Lake Bonneville dried leaving as a remnant the Great Salt Lake in Utah.<\/span>\n\n[caption id=\"attachment_3524\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/RidgecrestCA.jpg\"><img class=\"wp-image-836 size-medium\" title=\"Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-300x200.jpg\" alt=\"The desert has a small town\" width=\"300\" height=\"200\"><\/a> Typical Basin and Range scene. Ridgecrest, CA sits just east of the southern Sierra Nevada Mountains.[\/caption]\n\n<span style=\"font-weight: 400\">The desert of the [pb_glossary id=\"1514\"]Basin and Range[\/pb_glossary] extends from about 35\u00b0 to near 40\u00b0 and results from a rain shadow effect created by westerly winds from the Pacific rising and cooling over the Sierras becoming depleted of moisture by [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] on the western side. The result is relatively dry air descending across Nevada and western Utah. <\/span>\n\n<span style=\"font-weight: 400\">A journey from the Wasatch Front southwest to the Pacific Ocean will show stages of desert landscape evolution from the [pb_glossary id=\"2143\"]fault[\/pb_glossary] block mountains of Utah with sharp peaks and [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fans at the mouths of canyons, through landscapes in Southern Nevada with [pb_glossary id=\"1504\"]bajadas[\/pb_glossary] along the mountain fronts, to the\u00a0 landscapes in the Mojave Desert of California with subdued [pb_glossary id=\"1505\"]inselbergs[\/pb_glossary] sticking up through a sea of coalesced [pb_glossary id=\"1504\"]bajadas[\/pb_glossary]. These landscapes illustrate the evolutionary stages of desert landscape development.<\/span>\n<h3><span style=\"font-weight: 400\">13.4.1 Desertification<\/span><\/h3>\n[caption id=\"attachment_3525\" align=\"alignright\" width=\"481\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Desertification_map.png\"><img class=\"wp-image-837\" title=\"By USDA employee \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-300x194.png\" alt=\"World map showing desertification vulnerability\" width=\"481\" height=\"311\"><\/a> World map showing desertification vulnerability[\/caption]\n\n<span class=\"TextRun SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">When p<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">reviously arable land<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"> suitable for agriculture<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">transforms\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">into desert, <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">this process is called [pb_glossary id=\"1515\"]desertification[\/pb_glossary].\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">Plants and<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">[pb_glossary id=\"1897\"]humus[\/pb_glossary]-rich\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">[pb_glossary id=\"250\"]soil[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">(<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW105139879 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#524_Soil\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW105139879 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW105139879 BCX0\">) promote\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">[pb_glossary id=\"2207\"]groundwater[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">[pb_glossary id=\"2206\"]infiltration[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">and water retention.\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">When\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">an\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">area\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">becomes more arid due to changing environmental conditions<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">, the plants and\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">[pb_glossary id=\"250\"]soil[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">become <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">less effective in retaining water<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">,<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">creating\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">a<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">[pb_glossary id=\"759\"]positive feedback[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">loop<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0of [pb_glossary id=\"1515\"]desertification[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">. Th<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">is<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"> self-reinforcing loop <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">spirals into increasingly arid conditions and further enlarges\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">the desert<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0regions<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">.\u00a0<\/span><\/span><span class=\"EOP SCXW105139879 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span>\n\n<span class=\"TextRun SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW49940429 BCX0\">[pb_glossary id=\"1515\"]Desertification[\/pb_glossary] may be caused\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">by<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0human\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">activities, such as\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">unsustainable<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">crop cultivation\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">practices<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">overgrazing by\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">livestock, over<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">use<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">ground<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">water<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">, and global [pb_glossary id=\"757\"]climate[\/pb_glossary] change<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">Human-caused d<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">esertification\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">is a serious\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">worldwide\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">problem<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">The\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">world map\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">figure above shows <\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">what\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">areas\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">are most\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">vulnerabl<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">e<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0to<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">[pb_glossary id=\"1515\"]desertification[\/pb_glossary].<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">Note the red and orange areas<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0in the\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">western and midwestern\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">regions of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">United States<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">, which also cover large areas of arable land used for raising food crops and animals.\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">T<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">he\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">creation of the <\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">Dust Bowl\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">in\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">the 1930s\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">(<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW49940429 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#524_Soil\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW49940429 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW49940429 BCX0\">)\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">is a classic example of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">a high-vulnerability region impacted by\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">human<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">-<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">caused<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">[pb_glossary id=\"1515\"]desertification[\/pb_glossary].<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0As demonstrated in the Dust Bowl, c<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">onflict<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">s may arise<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0between\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">agricultural practices<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0and conservation measures<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">M<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">itigat<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">ing<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0[pb_glossary id=\"1515\"]desertification[\/pb_glossary]<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">while allowing\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">farmers to make a survivable living requires public and individual education to create community support<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0and\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">understanding of sustainable agriculture\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">alternatives.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><\/span><span class=\"EOP SCXW49940429 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"92\"]\n\n[caption id=\"attachment_4730\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.4-Did-I-Get-It-QR-Code.png\"><img class=\"size-thumbnail wp-image-838\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-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 13.4 via this QR Code.[\/caption]\n<h3>Summary<\/h3>\nApproximately 30% of Earth\u2019s surface is arid lands, the location of which is determined by [pb_glossary id=\"2450\"]latitude[\/pb_glossary], atmospheric circulation, and terrain. The arid belts between 15<sup>o<\/sup> and 30<sup>o<\/sup> north and south latitudes are produced by descending air masses associated with major cells in the [pb_glossary id=\"1745\"]atmosphere[\/pb_glossary] and include the major deserts like the Sahara in Africa and the Middle East. [pb_glossary id=\"1488\"]Rain shadow deserts[\/pb_glossary] lie behind mountain ranges or long land expanses in zones of prevailing winds like the deserts of western North America, the Atacama of South America, and the Gobi of Asia. Dry descending air also creates the [pb_glossary id=\"1489\"]polar deserts[\/pb_glossary] at the poles.\n\nMajor atmospheric circulation involves the [pb_glossary id=\"1490\"]Hadley cells[\/pb_glossary], midlatitude or Ferrel cells, and the [pb_glossary id=\"1493\"]polar cells[\/pb_glossary] in each hemisphere. Warmed and rising air in the [pb_glossary id=\"1490\"]Hadley cells[\/pb_glossary] rains back on the tropics and moves toward the poles as dryer air. That air meets the dryer equatorward moving air of the Ferrel cells. This dry air descends in the arid zones, called the horse latitudes, to produce the arid belts in each hemisphere. Rotation of the Earth creates the Coriolis Effect that deflects these moving air masses to produce zones of prevailing winds, the [pb_glossary id=\"1494\"]Trade Winds[\/pb_glossary] in the subtropics and the [pb_glossary id=\"1495\"]Westerlies[\/pb_glossary] in the midlatitudes. A combination of [pb_glossary id=\"2450\"]latitude[\/pb_glossary], rain shadow, and cold adjacent ocean currents causes the [pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary] of northern Chile,\u00a0 the driest desert on Earth.\n\n[pb_glossary id=\"1754\"]Weath<span style=\"font-size: 1em\">ering<\/span>[\/pb_glossary]<span style=\"font-size: 1em\"> in deserts takes place just as in other climes only slower because of less water. [pb_glossary id=\"1496\"]Desert varnish[\/pb_glossary] is a [pb_glossary id=\"1754\"]weathering[\/pb_glossary] product unique to desert environments. As in more humid climes, water is the main agent of [pb_glossary id=\"1755\"]erosion[\/pb_glossary] although wind is a notable agent. Large dust storms called [pb_glossary id=\"1497\"]haboobs[\/pb_glossary] transport large amounts of [pb_glossary id=\"1756\"]sediment[\/pb_glossary] that may accumulate in sand seas called [pb_glossary id=\"1508\"]ergs[\/pb_glossary] or finer grained [pb_glossary id=\"1987\"]loess[\/pb_glossary] deposits. Sand transport occurs mainly by [pb_glossary id=\"1498\"]saltation[\/pb_glossary] in which grain to grain impact causes frosting of grain surfaces. Sandblasting by persistent winds produces stones with polished surfaces called [pb_glossary id=\"1502\"]ventifacts[\/pb_glossary] and sculpted [pb_glossary id=\"1023\"]bedrock[\/pb_glossary] features called [pb_glossary id=\"1501\"]yardangs[\/pb_glossary].<\/span>\n\nLandforms produced in desert environments include [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fans, [pb_glossary id=\"1504\"]bajadas[\/pb_glossary], [pb_glossary id=\"1505\"]inselbergs[\/pb_glossary], and [pb_glossary id=\"1984\"]playas[\/pb_glossary]. Windblown sand can accumulate as [pb_glossary id=\"1947\"]dunes[\/pb_glossary]. The forms of [pb_glossary id=\"1947\"]dunes[\/pb_glossary], like barchans, parabolic, longitudinal, and [pb_glossary id=\"1513\"]star dunes[\/pb_glossary], relate to the abundance of sand supply and wind direction as well as presence of vegetation. The internal structure of [pb_glossary id=\"1947\"]dunes[\/pb_glossary] shows [pb_glossary id=\"1509\"]cross bedding[\/pb_glossary]. [pb_glossary id=\"1228\"]Fossil[\/pb_glossary] [pb_glossary id=\"1947\"]dunes[\/pb_glossary] in an ancient desert leave [pb_glossary id=\"1509\"]cross bedding[\/pb_glossary] in places like Zion and Arches national parks in Utah showing shifting wind directions in these ancient environments. [pb_glossary id=\"2211\"]Ephemeral[\/pb_glossary] [pb_glossary id=\"2212\"]streams[\/pb_glossary] in desert regions may carry water only after storms and pose risk of [pb_glossary id=\"1506\"]flash floods[\/pb_glossary].\n\nThe Great [pb_glossary id=\"508\"]Basin[\/pb_glossary] of North America is an enclosed [pb_glossary id=\"508\"]basin[\/pb_glossary] with no [pb_glossary id=\"2208\"]drainage[\/pb_glossary] to the ocean. The only exit for [pb_glossary id=\"1785\"]precipitation[\/pb_glossary] there is by evaporation. Travels in the Great [pb_glossary id=\"508\"]Basin[\/pb_glossary] show stages of development of desert landscapes from [pb_glossary id=\"1984\"]playas[\/pb_glossary] and [pb_glossary id=\"1982\"]alluvial[\/pb_glossary] fans, to [pb_glossary id=\"1504\"]bajadas[\/pb_glossary], to [pb_glossary id=\"1505\"]inselbergs[\/pb_glossary] which are eroded mountains buried in their own erosional debris.\n\nPoor land management can result in dying vegetation and loss of [pb_glossary id=\"250\"]soil[\/pb_glossary] moisture producing an accelerating process of [pb_glossary id=\"1515\"]desertification[\/pb_glossary] in which once productive land is degraded into unproductive desert. This is a serious worldwide problem.\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n[h5p id=\"93\"]\n\n[caption id=\"attachment_4731\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Ch.13-Review-Code.png\"><img class=\"size-thumbnail wp-image-839\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-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 13 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<h2><\/h2>\n<ol>\n \t<li><span style=\"color: #000000\">Bagnold, R. A. 1941. \u201cThe Physics of Blown Sand and Desert Dunes.\u201d <em>Methum, London, UK<\/em>, 265.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Boggs, Sam. 2006. \u201cPrinciples of Sedimentology and Stratigraphy.\u201d Pearson Prentice Hall. <a href=\"http:\/\/agris.fao.org\/agris-search\/search.do?recordID=US201300110702\" target=\"_blank\" rel=\"noopener\">http:\/\/agris.fao.org\/agris-search\/search.do?recordID=US201300110702<\/a>.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Clements, Thomas. 1952. \u201cWind-Blown Rocks and Trails on Little Bonnie Claire Playa, Nye County, Nevada.\u201d <em>Journal of Sedimentary Research<\/em> 22 (3). Society for Sedimentary Geology. <a href=\"http:\/\/archives.datapages.com\/data\/sepm\/journals\/v01-32\/data\/022\/022003\/0182.htm\" target=\"_blank\" rel=\"noopener\">http:\/\/archives.datapages.com\/data\/sepm\/journals\/v01-32\/data\/022\/022003\/0182.htm<\/a>.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Collado, Gonzalo A., Mois\u00e9s A. Valladares, and Marco A. M\u00e9ndez. \u201cHidden Diversity in Spring Snails from the Andean Altiplano, the Second Highest Plateau on Earth, and the Atacama Desert, the Driest Place in the World.\u201d <em>Zoological Studies <\/em>52 (1): 50.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Easterbrook, Don J. 1999. <em>Surface Processes and Landforms<\/em>. Pearson College Division.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Geist, Helmut. 2005. <em>The Causes and Progression of Desertification<\/em>. Ashgate Aldershot.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Grayson, Donald K. 1993. <em>The Desert\u2019s Past: A Natural Prehistory of the Great Basin<\/em>. Smithsonian Inst Pr.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Hadley, Geo. 1735. \u201cConcerning the Cause of the General Trade-Winds: By Geo. Hadley, Esq; FRS.\u201d <em>Philosophical Transactions<\/em> 39 (436-444). The Royal Society: 58\u201362.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Hartley, Adrian J., and Guillermo Chong. 2002. \u201cLate Pliocene Age for the Atacama Desert: Implications for the Desertification of Western South America.\u201d <em>Geology<\/em> 30 (1). geology.gsapubs.org: 43\u201346.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Hedin, Sven Anders. 1903. <em>Central Asia and Tibet<\/em>. Vol. 1. Hurst and Blackett, limited.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Hooke, Roger Leb. 1967. \u201cProcesses on Arid-Region Alluvial Fans.\u201d <em>The Journal of Geology<\/em> 75 (4). journals.uchicago.edu: 438\u201360.<\/span><\/li>\n \t<li><span style=\"color: #000000\">King, Lester C. 1953. \u201cCANONS OF LANDSCAPE EVOLUTION.\u201d <em>Geological Society of America Bulletin<\/em> 64 (7). gsabulletin.gsapubs.org: 721\u201352.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Kletetschka, Gunther, Roger Leb Hooke, Andrew Ryan, George Fercana, Emerald McKinney, and Kristopher P. Schwebler. 2013. \u201cSliding Stones of Racetrack Playa, Death Valley, USA: The Roles of Rock Thermal Conductivity and Fluctuating Water Levels.\u201d <em>Geomorphology <\/em>195 (August). Elsevier: 110\u201317.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Laity, Julie E. 2009. \u201cLandforms, Landscapes, and Processes of Aeolian Erosion.\u201d In <em>Geomorphology of Desert Environments<\/em>, edited by Anthony J. Parsons and Athol D. Abrahams, 597\u2013627. Springer Netherlands.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Littell, Eliakim, and Robert S. Littell. 1846. <em>Littell\u2019s Living Age<\/em>. T.H. Carter &amp; Company.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Livingstone, Ian, and Andrew Warren. 1996. <em>Aeolian Geomorphology: An Introduction<\/em>. Longman.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Muhs, Daniel R., and E. A. Bettis. 2003. \u201cQuaternary Loess-Paleosol Sequences as Examples of Climate-Driven Sedimentary Extremes.\u201d <em>Special Papers-Geological Society of America<\/em>. Boulder, Colo.; Geological Society of America; 1999, 53\u201374.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Norris, Richard D., James M. Norris, Ralph D. Lorenz, Jib Ray, and Brian Jackson. 2014. \u201cSliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion.\u201d <em>PloS One<\/em> 9 (8). journals.plos.org: e105948.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Shao, Yaping. 2008. <em>Physics and Modelling of Wind Erosion<\/em>. Springer Science &amp; Business Media.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Stanley, George M. 1955. \u201cORIGIN OF PLAYA STONE TRACKS, RACETRACK PLAYA, INYO COUNTY, CALIFORNIA.\u201d <em>Geological Society of America Bulletin<\/em> 66 (11). gsabulletin.gsapubs.org: 1329\u201350.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Walker, Alta S. 1996. \u201cDeserts: Geology and Resources.\u201d Government Printing Office. <a href=\"https:\/\/pubs.er.usgs.gov\/publication\/7000004\" target=\"_blank\" rel=\"noopener\">https:\/\/pubs.er.usgs.gov\/publication\/7000004<\/a>.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Wilson, Ian Gordon. 1971. \u201cDesert Sandflow Basins and a Model for the Development of Ergs.\u201d <em>The Geographical Journal<\/em> 137 (2). [Wiley, Royal Geographical Society (with the Institute of British Geographers)]: 180\u201399.<\/span><\/li>\n<\/ol>","rendered":"<figure id=\"attachment_3488\" aria-describedby=\"caption-attachment-3488\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/WS1-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3488 size-large\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/WS1-scaled-1.jpg\" alt=\"The dune is made of white sand\" width=\"1024\" height=\"683\" \/><\/a><figcaption id=\"caption-attachment-3488\" class=\"wp-caption-text\">A playa filled with evaporite minerals (such as gypsum) erodes and forms ripple-covered dunes in White Sands National Monument, New Mexico.<\/figcaption><\/figure>\n<h1><b>13 Deserts<\/b><\/h1>\n<p><b>KEY CONCEPTS<\/b><\/p>\n<p>By the end of this chapter, students should be able to:<\/p>\n<ul>\n<li>Explain the defining characteristic of a desert and distinguish between the three broad categories of deserts<\/li>\n<li>Explain how geographic features, latitude, atmospheric circulation, and Coriolis Effect influence where deserts are located<\/li>\n<li>List the primary desert <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">weathering<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> processes<\/li>\n<li>Identify desert landforms<\/li>\n<li>Explain how desert landforms are formed by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1757\">deposition<\/a><\/li>\n<li>Describe the main types of sand dunes and the conditions that form them<\/li>\n<li>Identify the main features of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1514\">Basin and Range<\/a> desert (United States)<\/li>\n<\/ul>\n<figure id=\"attachment_3489\" aria-describedby=\"caption-attachment-3489\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Koppen_World_Map_BWh.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-798 size-medium\" title=\"Peel, M. C., Finlayson, B. L., and McMahon, T. A. (University of Melbourne)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-300x184.png\" alt=\"The hot deserts are all near 30 north or south latitude.\" width=\"300\" height=\"184\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-300x184.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-1024x627.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-768x470.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-1536x941.png 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-65x40.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-225x138.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh-350x214.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Koppen_World_Map_BWh.png 1600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3489\" class=\"wp-caption-text\">World hot deserts (Koppen BWh)<\/figcaption><\/figure>\n<p>Approximately 30% of the Earth\u2019s terrestrial surface consists of deserts, which are defined as locations of low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a>. While <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1767\">temperature<\/a> extremes are often associated with deserts, they do not define them. Deserts exhibit extreme temperatures because of the lack of moisture in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1745\">atmosphere<\/a>, including low humidity and scarce cloud cover. Without cloud cover, the Earth\u2019s surface absorbs more of the Sun\u2019s energy during the day and emits more heat at night.<\/p>\n<figure id=\"attachment_3490\" aria-describedby=\"caption-attachment-3490\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Rainshadow.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-799 size-medium\" title=\"By en:User:Bariot\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-300x169.jpg\" alt=\"There is a dry and wet side to the mountain due to air movement.\" width=\"300\" height=\"169\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-300x169.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-65x37.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-225x127.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow-350x198.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rainshadow.jpg 542w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3490\" class=\"wp-caption-text\">Mountainous areas in front of the prevailing winds create a rain shadow.<\/figcaption><\/figure>\n<p>Deserts are not randomly located on the Earth\u2019s surface. Many deserts are located at latitudes between 15\u00b0 and 30\u00b0 in both hemispheres and at both the North and South Poles, created by prevailing wind circulation in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1745\">atmosphere<\/a>. Sinking, dry air currents occurring at 30\u00b0 north and south of the equator produce <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">trade winds<\/a><\/strong> that create deserts like the African Sahara and Australian Outback.<\/p>\n<figure id=\"attachment_3491\" aria-describedby=\"caption-attachment-3491\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/OwensLake.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-800 size-medium\" title=\"By Picture prepared for Wikipedia by Adrian Pingstone in November 2003. (NASA)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-300x300.jpg\" alt=\"There are several ranges, some more snowy than others.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/OwensLake.jpg 750w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3491\" class=\"wp-caption-text\">In this image from the ISS, the Sierra Nevada Mountains are perpendicular to prevailing westerly winds, creating a rain shadow to the east (down in the image). Note the dramatic decrease in snow on the Inyo Mountains.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Another type of desert is found in the <strong>rain shadow<\/strong> created from prevailing winds blowing over mountain ranges. As the wind drives air up and over mountains, atmospheric moisture is released as snow or rain. Atmospheric pressure is lower at higher elevations, causing the moisture-laden air to cool.\u00a0 Cool air holds less moisture than hot air, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> occurs as the wind rises up the mountain. After releasing its moisture on the windward side of the mountains, the dry air descends on the leeward or downwind side of the mountains to create an arid region with little <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> called a rain shadow.\u00a0 <\/span>Examples of rain-shadow deserts include the Western Interior Desert of North America and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama Desert<\/a> of Chile, which is the Earth\u2019s driest, warm desert.<\/p>\n<p>Finally, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1489\">polar deserts<\/a>, such as vast areas of the Antarctic and Arctic, are created from sinking cold air that is too cold to hold much moisture. Although they are covered with ice and snow, these deserts have very low average annual <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a>. As a result, Antarctica is Earth\u2019s driest <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1653\">continent<\/a>.<\/p>\n<figure id=\"attachment_4732\" aria-describedby=\"caption-attachment-4732\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Rain-Shadow-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-801 size-thumbnail\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Rain-Shadow-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4732\" 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=\"Rain Shadow\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/iMu4dShS74w?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<h2><span style=\"font-weight: 400\"> 13.1 The Origin of Deserts<\/span><\/h2>\n<h3><b>13.1.1 Atmospheric circulation<\/b><\/h3>\n<p>Geographic location, atmospheric circulation, and the Earth\u2019s rotation are the primary causal factors of deserts. Solar energy converted to heat is the engine that drives the circulation of air in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1745\">atmosphere<\/a> and water in the oceans. The strength of the circulation is determined by how much energy is absorbed by the Earth\u2019s surface, which in turn is dependent on the average position of the Sun relative to the Earth. In other words, the Earth is heated unevenly depending on latitude and angle of incidence. Latitude is a line circling the Earth parallel to the equator and is measured in degrees. The equator is 0\u00b0 and the North and South Poles are 90\u00b0 N and 90\u00b0 S respectively (see the diagram of generalized atmospheric circulation on Earth). Angle of incidence is the angle made by a ray of sunlight shining on the Earth\u2019s surface. Tropical zones are located near the equator, where the latitude and angle of incidence are close to 0\u00b0, and receive high amounts of solar energy. The poles, which have latitudes and angles of incidence approaching 90\u00b0, receive little or almost no energy.<\/p>\n<figure id=\"attachment_3492\" aria-describedby=\"caption-attachment-3492\" style=\"width: 500px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/01-Earth_Global_Circulation.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-802\" title=\"This file is in the public domain in the United States because it was solely created by NASA.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation.jpg\" alt=\"An illustration of the earth with three generalized circulation cells shown for each hemisphere.\" width=\"500\" height=\"429\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation.jpg 556w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation-300x257.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation-65x56.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation-225x193.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/01-Earth_Global_Circulation-350x300.jpg 350w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><figcaption id=\"caption-attachment-3492\" class=\"wp-caption-text\">Generalized atmospheric circlustion<\/figcaption><\/figure>\n<p>The figure shows the generalized air circulation within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1745\">atmosphere<\/a>. Three cells of circulating air span the space between the equator and poles in both hemispheres, the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley Cell<\/a><\/strong>, the <strong>Ferrel<\/strong> or <strong>Midlatitude Cell,<\/strong> and the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1493\">Polar Cell<\/a><\/strong>. In the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley Cell<\/a> located over the tropics and closest to the equatorial belt, the sun heats the air and causes it to rise. The rising air cools and releases its contained moisture as tropical rain. The rising dried air spreads away from the equator and toward the north and south poles, where it collides with dry air in the Ferrel Cell. The combined dry air sinks back to the Earth at 30\u00b0 latitude. This sinking drier air creates belts of predominantly high pressure at approximately 30\u00b0 north and south of the equator, called the horse latitudes.\u00a0 Arid zones between 15<sup>o<\/sup> and 30<sup>o<\/sup> north and south of the equator thus exist within which desert conditions predominate. The descending air flowing north and south in the Hadley and Ferrel cells also creates prevailing winds called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">trade winds<\/a> near the equator, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1495\">westerlies<\/a> in the temperate zone. Note the arrows indicating general directions of winds in these zones.<\/p>\n<figure id=\"attachment_3493\" aria-describedby=\"caption-attachment-3493\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Central_Basin_and_Range_ecoregion.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-803 size-medium\" title=\"By C.E. Soulard, USGS\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion-300x264.png\" alt=\"The area covers most of Nevada, easternmost California, southern Idaho, and western Utah.\" width=\"300\" height=\"264\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion-300x264.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion-65x57.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion-225x198.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Central_Basin_and_Range_ecoregion.png 310w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3493\" class=\"wp-caption-text\">USGS Map of the Great Basin Desert.<\/figcaption><\/figure>\n<p>Other deserts, like the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1491\">Great Basin Desert<\/a><\/strong> that covers parts of Utah and Nevada, owe at least part of their origin to other atmospheric phenomena. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1491\">Great Basin Desert<\/a>, while somewhat affected by sinking air effects from global circulation, is a rain-shadow desert. As westerly moist air from the Pacific rises over the Sierra Nevada and other mountains, it cools and loses moisture as condensation and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> on the upwind or rainy side of the mountains.<\/p>\n<figure id=\"attachment_3494\" aria-describedby=\"caption-attachment-3494\" style=\"width: 214px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Atacama_map.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-804 size-medium\" title=\"By cobaltcigs\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-214x300.png\" alt=\"It is in west-central South America\" width=\"214\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-214x300.png 214w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-65x91.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-225x315.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_-350x490.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Atacama_map.svg_.png 434w\" sizes=\"auto, (max-width: 214px) 100vw, 214px\" \/><\/a><figcaption id=\"caption-attachment-3494\" class=\"wp-caption-text\">Map of the Atacama desert (yellow) and surrounding related climate areas (orange).<\/figcaption><\/figure>\n<p>One of the driest places on Earth is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama Desert<\/a><\/strong> of northern Chile. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama Desert<\/a> occupies a strip of land along Chile\u2019s coast just north of latitude 30\u00b0S, at the southern edge of the trade-wind belt. The desert lies west of the Andes Mountains, in the rain shadow created by prevailing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">trade winds<\/a> blowing west. As this warm moist air crossing the Amazon <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">basin<\/a> meets the eastern edge of the mountains, it rises, cools, and precipitates much of its water out as rain. Once over the mountains, the cool, dry air descends onto the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama desert<\/a>.\u00a0 Onshore winds from the Pacific are cooled by the Peru (Humboldt) ocean current. This super-cooled air holds almost no moisture and, with these three factors, some locations in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama Desert<\/a> have received no measured <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> for several years. This desert is the driest, non-polar location on Earth.<\/p>\n<figure id=\"attachment_3495\" aria-describedby=\"caption-attachment-3495\" style=\"width: 277px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/polar_vortex.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-805 size-medium\" title=\"By National Oceanic and Atmospheric Administration - Pacific Marine Environmental Laboratory\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-277x300.jpg\" alt=\"The sinking air is centered just north of Greenland, close to the north pole.\" width=\"277\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-277x300.jpg 277w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-65x70.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-225x244.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex-350x379.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/polar_vortex.jpg 636w\" sizes=\"auto, (max-width: 277px) 100vw, 277px\" \/><\/a><figcaption id=\"caption-attachment-3495\" class=\"wp-caption-text\">The polar vortex of mid-November, 2013. This cold, descending air (shown in purple) is characteristic of polar circulation.<\/figcaption><\/figure>\n<p>Notice in the figure that the polar regions are also areas of predominantly high pressure created by descending cold dry air, the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1493\">Polar Cells<\/a><\/strong>. As with the other cells, cold air, which holds much less moisture than warm air, descends to create <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1489\">polar deserts<\/a>. This is why historically, land near the north and south poles has always been so dry.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><b>13.1.2 Coriolis Effect<\/b><\/h3>\n<figure id=\"attachment_3496\" aria-describedby=\"caption-attachment-3496\" style=\"width: 200px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.2_Corioliskraftanimation.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-806 size-full\" title=\"By Hubi\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2_Corioliskraftanimation.gif\" alt=\"Animation illustrating a ball thrown on a rotating disc. Viewed from the perspective of a stationary viewer on the disc, it appears to follow a curved path.\" width=\"200\" height=\"283\" \/><\/a><figcaption id=\"caption-attachment-3496\" class=\"wp-caption-text\">In the inertial frame of reference of the top picture, the ball moves in a straight line. The observer, represented as a red dot, standing in the rotating frame of reference sees the ball following a curved path. This perceived curvature is due to the Coriolis Effect and centrifugal forces.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>The Earth rotates toward the east where the sun rises. Think of spinning a weight on a string around your head. The speed of the weight depends on the length of the string. The speed of an object on the rotating Earth depends on its horizontal distance from the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_503\">axis<\/a> of rotation. Higher latitudes are a smaller distance from the Earth\u2019s rotational <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_503\">axis<\/a>, and therefore do not travel as fast eastward as lower latitudes that are closer to the equator. When a fluid like air or water moves from a lower latitude to a higher latitude, the fluid maintains its momentum from moving at a higher speed, so it will travel relatively faster eastward than the Earth beneath at the higher latitudes. This factor causes deflection of movements that occur in north-south directions.<\/p>\n<figure id=\"attachment_3497\" aria-describedby=\"caption-attachment-3497\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Coriolis-Effect-E-W.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-807 size-medium\" title=\"From L. Cameron Mosher\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-300x204.jpg\" alt=\"Effect of gravity and the centripetal force to produce the Coriolis Effect on an E-W moving mass on the rotating Earth\" width=\"300\" height=\"204\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-300x204.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-65x44.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-225x153.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W-350x238.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Coriolis-Effect-E-W.jpg 617w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3497\" class=\"wp-caption-text\">Forces ting on a mass moving East-West on the rotating Earth that produce the Coriolis Effect<\/figcaption><\/figure>\n<p>Another factor in the Coriolis effect also causes deflection of east-west movement due to the angle between the centripetal effect of Earth\u2019s spin and gravity pulling toward the earth\u2019s center (see figure). This produces a net deflection toward the equator. The total Coriolis deflection on a mass moving in any direction on the rotating Earth results from a combination of these two factors.<\/p>\n<p>Since each hemisphere has three atmospheric cells moving respectively north and south relative to the Earth beneath them, the Coriolis effect deflects these moving air masses to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The Coriolis effect also deflects moving masses of water in the ocean currents.<\/p>\n<p>For example, in the northern hemisphere <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley Cell<\/a>, the lower altitude air currents are flowing south towards the equator. These are deflected to the right (or west) by the Coriolis effect. This deflected air generates the prevailing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">trade winds<\/a> that European sailors used to cross the Atlantic Ocean and reach South America and the Caribbean Islands in their tall ships. This air movement is mirrored in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley Cell<\/a> in the southern hemisphere; the lower altitude air current flowing equatorward is deflected to the left, creating <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">trade winds<\/a> that blow to the northwest.<\/p>\n<figure id=\"attachment_3498\" aria-describedby=\"caption-attachment-3498\" style=\"width: 256px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.3_Coriolis_effect14.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-808 size-full\" title=\"Used by permission of Anders Persson under under the terms of the GNU Free Documentation License.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14.png\" alt=\"Illustration of the Earth with circles showing the Coriolis deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.\" width=\"256\" height=\"256\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14.png 256w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3_Coriolis_effect14-225x225.png 225w\" sizes=\"auto, (max-width: 256px) 100vw, 256px\" \/><\/a><figcaption id=\"caption-attachment-3498\" class=\"wp-caption-text\">Inertia of air masses caused by the Coriolis Effect in the absence of other forces<\/figcaption><\/figure>\n<p>In the northern Mid-Latitude or Ferrel Cell, surface air currents flow from the horse latitudes (latitude 30\u00b0) toward the North Pole, and the Coriolis effect deflects them toward the east, or to the right, producing the zone of westerly winds. In the southern hemisphere Mid-Latitude or Ferrel Cell, the poleward flowing surface air is deflected to the left and flows southeast creating the Southern Hemisphere <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1495\">westerlies<\/a>.<\/p>\n<p>Another Coriolis-generated deflection produces the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1493\">Polar Cells<\/a>. At 60<sup>o<\/sup> north and south latitude, relatively warmer rising air\u00a0 flows poleward cooling and converging at the poles where it sinks in the polar high. This sinking dry air creates the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1493\">polar deserts<\/a>, the driest deserts on Earth. Persistence of ice and snow is a result of cold temperatures at these dry locations.<\/p>\n<figure id=\"attachment_3499\" aria-describedby=\"caption-attachment-3499\" style=\"width: 393px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.4_Corrientes-oceanicas.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-809\" title=\"This work is in the public domain in the United States\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-300x157.png\" alt=\"Warm currents are red, blue currents are blue.\" width=\"393\" height=\"205\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-300x157.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-768x401.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-65x34.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-225x117.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas-350x183.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4_Corrientes-oceanicas.png 1000w\" sizes=\"auto, (max-width: 393px) 100vw, 393px\" \/><\/a><figcaption id=\"caption-attachment-3499\" class=\"wp-caption-text\">Gyres of the Earth\u2019s oceans.<\/figcaption><\/figure>\n<p>The Coriolis effect operates on all motions on the Earth. Artillerymen must take the Coriolis effect into account on ballistic trajectories when making long-distance targeting calculations. Geologists note how its effect on air and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1659\">oceanic<\/a> currents creates deserts in designated zones around the Earth as well as the surface currents in the ocean. The Coriolis effect causes the ocean <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1478\">gyres<\/a> to turn clockwise in the northern hemisphere and counterclockwise in the southern. It also affects <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_756\">weather<\/a> by creating high-altitude, polar jet streams that sometimes push lobes of cold arctic air into the temperate zone, down to as far as latitude 30\u00b0 from the usual 60\u00b0. It also causes low pressure systems and intense tropical storms to rotate counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.<\/p>\n<figure id=\"attachment_4733\" aria-describedby=\"caption-attachment-4733\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/The-Coriolis-Effect-Explained-Youtube-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-810\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The-Coriolis-Effect-Explained-Youtube-QR-Code.png 1155w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4733\" 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>&nbsp;<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"The Coriolis Effect Explained\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/HIyBpi7B-dE?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><em><span style=\"font-size: 10pt\">Explanation of Coriolis Effect.<\/span><\/em><\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-89\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-89\" class=\"h5p-iframe\" data-content-id=\"89\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4727\" aria-describedby=\"caption-attachment-4727\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.1-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-811\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.1-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4727\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section13.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">13.2 Desert weathering and erosion<\/span><\/h2>\n<figure id=\"attachment_3500\" aria-describedby=\"caption-attachment-3500\" style=\"width: 360px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/CNL9-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3500\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/CNL9-scaled-1.jpg\" alt=\"There is an arch and spires\" width=\"360\" height=\"308\" \/><\/a><figcaption id=\"caption-attachment-3500\" class=\"wp-caption-text\">Weathering and erosion of Canyonlands National Park has created a unique landscape, including arches, cliffs, and spires.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">Weathering<\/a> takes place in desert climates by the same means as other climates, only at a slower rate. While higher temperatures typically spur faster chemical weathering, water is the main agent of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">weathering<\/a>, and lack of water slows both mechanical and chemical weathering. <span class=\"NormalTextRun SCXW70160266 BCX0\">Low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> levels also mean less <\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">runoff<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">as well as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_254\">ice wedging<\/a><\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">.<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0W<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">hen<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a><\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">does occur<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">\u00a0in the desert, it is\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">often\u00a0<\/span><span class=\"NormalTextRun SCXW70160266 BCX0\">heavy and may result in<\/span> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1506\">flash floods<\/a> in which a lot of material may be dislodged and moved quickly.<\/span><\/p>\n<figure id=\"attachment_3501\" aria-describedby=\"caption-attachment-3501\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Newspaper_Rock_Full.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-813 size-medium\" title=\"By Cacophony\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-300x200.jpg\" alt=\"The rock is dark brown with petroglyphs\" width=\"300\" height=\"200\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-1024x683.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-768x512.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-1536x1024.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full-350x233.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Newspaper_Rock_Full.jpg 1599w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3501\" class=\"wp-caption-text\">Newspaper rock, near Canyonlands National Park, has many petroglyphs carved into desert varnish.<\/figcaption><\/figure>\n<p>One unique <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">weathering<\/a> product in deserts is <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1496\">desert varnish<\/a><\/strong>. Also known as desert patina or rock rust, this is thin dark brown layers of clay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1765\">minerals<\/a> and iron and manganese <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_971\">oxides<\/a> that form on very stable surfaces within arid environments. The exact way this material forms is still unknown, though cosmogenic and biologic mechanisms have been proposed.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_3502\" aria-describedby=\"caption-attachment-3502\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/MN7.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-814 size-medium\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-300x225.jpg\" alt=\"The left of the picture is full of brown dust\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-1536x1152.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/MN7.jpg 2048w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3502\" class=\"wp-caption-text\">A dust storm (haboob) hits the Mongolian Gobi.<\/figcaption><\/figure>\n<p>While water is still the dominant agent of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> in most desert environments, wind is a notable agent of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">weathering<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> in many\u00a0deserts. This includes suspended <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1756\">sediment<\/a> traveling in\u00a0<strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1497\">haboobs<\/a><\/strong>, or large dust storms, that frequent deserts. Deposits of windblown dust are called <b>loess<\/b>. Loess deposits cover wide areas of the midwestern United States, much of it from rock flour that melted out of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1519\">ice sheets<\/a> during the last <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_747\">ice age<\/a>. Loess was also blown from desert regions in the West. Possessing lower energy than water, wind transport nevertheless moves sand, silt, and dust<span style=\"font-weight: 400\">. As noted in <a href=\"http:\/\/opengeology.org\/textbook\/11-water\/\">chapter 11<\/a>, the load carried by a fluid (air is a fluid like water) is distributed among bedload and suspended load. As with water, in wind these components depend on wind velocity<\/span><span style=\"font-weight: 400\">.<\/span><span style=\"font-weight: 400\">\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.5_Saltation-mechanics.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright wp-image-815 size-full\" title=\"By NASA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.5_Saltation-mechanics.gif\" alt=\"Sand grains bouncing and splashing out other grains in saltation.\" width=\"270\" height=\"176\" \/><\/a>Sand size material moves by a process called <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1498\">saltation<\/a><\/b><span style=\"font-weight: 400\"> in which sand grains are lifted into the moving air and carried a short distance where they drop and splash into the surface dislodging other sand grains which are then carried a short distance and splash dislodging still others<\/span><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3504\" aria-describedby=\"caption-attachment-3504\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-364 size-medium\" title=\"Photo by Mark A. Wilson and released into the Public domain.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg\" alt=\"Windblown sand grains showing rounding and frosted surfaces due to transport b wind.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg 1500w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3504\" class=\"wp-caption-text\">Enlarged image of frosted and rounded windblown sand grains<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Since saltating sand grains are constantly impacting other sand grains, wind blown sand grains are commonly quite well rounded with frosted surfaces. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1498\">Saltation<\/a> is a cascading effect of sand movement creating a zone of wind blown sand up to a meter or so above the ground. This zone of saltating sand is a powerful <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosive<\/a> agent in which <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1023\">bedrock<\/a> features are effectively sandblasted. The fine-grained suspended load is effectively sorted from the sand near the surface carrying the silt and dust into <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1497\">haboobs<\/a>. Wind is thus an effective sorting agent separating sand and dust sized (\u226470 \u00b5m) particles <span class=\"TextRun BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW201347767\">(<\/span><\/span><a class=\"Hyperlink BCX0 SCXW201347767\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/%22%20\/l%20%22532_Detrital_Sedimentary_Rocks_Clastic\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"FieldRange BCX0 SCXW201347767\"><span class=\"TextRun Underlined BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun CommentStart BCX0 SCXW201347767\" data-ccp-charstyle=\"Hyperlink\">See Chapter 5<\/span><\/span><\/span><\/a><span class=\"TextRun BCX0 SCXW201347767\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW201347767\">)<\/span><\/span><\/span><span style=\"font-weight: 400\">.\u00a0When wind velocity is high enough to slide or roll materials along the surface, the process is called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1499\">creep<\/a><\/strong>. <\/span><\/p>\n<p><span style=\"font-weight: 400\" data-wp-editing=\"1\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.6_2006_1205_135618-DVNP-RACETRACK.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-816 size-medium\" title=\"Source: This image is used under the terms of the GNU Free Documentation License\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-272x300.jpg\" alt=\"A large rock has slid over the playa surface leaving a track in the mud.\" width=\"272\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-272x300.jpg 272w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-768x846.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-65x72.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-225x248.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK-350x386.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.6_2006_1205_135618-DVNP-RACETRACK.jpg 816w\" sizes=\"auto, (max-width: 272px) 100vw, 272px\" \/><\/a>One extreme version of sediment movement was shrouded in mystery for years: <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1500\">Sliding stones<\/a><\/b><span style=\"font-weight: 400\">. Also called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1500\">sailing stones<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1500\">sliding rocks<\/a>, these are large moving boulders along flat surfaces in deserts, leaving trails. This includes the famous example of the Racetrack Playa in Death Valley National Park, California<\/span><span style=\"font-weight: 400\">. For years, scientists and enthusiasts attempted to explain their movement, with little definitive results<\/span><span style=\"font-weight: 400\">. In recent years, several experimental and observational studies have confirmed that the stones, imbedded in thin layers of ice, are propelled by friction from high winds<\/span><span style=\"font-weight: 400\">. These studies include measurements of actual movement, as well as re-creations of the conditions, with resulting movement in the lab.<\/span><\/p>\n<figure id=\"attachment_3507\" aria-describedby=\"caption-attachment-3507\" style=\"width: 150px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.8_VentifactMojaveDesert031511-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3507 size-thumbnail\" title=\"&quot;Source:\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.8_VentifactMojaveDesert031511-scaled-1.jpg\" alt=\"Rock on desert floor polished on multiple sides by sandblasting.\" width=\"150\" height=\"150\" \/><\/a><figcaption id=\"caption-attachment-3507\" class=\"wp-caption-text\">Ventifact from Mojave Desert near Barstow, CA<\/figcaption><\/figure>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.7_Yardang_Im_Salar_de_Uyuni.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright wp-image-818\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-300x223.jpg\" alt=\"Large rock standing on a base narrowed by sandblasting.\" width=\"202\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-300x223.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-1024x760.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-768x570.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-1536x1140.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-2048x1520.jpg 2048w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-65x48.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-225x167.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.7_Yardang_Im_Salar_de_Uyuni-350x260.jpg 350w\" sizes=\"auto, (max-width: 202px) 100vw, 202px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">The zone of saltating sand is an effective agent of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> through sand abrasion. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1023\">bedrock<\/a> outcrop which has such a sandblasted shape is called a <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1501\">yardang<\/a><\/b><span style=\"font-weight: 400\">. Rocks and boulders lying on the surface may be blasted and polished by saltating sand. When predominant wind directions shift, multiple sandblasted and polished faces may appear. Such wind abraded desert rocks are called <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1502\">ventifacts<\/a><\/b><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3525\" aria-describedby=\"caption-attachment-3525\" style=\"width: 253px\" class=\"wp-caption alignright\"><a href=\"http:\/\/opengeology.org\/textbook\/wp-content\/uploads\/2016\/07\/13.9_Blowout_Earth_TX.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-819\" title=\"Source: This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-300x184.jpg\" alt=\"Photo of land level lowered by wind causing a blowout.\" width=\"253\" height=\"155\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-300x184.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-65x40.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-225x138.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX-350x214.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.9_Blowout_Earth_TX.jpg 608w\" sizes=\"auto, (max-width: 253px) 100vw, 253px\" \/><\/a><figcaption id=\"caption-attachment-3525\" class=\"wp-caption-text\">Blowout in Texas<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">In places with sand and silt accumulations, clumps of vegetation often anchor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1756\">sediment<\/a> on the desert surface. Yet, winds may be sufficient to remove materials not anchored by vegetation. The bowl-shaped depression remaining on the surface is called a <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1503\">blowout<\/a><\/b><span style=\"font-weight: 400\">.<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-90\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-90\" class=\"h5p-iframe\" data-content-id=\"90\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4728\" aria-describedby=\"caption-attachment-4728\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.2-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-820\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.2-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4728\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 13.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">13.3 Desert landforms<\/span><\/h2>\n<figure id=\"attachment_3510\" aria-describedby=\"caption-attachment-3510\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.10_Alluvial_Fan.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-821 size-medium\" title=\"Source: This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-300x158.jpg\" alt=\"Looking down on semi-circular fan-shaped deposit where a stream emerges from a canyon in Death Valley\" width=\"300\" height=\"158\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-300x158.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-1024x541.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-768x405.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-65x34.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-225x119.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan-350x185.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.10_Alluvial_Fan.jpg 1146w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3510\" class=\"wp-caption-text\">Aerial image of alluvial fan in Death Valley<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\"><span class=\"NormalTextRun BCX0 SCXW147497739\">In the American Southwest,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">as\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">streams<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">emerge into the valleys<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0from<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">adjacent\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">mountains<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">, they<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">create desert landforms called alluvial fans<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">. When the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">stream<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">emerges from<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0narrow\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 BCX0 SCXW147497739\">canyon,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0the flow is no longer constrained by the canyon walls<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0and spreads out<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">. At the\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">lower slope angle<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">,<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the water<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">slows down and\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">drops its coarser load<\/span>. As the channel fills with this conglomeratic material, the stream is deflected around it. <span class=\"NormalTextRun BCX0 SCXW147497739\">This\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">deposited material deflects\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">the<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">stream<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">into\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1742\">system<\/a><\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">of radial distributar<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">y channels in a\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">process<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun AdvancedProofingIssueV2 BCX0 SCXW147497739\">similar to<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">how\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">delta<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">is made\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">by a<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">river<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">entering a body of water<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">.<\/span><span class=\"NormalTextRun BCX0 SCXW147497739\">\u00a0<\/span>This process develops a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1742\">system<\/a> of radial distributaries and constructs a fan shaped feature called an <\/span><b>alluvial fan<\/b><b>.\u00a0<\/b><\/p>\n<figure id=\"attachment_3511\" aria-describedby=\"caption-attachment-3511\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.11_Bajada_at_FriscoMountainUT-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3511 size-medium\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.11_Bajada_at_FriscoMountainUT-scaled-1.jpg\" alt=\"Photo of mountain where alluvial fans have coalesced into an apron of sedimant along the mountain front.\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-3511\" class=\"wp-caption-text\">Bajada along Frisco Peak in Utah<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400\">Alluvial fans continue to grow and may eventually coalesce with neighboring fans to form an apron of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1652\">alluvium<\/a> along the mountain front called a <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajada<\/a><\/b><span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3512\" aria-describedby=\"caption-attachment-3512\" style=\"width: 225px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.12_Inselbergs_in_Mojave_Desert.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-823 size-medium\" title=\"Source: Image from USGS\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert-225x300.jpg\" alt=\"Aerial photo of mountain remnants surrounded by their own erosional debris.\" width=\"225\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert-225x300.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert-65x87.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert-350x467.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.12_Inselbergs_in_Mojave_Desert.jpg 500w\" sizes=\"auto, (max-width: 225px) 100vw, 225px\" \/><\/a><figcaption id=\"caption-attachment-3512\" class=\"wp-caption-text\">Inselbergs in Mojave Desert<\/figcaption><\/figure>\n<p>As the mountains erode away and their <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1756\">sediment<\/a> accumulates first in alluvial fans, then <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajadas<\/a>, the mountains eventually are buried in their own erosional debris. Such buried mountain remnants are called <b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1505\">inselbergs<\/a><\/b><span style=\"font-weight: 400\">, \u201cisland mountains,\u201d as first described by the German geologist Wilhelm Bornhardt <span class=\"TextRun BCX0 SCXW36294923\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun BCX0 SCXW36294923\">(1864\u20131946)<\/span><\/span>.<\/span><\/p>\n<figure id=\"attachment_3513\" aria-describedby=\"caption-attachment-3513\" style=\"width: 244px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.14a_dolansprings_oli_2013088_playa_lrg-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3513\" title=\"Satellite image from NASA.\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.14a_dolansprings_oli_2013088_playa_lrg-scaled-1.jpg\" alt=\"Satellite image of desert dry lake or playa surrounded by mountains.\" width=\"244\" height=\"183\" \/><\/a><figcaption id=\"caption-attachment-3513\" class=\"wp-caption-text\">Satellite image of desert playa surrounded by mountains<\/figcaption><\/figure>\n<p>Where the desert valley is an enclosed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">basin<\/a>, i.e. streams entering it do not drain out, the water is removed by evaporation and a dry lake bed is formed called a <b>playa.<\/b><\/p>\n<figure id=\"attachment_3514\" aria-describedby=\"caption-attachment-3514\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.13_Dry_Wash_in_PEFO_NP.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-825 size-medium\" title=\"By Finetooth\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-300x181.jpg\" alt=\"Photo of dry wash that carries water only after rains.\" width=\"300\" height=\"181\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-300x181.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-1024x617.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-768x463.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-65x39.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-225x136.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP-350x211.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.13_Dry_Wash_in_PEFO_NP.jpg 1199w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3514\" class=\"wp-caption-text\">Dry wash (or ephemeral stream)<\/figcaption><\/figure>\n<p>Playas are among the flattest of all landforms. Such a dry lake bed may cover a large area and be filled after a heavy thunderstorm to only a few inches deep. Playa lakes and desert streams that contain water only after rainstorms are called <b>intermittent\u00a0<\/b><span style=\"font-weight: 400\">\u00a0or <\/span><b>ephemeral<\/b><span style=\"font-weight: 400\">. <span class=\"TextRun SCXW175656738 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW175656738 BCX0\">Because of intense thunderstorms, the volume of water transported by ephemeral d<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">rainage<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">in arid environments can be substantial during a short <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1244\">period<\/a> of time. Desert soil structures\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">lack organic matter that<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">promotes <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">infiltration<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">by absorbing water<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">.<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">Instead of percolating into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_250\">soil<\/a>, the runoff\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">compacts the\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">ground\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">surface<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">, making the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_250\">soil<\/a>\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW175656738 BCX0\">hydrophobic<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0or water-repellant<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">. Because of t<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">his <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">hardpan surface, ephemeral streams may <\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">gather water\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">across\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">large areas<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">suddenly fill<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">ing<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\"> with water from storms many miles away<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW175656738 BCX0\">\u00a0<\/span><\/span><span class=\"EOP SCXW175656738 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/span><span style=\"font-weight: 400\">\u00a0\u00a0<\/span><\/p>\n<figure id=\"attachment_3515\" aria-describedby=\"caption-attachment-3515\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.15_Flash_flood_in_the_desert-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-826 size-medium\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-300x225.jpg\" alt=\"Formerly dry wash now a violent torrent after heavy rain in the area\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-1536x1152.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.15_Flash_flood_in_the_desert-1.jpg 1600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3515\" class=\"wp-caption-text\">Flash flood in a dry wash<\/figcaption><\/figure>\n<p><span class=\"TextRun SCXW131970605 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">H<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">igh-volume<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">ephemeral<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0f<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">lows<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, called\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1506\">flash floods<\/a><\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">,<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0may move as sheet flows<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1507\">sheetwash<\/a><\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, as well as\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">be\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">channeled through normally dry arroyos or canyons<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">F<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">lash floods<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">are a major factor in desert<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1757\">deposition<\/a>.<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW131970605 BCX0\">Dry<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">channels\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">can<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">fill quickly<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0with ephemeral drainage<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">, creating<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">a mass of water and debris that charges down\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">the arroyo<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">and\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">even overflowing the banks.<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1506\">Flash floods<\/a> pose\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">a serious\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">hazard\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">for desert travelers\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">because the storm activity feeding the runoff may be <\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">miles away<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">People\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">hiking\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">or camping\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">in arroyos\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">that have been bone dry for months, or years,\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">have been swept away by sudden<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW131970605 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1506\">flash floods<\/a>.<\/span><\/span><span class=\"EOP SCXW131970605 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<h3><b>13.3.1 Sand<\/b><\/h3>\n<figure id=\"attachment_3516\" aria-describedby=\"caption-attachment-3516\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.16_Sahara_Desert_in_Jalu_Libya.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-3516\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.16_Sahara_Desert_in_Jalu_Libya.jpeg\" alt=\"The Sahara Desert, a sea of sand or erg.\" width=\"300\" height=\"225\" \/><\/a><figcaption id=\"caption-attachment-3516\" class=\"wp-caption-text\">Sahara Desert, a sand sea or erg<\/figcaption><\/figure>\n<p><span class=\"TextRun SCXW253049173 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">T<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">he popular concept of a typical desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0is a\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">broad expanse of\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">. Geologically,\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">s<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">are\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">defined by <\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">a lack of water and arid regions resembling a sea of sand belong to the category of desert<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0called an<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><strong><span class=\"NormalTextRun SCXW253049173 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">erg<\/a><\/span><\/strong><span class=\"NormalTextRun SCXW253049173 BCX0\">. An<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">erg<\/a><\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">consists of\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">fine-grained<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, loose<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0grains,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">often blown by<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">wind, or\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">aeolian<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">forces<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0into<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">dunes. Probably the\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">best known<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">erg<\/a><\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">is the\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">Rub\u2019 al Khali<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, which means\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Empty Quarter<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">of\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Arabia<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">n Peninsula.<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">E<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">rgs<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">are also found in<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Great Sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Dunes<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">National Park<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Colorado<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">)<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, Little Sahara Recreation Area<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Utah<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">), White Sands National Monument<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">New Mexico<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">), and parts of Death Valley National Park<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0(<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">California<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">).\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">Ergs<\/a> are not restricted to\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">deserts<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, but may\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">form<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">anywhere\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">the<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">re<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">is a\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW253049173 BCX0\">substantial\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">supply\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">of sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, including as\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">far north as 60\u00b0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0N\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">in Saskatchewan<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">,<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Canada, in the\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Athabasca Sand<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Dunes<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">Provincial\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">Park<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun ContextualSpellingAndGrammarErrorV2 SCXW253049173 BCX0\">.<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0Coastal<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">ergs<\/a><\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">exist along\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">lakes and oceans<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">\u00a0as well<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">, and\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">examples are\u00a0<\/span><span class=\"NormalTextRun SCXW253049173 BCX0\">found in Oregon, Michigan, and Indiana.<\/span><\/span><span class=\"EOP SCXW253049173 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.17_Formation-of-cross_beds.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-full wp-image-828\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.17_Formation-of-cross_beds.gif\" alt=\"Illustrating the formation of\" width=\"290\" height=\"74\" \/><\/a>An internal cross section of a sand dune shows a feature called <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1509\">cross bedding<\/a><\/b><span style=\"font-weight: 400\">. As wind blows up the windward side of the dune, it carries sand to the dune crest depositing layers of sand parallel to the windward (or \u201cstoss\u201d) side. The sand builds up the crest of the dune and pours over the top until the leeward (downwind or slip) face of the dune reaches the <\/span><b>angle of repose,\u00a0<\/b><span style=\"font-weight: 400\">the maximum angle which will support the slip face. Dunes are unstable features and move as the sand erodes from the stoss side and continues to drop down the leeward side covering previous stoss and slip-face layers and creating the cross beds. Mostly, these are reworked over and over again, but occasionally, the features are preserved in a depression, then lithified. Shifting wind directions and abundant sand sources create chaotic patterns of cross beds like those seen in Zion National Park of Utah.\u00a0<\/span><\/p>\n<figure id=\"attachment_3518\" aria-describedby=\"caption-attachment-3518\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.18_Sandstone_showing_Cross-bedding_Zion_National_Park_Utah_USA-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-3518\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.18_Sandstone_showing_Cross-bedding_Zion_National_Park_Utah_USA-scaled-1.jpg\" alt=\"Image of cross bedding in ancient sand dunes at Zion National Park, Utah.\" width=\"300\" height=\"200\" \/><\/a><figcaption id=\"caption-attachment-3518\" class=\"wp-caption-text\">Cross beds in the Navajo Sandstone at Zion National Park<\/figcaption><\/figure>\n<p><span class=\"TextRun SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW213184174 BCX0\">In the<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_479\">Mesozoic<\/a><\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1243\">Era<\/a><\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">, Utah was covered by a series of<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">ergs<\/a>,\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">with\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">thickest\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">being\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">in Southern Utah<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">which lithified into sandstone (<\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW213184174 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#531_Lithification_and_Diagenesis\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW213184174 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW213184174 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW213184174 BCX0\">)<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">. Perhaps the best known of these<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">sandstone<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">formations<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">is the Navajo<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Sandstone of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_486\">Jurassic<\/a> age. This <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">sandstone\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">form<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">ation<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">consists of\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">dramatic cliffs and spires in Zion National Park and covers a large part of the Colorado Plateau.\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">In\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Arches National Park, a later series of sand<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">dunes<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">covered the Navajo Sandstone and lithified to become the Entrada Formation also during the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_486\">Jurassic<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">Erosion<\/a> of overlying layers <\/span><span class=\"NormalTextRun CommentStart SCXW213184174 BCX0\">exposed fins of <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">the underlying\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Entrada<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">Sandstone<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">\u00a0and\u00a0<\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">carved out weaker parts of the fins forming the <\/span><span class=\"NormalTextRun SCXW213184174 BCX0\">arches.<\/span><\/span><span class=\"EOP SCXW213184174 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<figure id=\"attachment_3504\" aria-describedby=\"caption-attachment-3504\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-364\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg\" alt=\"Windblown sand grains showing rounding and frosted surfaces due to transport b wind.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.19_Windblown_sand_grains_CoralPinkSandDunesSand-1.jpg 1500w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3504\" class=\"wp-caption-text\">Enlarged image of frosted and rounded windblown sand grains<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">As the cements that hold the grains together in these modern sand cliffs disintegrate and the freed grains gather at the base of the cliffs and move down the washes, sand grains may be recycled and redeposited. These <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_479\">Mesozoic<\/a> sand <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">ergs<\/a> may represent ancient <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_967\">quartz<\/a> sands recycled many times from <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1753\">igneous<\/a> origins in the early <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1270\">Precambrian<\/a>, just passing now through another cycle of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1757\">deposition<\/a>. <\/span><span style=\"font-weight: 400\">An example of this is Coral Pink Sand Dunes State Park in Southwestern Utah, which contains sand that is being eroded from the Navajo Sandstone to form new dunes.<\/span><\/p>\n<h4><b>Dune Types<\/b><\/h4>\n<figure id=\"attachment_3519\" aria-describedby=\"caption-attachment-3519\" style=\"width: 190px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.20a_Barchan_dune_field_coastal_Brazil.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-830\" title=\"Source: NASA image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-300x300.jpg\" alt=\"Satellite image of a field of bnarchan dunes, eqach showing the fcharacteristic shape of sand wings wrapped around the bare dune court. The wionmgs point in the direction of prevailing winds.\" width=\"190\" height=\"190\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.20a_Barchan_dune_field_coastal_Brazil.jpg 540w\" sizes=\"auto, (max-width: 190px) 100vw, 190px\" \/><\/a><figcaption id=\"caption-attachment-3519\" class=\"wp-caption-text\">NASA image of barchan dune field in coastal Brazil<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">Dunes are complex features formed by a combination of wind direction and sand supply, in some cases interacting with vegetation. There are several types of dunes representing variables of wind direction, sand supply and vegetative anchoring. <\/span><b>Barchan dunes <\/b><span style=\"font-weight: 400\">or <\/span><b>crescent dunes<\/b><span style=\"font-weight: 400\"> form where sand supply is limited and there is a fairly constant wind direction. Barchans move downwind and develop a crescent shape with wings on either side of a dune crest. \u00a0Barchans are known to actually move over homes, even towns.<\/span><\/p>\n<figure id=\"attachment_3520\" aria-describedby=\"caption-attachment-3520\" style=\"width: 227px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-831\" title=\"Source: NASA image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-300x200.jpg\" alt=\"Long linear parallel dune ridges that form in the direction of prevailing winds.\" width=\"227\" height=\"151\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory-350x233.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Linear_Dunes_Great_Sand_Sea_Egypt_-_NASA_Earth_Observatory.jpg 720w\" sizes=\"auto, (max-width: 227px) 100vw, 227px\" \/><\/a><figcaption id=\"caption-attachment-3520\" class=\"wp-caption-text\">Satellite image of longitudinal dunes in Egypt<\/figcaption><\/figure>\n<p><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1511\">Longitudinal dunes<\/a>\u00a0<\/b><span style=\"font-weight: 400\">or <\/span><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1511\">linear dunes<\/a><\/b><span style=\"font-weight: 400\"> form where sand supply is greater and the wind blows around a dominant direction, in a back-and-forth manner. \u00a0They may form ridges tens of meters high lined up with the predominant wind directions.<\/span><\/p>\n<figure id=\"attachment_3521\" aria-describedby=\"caption-attachment-3521\" style=\"width: 212px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.22_usgs_parabolic_dunes_Cape_Cod.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-832\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-300x293.jpg\" alt=\"Parabolic dunes anchored by vegetation such that wind blows out the central part and leaves sand wings pointing back from prevailing wind direction\" width=\"212\" height=\"207\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-300x293.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-65x63.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-225x219.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod-350x341.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.22_usgs_parabolic_dunes_Cape_Cod.jpg 400w\" sizes=\"auto, (max-width: 212px) 100vw, 212px\" \/><\/a><figcaption id=\"caption-attachment-3521\" class=\"wp-caption-text\">Parabolic dunes, Cape Cod<\/figcaption><\/figure>\n<p><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1512\">Parabolic dunes<\/a><\/b><span style=\"font-weight: 400\"> form where vegetation anchors parts of the sand and unanchored parts <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1503\">blowout<\/a>. \u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1512\">Parabolic dune<\/a> shape may be similar to barchan dunes but usually reversed, and it is determined more by the anchoring vegetation than a strict parabolic form.<\/span><\/p>\n<figure id=\"attachment_3522\" aria-describedby=\"caption-attachment-3522\" style=\"width: 255px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.23_Sahara_Star-dune.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-833\" title=\"Source: USGS image in the Public Domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-300x228.jpg\" alt=\"a dune iwth a central peak and many ridges formed by shifting winds\" width=\"255\" height=\"193\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-300x228.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-1024x777.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-768x582.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-225x171.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune-350x265.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.23_Sahara_Star-dune.jpg 1341w\" sizes=\"auto, (max-width: 255px) 100vw, 255px\" \/><\/a><figcaption id=\"caption-attachment-3522\" class=\"wp-caption-text\">Star dune in Sahara<\/figcaption><\/figure>\n<p><b><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1513\">Star dunes<\/a><\/b><span style=\"font-weight: 400\"> form where the wind direction is variable in all directions. \u00a0Sand supply can range from limited to quite abundant. \u00a0It is the variation in wind direction that forms the star.<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-91\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-91\" class=\"h5p-iframe\" data-content-id=\"91\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4729\" aria-describedby=\"caption-attachment-4729\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.3-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-834\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.3-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4729\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 13.3 via this QR Code.<\/figcaption><\/figure>\n<h2><b>13.4 The Great Basin and the Basin and Range<\/b><\/h2>\n<figure id=\"attachment_3523\" aria-describedby=\"caption-attachment-3523\" style=\"width: 268px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/13.24_Greatbasinmap.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-835 size-medium\" title=\"By Kmusser\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-268x300.png\" alt=\"Map of the Great Basin occupying Utah west of the Wasatch Mountains, most of Neada, southeast Oregon and esxtending into southern California.\" width=\"268\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-268x300.png 268w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-916x1024.png 916w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-768x858.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-1375x1536.png 1375w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-65x73.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-225x251.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap-350x391.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.24_Greatbasinmap.png 1500w\" sizes=\"auto, (max-width: 268px) 100vw, 268px\" \/><\/a><figcaption id=\"caption-attachment-3523\" class=\"wp-caption-text\">The Great Basin<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">Basin<\/a> is the largest area of interior drainage in North America, meaning there is no outlet to the ocean and all <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> remains in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">basin<\/a> or is evaporated. It covers western Utah, most of Nevada, and extends into southeastern California, southern Oregon, and southern Idaho. Because there is not outlet to the ocean, streams in the Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">Basin<\/a>\u00a0 deliver runoff to lakes and playas within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">basin<\/a>. A subregion within the Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">Basin<\/a> is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1514\">Basin and Range<\/a><\/strong> which extends from the Wasatch Front in Utah west across Nevada to the Sierra Nevada Mountains of California. The basins and ranges referred to in the name are\u00a0<\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1703\">horsts<\/a><span style=\"font-weight: 400\"> and <\/span><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1704\">grabens<\/a>, formed by<span style=\"font-weight: 400\">\u00a0normal fault blocks from\u00a0crustal <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_492\">extension<\/a>, as discussed in <a href=\"http:\/\/opengeology.org\/textbook\/2-plate-tectonics\/\">chapter 2<\/a> and <a href=\"http:\/\/opengeology.org\/textbook\/9-crustal-deformation-and-earthquakes\/\">chapter 9<\/a><\/span><span style=\"font-weight: 400\">. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1668\">lithosphere<\/a> of the entire area has stretched by a factor of about 2, meaning from end to end, the distance has doubled over the past 30 million years or so. Valleys without outlets form individual basins, each of which is filled with alluvial <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1756\">sediments<\/a> leading into playa depositional environments. During the recent <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_747\">Ice Age<\/a>, The climate was more humid and while glaciers were forming in some of the mountains, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_746\">pluvial lakes<\/a> formed covering large areas (see <a href=\"http:\/\/opengeology.org\/textbook\/14-glaciers\/#1443_Glacial_Lakes\">chapter 14.4.3<\/a>). During the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_747\">Ice Age<\/a>, valleys in much of western Utah and eastern Nevada were covered by Lake Bonneville. As the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_757\">climate<\/a> became arid after the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_747\">Ice Age<\/a>, Lake Bonneville dried leaving as a remnant the Great Salt Lake in Utah.<\/span><\/p>\n<figure id=\"attachment_3524\" aria-describedby=\"caption-attachment-3524\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/RidgecrestCA.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-836 size-medium\" title=\"Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-300x200.jpg\" alt=\"The desert has a small town\" width=\"300\" height=\"200\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-1024x683.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-768x512.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-1536x1024.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA-350x233.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RidgecrestCA.jpg 1599w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3524\" class=\"wp-caption-text\">Typical Basin and Range scene. Ridgecrest, CA sits just east of the southern Sierra Nevada Mountains.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400\">The desert of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1514\">Basin and Range<\/a> extends from about 35\u00b0 to near 40\u00b0 and results from a rain shadow effect created by westerly winds from the Pacific rising and cooling over the Sierras becoming depleted of moisture by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> on the western side. The result is relatively dry air descending across Nevada and western Utah. <\/span><\/p>\n<p><span style=\"font-weight: 400\">A journey from the Wasatch Front southwest to the Pacific Ocean will show stages of desert landscape evolution from the fault block mountains of Utah with sharp peaks and alluvial fans at the mouths of canyons, through landscapes in Southern Nevada with <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajadas<\/a> along the mountain fronts, to the\u00a0 landscapes in the Mojave Desert of California with subdued <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1505\">inselbergs<\/a> sticking up through a sea of coalesced <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajadas<\/a>. These landscapes illustrate the evolutionary stages of desert landscape development.<\/span><\/p>\n<h3><span style=\"font-weight: 400\">13.4.1 Desertification<\/span><\/h3>\n<figure id=\"attachment_3525\" aria-describedby=\"caption-attachment-3525\" style=\"width: 481px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Desertification_map.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-837\" title=\"By USDA employee\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-300x194.png\" alt=\"World map showing desertification vulnerability\" width=\"481\" height=\"311\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-300x194.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-1024x663.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-768x497.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-1536x994.png 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-65x42.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-225x146.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map-350x226.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Desertification_map.png 1700w\" sizes=\"auto, (max-width: 481px) 100vw, 481px\" \/><\/a><figcaption id=\"caption-attachment-3525\" class=\"wp-caption-text\">World map showing desertification vulnerability<\/figcaption><\/figure>\n<p><span class=\"TextRun SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">When p<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">reviously arable land<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"> suitable for agriculture<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">transforms\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">into desert, <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">this process is called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a>.\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">Plants and<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">humus-rich\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_250\">soil<\/a><\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">(<\/span><span class=\"NormalTextRun CommentStart SCXW105139879 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW105139879 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#524_Soil\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW105139879 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW105139879 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW105139879 BCX0\">) promote\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">groundwater<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">infiltration<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">and water retention.\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">When\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">an\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">area\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">becomes more arid due to changing environmental conditions<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">, the plants and\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_250\">soil<\/a><\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">become <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">less effective in retaining water<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">,<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">creating\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">a<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_759\">positive feedback<\/a><\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">loop<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a><\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">. Th<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">is<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\"> self-reinforcing loop <\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">spirals into increasingly arid conditions and further enlarges\u00a0<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">the desert<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">\u00a0regions<\/span><span class=\"NormalTextRun SCXW105139879 BCX0\">.\u00a0<\/span><\/span><span class=\"EOP SCXW105139879 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span class=\"TextRun SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW49940429 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">Desertification<\/a> may be caused\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">by<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0human\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">activities, such as\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">unsustainable<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">crop cultivation\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">practices<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">,\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">overgrazing by\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">livestock, over<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">use<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">ground<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">water<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">, and global <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_757\">climate<\/a> change<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">Human-caused d<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">esertification\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">is a serious\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">worldwide\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">problem<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">The\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">world map\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">figure above shows <\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">what\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">areas\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">are most\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">vulnerabl<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">e<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0to<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a>.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">Note the red and orange areas<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0in the\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">western and midwestern\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">regions of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">the\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">United States<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">, which also cover large areas of arable land used for raising food crops and animals.\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">T<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">he\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">creation of the <\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">Dust Bowl\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">in\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">the 1930s\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">(<\/span><span class=\"NormalTextRun CommentStart SCXW49940429 BCX0\">see\u00a0<\/span><\/span><a class=\"Hyperlink SCXW49940429 BCX0\" href=\"http:\/\/opengeology.org\/textbook\/5-weathering-erosion-and-sedimentary-rocks\/#524_Soil\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"TextRun Underlined SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"none\"><span class=\"NormalTextRun SCXW49940429 BCX0\" data-ccp-charstyle=\"Hyperlink\">Chapter 5<\/span><\/span><\/a><span class=\"TextRun SCXW49940429 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-contrast=\"auto\"><span class=\"NormalTextRun SCXW49940429 BCX0\">)\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">is a classic example of\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">a high-vulnerability region impacted by\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">human<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">&#8211;<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">caused<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a>.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0As demonstrated in the Dust Bowl, c<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">onflict<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">s may arise<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0between\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">agricultural practices<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0and conservation measures<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">.\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">M<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">itigat<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">ing<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a><\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">while allowing\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">farmers to make a survivable living requires public and individual education to create community support<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0and\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">understanding of sustainable agriculture\u00a0<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">alternatives.<\/span><span class=\"NormalTextRun SCXW49940429 BCX0\">\u00a0<\/span><\/span><span class=\"EOP SCXW49940429 BCX0\" data-ccp-props=\"{&quot;201341983&quot;:2,&quot;335559739&quot;:120,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-92\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-92\" class=\"h5p-iframe\" data-content-id=\"92\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13.4 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4730\" aria-describedby=\"caption-attachment-4730\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/13.4-Did-I-Get-It-QR-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-838\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/13.4-Did-I-Get-It-QR-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4730\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 13.4 via this QR Code.<\/figcaption><\/figure>\n<h3>Summary<\/h3>\n<p>Approximately 30% of Earth\u2019s surface is arid lands, the location of which is determined by latitude, atmospheric circulation, and terrain. The arid belts between 15<sup>o<\/sup> and 30<sup>o<\/sup> north and south latitudes are produced by descending air masses associated with major cells in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1745\">atmosphere<\/a> and include the major deserts like the Sahara in Africa and the Middle East. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1488\">Rain shadow deserts<\/a> lie behind mountain ranges or long land expanses in zones of prevailing winds like the deserts of western North America, the Atacama of South America, and the Gobi of Asia. Dry descending air also creates the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1489\">polar deserts<\/a> at the poles.<\/p>\n<p>Major atmospheric circulation involves the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley cells<\/a>, midlatitude or Ferrel cells, and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1493\">polar cells<\/a> in each hemisphere. Warmed and rising air in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1490\">Hadley cells<\/a> rains back on the tropics and moves toward the poles as dryer air. That air meets the dryer equatorward moving air of the Ferrel cells. This dry air descends in the arid zones, called the horse latitudes, to produce the arid belts in each hemisphere. Rotation of the Earth creates the Coriolis Effect that deflects these moving air masses to produce zones of prevailing winds, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1494\">Trade Winds<\/a> in the subtropics and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1495\">Westerlies<\/a> in the midlatitudes. A combination of latitude, rain shadow, and cold adjacent ocean currents causes the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1492\">Atacama Desert<\/a> of northern Chile,\u00a0 the driest desert on Earth.<\/p>\n<p><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">Weath<span style=\"font-size: 1em\">ering<\/span><\/a><span style=\"font-size: 1em\"> in deserts takes place just as in other climes only slower because of less water. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1496\">Desert varnish<\/a> is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1754\">weathering<\/a> product unique to desert environments. As in more humid climes, water is the main agent of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1755\">erosion<\/a> although wind is a notable agent. Large dust storms called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1497\">haboobs<\/a> transport large amounts of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1756\">sediment<\/a> that may accumulate in sand seas called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1508\">ergs<\/a> or finer grained loess deposits. Sand transport occurs mainly by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1498\">saltation<\/a> in which grain to grain impact causes frosting of grain surfaces. Sandblasting by persistent winds produces stones with polished surfaces called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1502\">ventifacts<\/a> and sculpted <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1023\">bedrock<\/a> features called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1501\">yardangs<\/a>.<\/span><\/p>\n<p>Landforms produced in desert environments include alluvial fans, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajadas<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1505\">inselbergs<\/a>, and playas. Windblown sand can accumulate as dunes. The forms of dunes, like barchans, parabolic, longitudinal, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1513\">star dunes<\/a>, relate to the abundance of sand supply and wind direction as well as presence of vegetation. The internal structure of dunes shows <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1509\">cross bedding<\/a>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1228\">Fossil<\/a> dunes in an ancient desert leave <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1509\">cross bedding<\/a> in places like Zion and Arches national parks in Utah showing shifting wind directions in these ancient environments. Ephemeral streams in desert regions may carry water only after storms and pose risk of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1506\">flash floods<\/a>.<\/p>\n<p>The Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">Basin<\/a> of North America is an enclosed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">basin<\/a> with no drainage to the ocean. The only exit for <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1785\">precipitation<\/a> there is by evaporation. Travels in the Great <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_508\">Basin<\/a> show stages of development of desert landscapes from playas and alluvial fans, to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1504\">bajadas<\/a>, to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1505\">inselbergs<\/a> which are eroded mountains buried in their own erosional debris.<\/p>\n<p>Poor land management can result in dying vegetation and loss of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_250\">soil<\/a> moisture producing an accelerating process of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_840_1515\">desertification<\/a> in which once productive land is degraded into unproductive desert. This is a serious worldwide problem.<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-93\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-93\" class=\"h5p-iframe\" data-content-id=\"93\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 13 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4731\" aria-describedby=\"caption-attachment-4731\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/03\/Ch.13-Review-Code.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-839\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.13-Review-Code.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4731\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 13 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<h2><\/h2>\n<ol>\n<li><span style=\"color: #000000\">Bagnold, R. A. 1941. \u201cThe Physics of Blown Sand and Desert Dunes.\u201d <em>Methum, London, UK<\/em>, 265.<\/span><\/li>\n<li><span style=\"color: #000000\">Boggs, Sam. 2006. \u201cPrinciples of Sedimentology and Stratigraphy.\u201d Pearson Prentice Hall. <a href=\"http:\/\/agris.fao.org\/agris-search\/search.do?recordID=US201300110702\" target=\"_blank\" rel=\"noopener\">http:\/\/agris.fao.org\/agris-search\/search.do?recordID=US201300110702<\/a>.<\/span><\/li>\n<li><span style=\"color: #000000\">Clements, Thomas. 1952. \u201cWind-Blown Rocks and Trails on Little Bonnie Claire Playa, Nye County, Nevada.\u201d <em>Journal of Sedimentary Research<\/em> 22 (3). Society for Sedimentary Geology. <a href=\"http:\/\/archives.datapages.com\/data\/sepm\/journals\/v01-32\/data\/022\/022003\/0182.htm\" target=\"_blank\" rel=\"noopener\">http:\/\/archives.datapages.com\/data\/sepm\/journals\/v01-32\/data\/022\/022003\/0182.htm<\/a>.<\/span><\/li>\n<li><span style=\"color: #000000\">Collado, Gonzalo A., Mois\u00e9s A. Valladares, and Marco A. M\u00e9ndez. \u201cHidden Diversity in Spring Snails from the Andean Altiplano, the Second Highest Plateau on Earth, and the Atacama Desert, the Driest Place in the World.\u201d <em>Zoological Studies <\/em>52 (1): 50.<\/span><\/li>\n<li><span style=\"color: #000000\">Easterbrook, Don J. 1999. <em>Surface Processes and Landforms<\/em>. Pearson College Division.<\/span><\/li>\n<li><span style=\"color: #000000\">Geist, Helmut. 2005. <em>The Causes and Progression of Desertification<\/em>. Ashgate Aldershot.<\/span><\/li>\n<li><span style=\"color: #000000\">Grayson, Donald K. 1993. <em>The Desert\u2019s Past: A Natural Prehistory of the Great Basin<\/em>. Smithsonian Inst Pr.<\/span><\/li>\n<li><span style=\"color: #000000\">Hadley, Geo. 1735. \u201cConcerning the Cause of the General Trade-Winds: By Geo. Hadley, Esq; FRS.\u201d <em>Philosophical Transactions<\/em> 39 (436-444). The Royal Society: 58\u201362.<\/span><\/li>\n<li><span style=\"color: #000000\">Hartley, Adrian J., and Guillermo Chong. 2002. \u201cLate Pliocene Age for the Atacama Desert: Implications for the Desertification of Western South America.\u201d <em>Geology<\/em> 30 (1). geology.gsapubs.org: 43\u201346.<\/span><\/li>\n<li><span style=\"color: #000000\">Hedin, Sven Anders. 1903. <em>Central Asia and Tibet<\/em>. Vol. 1. Hurst and Blackett, limited.<\/span><\/li>\n<li><span style=\"color: #000000\">Hooke, Roger Leb. 1967. \u201cProcesses on Arid-Region Alluvial Fans.\u201d <em>The Journal of Geology<\/em> 75 (4). journals.uchicago.edu: 438\u201360.<\/span><\/li>\n<li><span style=\"color: #000000\">King, Lester C. 1953. \u201cCANONS OF LANDSCAPE EVOLUTION.\u201d <em>Geological Society of America Bulletin<\/em> 64 (7). gsabulletin.gsapubs.org: 721\u201352.<\/span><\/li>\n<li><span style=\"color: #000000\">Kletetschka, Gunther, Roger Leb Hooke, Andrew Ryan, George Fercana, Emerald McKinney, and Kristopher P. Schwebler. 2013. \u201cSliding Stones of Racetrack Playa, Death Valley, USA: The Roles of Rock Thermal Conductivity and Fluctuating Water Levels.\u201d <em>Geomorphology <\/em>195 (August). Elsevier: 110\u201317.<\/span><\/li>\n<li><span style=\"color: #000000\">Laity, Julie E. 2009. \u201cLandforms, Landscapes, and Processes of Aeolian Erosion.\u201d In <em>Geomorphology of Desert Environments<\/em>, edited by Anthony J. Parsons and Athol D. Abrahams, 597\u2013627. Springer Netherlands.<\/span><\/li>\n<li><span style=\"color: #000000\">Littell, Eliakim, and Robert S. Littell. 1846. <em>Littell\u2019s Living Age<\/em>. T.H. Carter &amp; Company.<\/span><\/li>\n<li><span style=\"color: #000000\">Livingstone, Ian, and Andrew Warren. 1996. <em>Aeolian Geomorphology: An Introduction<\/em>. Longman.<\/span><\/li>\n<li><span style=\"color: #000000\">Muhs, Daniel R., and E. A. Bettis. 2003. \u201cQuaternary Loess-Paleosol Sequences as Examples of Climate-Driven Sedimentary Extremes.\u201d <em>Special Papers-Geological Society of America<\/em>. Boulder, Colo.; Geological Society of America; 1999, 53\u201374.<\/span><\/li>\n<li><span style=\"color: #000000\">Norris, Richard D., James M. Norris, Ralph D. Lorenz, Jib Ray, and Brian Jackson. 2014. \u201cSliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion.\u201d <em>PloS One<\/em> 9 (8). journals.plos.org: e105948.<\/span><\/li>\n<li><span style=\"color: #000000\">Shao, Yaping. 2008. <em>Physics and Modelling of Wind Erosion<\/em>. Springer Science &amp; Business Media.<\/span><\/li>\n<li><span style=\"color: #000000\">Stanley, George M. 1955. \u201cORIGIN OF PLAYA STONE TRACKS, RACETRACK PLAYA, INYO COUNTY, CALIFORNIA.\u201d <em>Geological Society of America Bulletin<\/em> 66 (11). gsabulletin.gsapubs.org: 1329\u201350.<\/span><\/li>\n<li><span style=\"color: #000000\">Walker, Alta S. 1996. \u201cDeserts: Geology and Resources.\u201d Government Printing Office. <a href=\"https:\/\/pubs.er.usgs.gov\/publication\/7000004\" target=\"_blank\" rel=\"noopener\">https:\/\/pubs.er.usgs.gov\/publication\/7000004<\/a>.<\/span><\/li>\n<li><span style=\"color: #000000\">Wilson, Ian Gordon. 1971. \u201cDesert Sandflow Basins and a Model for the Development of Ergs.\u201d <em>The Geographical Journal<\/em> 137 (2). [Wiley, Royal Geographical Society (with the Institute of British Geographers)]: 180\u201399.<\/span><\/li>\n<\/ol>\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 >Koppen_World_Map_BWh       <\/li><li >Rainshadow       <\/li><li >OwensLake       <\/li><li >Rain Shadow Youtube QR Code       <\/li><li >Earth_Global_Circulation       <\/li><li >Central_Basin_and_Range_ecoregion       <\/li><li >Atacama_map.svg       <\/li><li >polar_vortex       <\/li><li >13.2_Corioliskraftanimation       <\/li><li >Coriolis Effect E-W       <\/li><li >Coriolis_effect14       <\/li><li >Corrientes-oceanicas       <\/li><li >The Coriolis Effect Explained Youtube QR Code       <\/li><li >13.1 Did I Get It QR Code       <\/li><li >Newspaper_Rock_Full       <\/li><li >MN7       <\/li><li >Saltation-mechanics       <\/li><li >Windblown_sand_grains_CoralPinkSandDunesSand       <\/li><li >2006_1205_135618-DVNP-RACETRACK       <\/li><li >Yardang_Im_Salar_de_Uyuni       <\/li><li >Blowout_Earth_TX       <\/li><li >13.2 Did I Get It QR Code       <\/li><li >Alluvial_Fan       <\/li><li >Inselbergs_in_Mojave_Desert       <\/li><li >Dry_Wash_in_PEFO_NP       <\/li><li >Flash_flood_in_the_desert       <\/li><li >Formation-of-cross_beds       <\/li><li >Barchan_dune_field_coastal_Brazil       <\/li><li >Linear_Dunes,_Great_Sand_Sea,_Egypt_-_NASA_Earth_Observatory       <\/li><li >usgs_parabolic_dunes_Cape_Cod       <\/li><li >Sahara_Star-dune       <\/li><li >13.3 Did I Get It QR Code       <\/li><li >Greatbasinmap       <\/li><li >RidgecrestCA       <\/li><li >Desertification_map       <\/li><li >13.4 Did I Get It QR Code       <\/li><li >Ch.13 Review Code       <\/li><\/ul><\/div><div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">d\u00e9finition<\/span><template id=\"term_840_2450\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2450\"><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_840_1754\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1754\"><div tabindex=\"-1\"><p>Large metallic mineral deposit that forms near magma bodies like plutons. Commonly contains copper, lead, zinc, molybdenum, 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_840_1755\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1757\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1757\"><div tabindex=\"-1\"><p>Low grade, broad deposits of microscopic gold found in sedimentary rocks with diagenetic alteration.<\/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_840_1947\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1947\"><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_840_1514\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1980\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1980\"><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_840_1785\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1767\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1745\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1494\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1494\"><div tabindex=\"-1\"><p>Second-fastest seismic wave that has a sheer motion.<\/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_840_1492\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1492\"><div tabindex=\"-1\"><p>Seismic waves that travel through the Earth, mainly P waves and S waves.<\/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_840_1489\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1489\"><div tabindex=\"-1\"><p>The location at the surface directly above the focus of an earthquake, typically associated with strong damage.<\/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_840_1653\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_2451\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2451\"><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_840_1490\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1490\"><div tabindex=\"-1\"><p>The fastest seismic wave that occurs after an earthquake, compressional in nature.<\/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_840_1493\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1493\"><div tabindex=\"-1\"><p>Seismic waves that only move along the surface, mainly R waves and L waves.<\/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_840_1495\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1495\"><div tabindex=\"-1\"><p>Waves that change direction due to changing speeds, typically caused by a change in density of the medium.<\/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_840_1491\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1491\"><div tabindex=\"-1\"><p>Energy that radiates from fault movement via earthquakes.<\/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_840_1968\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1968\"><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_840_508\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_503\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_503\"><div tabindex=\"-1\"><p>By Inglesenargentina (talk) (Uploads) (Own work) [Public domain], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3ABell-shaped-curve.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_840_1659\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1478\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1478\"><div tabindex=\"-1\"><p>A low-angle reverse fault, common in mountain building.<\/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_840_756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_756\"><div tabindex=\"-1\"><p>By McKay Savage from London, UK [<a href=\"http:\/\/creativecommons.org\/licenses\/by\/2.0\">CC BY 2.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AChina_-_Yangshuo_14_-_karst_peaks_tower_over_the_paddy_fields_(140904310).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_840_2212\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2212\"><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_840_1890\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1890\"><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_840_2205\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2205\"><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_840_254\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_254\"><div tabindex=\"-1\"><p>By Mike Beauregard from Nunavut, Canada (Franklin dike) [<a href=\"https:\/\/creativecommons.org\/licenses\/by\/2.0\">CC BY 2.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:Franklin_dike_on_northwestern_Baffin_Island..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_840_1506\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1506\"><div tabindex=\"-1\"><p>Increased intensity due to being along the path of fault propagation.<\/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_840_1496\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1496\"><div tabindex=\"-1\"><p>Surface waves that have a side-to-side motion.<\/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_840_1765\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_971\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1497\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1497\"><div tabindex=\"-1\"><p>Surface waves that have a up and down motion.<\/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_840_1987\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1987\"><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_840_1519\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_747\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_2222\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2222\"><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_840_2223\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2223\"><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_840_1498\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1498\"><div tabindex=\"-1\"><p>Waves that bounce off of a boundary between mediums of different 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_840_1023\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1907\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1907\"><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_840_1499\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1499\"><div tabindex=\"-1\"><p>Instrument used to measure seismic energy.<\/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_840_4823\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_4823\"><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_840_1500\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1500\"><div tabindex=\"-1\"><p>A process of using 3D seismic arrays to get subsurface images.<\/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_840_1984\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1984\"><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_840_1501\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1501\"><div tabindex=\"-1\"><p>Areas that have an unpredicted change in seismic data, indicating a change in 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_840_1502\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1502\"><div tabindex=\"-1\"><p>A measure of earthquake strength. Scales include Richter and Moment.<\/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_840_1503\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1503\"><div tabindex=\"-1\"><p>A magnitude scale using the amplitude of shaking via a seismograph.<\/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_840_1982\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1982\"><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_840_1742\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1979\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1979\"><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_840_1652\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1652\"><div tabindex=\"-1\"><p>Rocks that move along thin ice sheets with high winds.<\/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_840_1504\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1504\"><div tabindex=\"-1\"><p>A magnitude scale based on calculation of the energy released in an earthquake.<\/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_840_1505\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1505\"><div tabindex=\"-1\"><p>A qualitative earthquake scale, from I-XII, of the degree of shaking in an earthquake.<\/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_840_1936\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1936\"><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_840_2211\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2211\"><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_840_1244\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_250\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_250\"><div tabindex=\"-1\"><p>By Amcyrus2012 (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by\/4.0\">CC BY 4.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3ADiorite_MA.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_840_1507\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1507\"><div tabindex=\"-1\"><p>An amplification of earthquake waves due to a structure of buildings or structures.<\/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_840_2210\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2210\"><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_840_2208\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2208\"><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_840_1508\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1508\"><div tabindex=\"-1\"><p>Average time between earthquakes calculated based on past earthquake records.<\/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_840_1986\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1986\"><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_840_1509\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1509\"><div tabindex=\"-1\"><p>Length of fault without earthquake activity, due to a locked segment of a fault.<\/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_840_2193\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2193\"><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_840_479\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1243\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1912\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1912\"><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_840_2038\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2038\"><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_840_486\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_967\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1753\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1270\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1511\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1511\"><div tabindex=\"-1\"><p>Place where fault movement cuts the surface of the Earth.<\/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_840_1512\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1512\"><div tabindex=\"-1\"><p>A process of injecting pressurized fluids into the ground to aid in hydrocarbon migration.<\/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_840_1513\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1513\"><div tabindex=\"-1\"><p>Earthquakes that occur due to human activity.<\/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_840_1703\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1703\"><div tabindex=\"-1\"><p>Lakes that form via increased precipitation with glacial climate shifts.<\/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_840_1704\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1704\"><div tabindex=\"-1\"><p>A period of cooler temperatures on Earth in which ice sheets can grow on continents.<\/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_840_2148\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2148\"><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_840_492\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1668\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_1960\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1960\"><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_840_746\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_746\"><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_840_757\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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_840_2143\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2143\"><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_840_1515\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1515\"><div tabindex=\"-1\"><p>Loose material that is a mixture of soil components and weathered bedrock sediments.<\/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_840_1897\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1897\"><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_840_2207\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2207\"><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_840_2206\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_2206\"><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_840_759\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_759\"><div tabindex=\"-1\"><p>By Brocken Inaglory (Own work) [<a href=\"http:\/\/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%3ADead_trees_at_Mammoth_Hot_Springs.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_840_1488\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_1488\"><div tabindex=\"-1\"><p>Earthquake(s) that occur after the mainshock, usually decreasing in amount and magnitude over time.<\/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_840_1228\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_840_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><\/div>","protected":false},"author":291,"menu_order":13,"template":"","meta":{"pb_show_title":"","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[49],"contributor":[],"license":[],"class_list":["post-840","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":19,"_links":{"self":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/840","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\/840\/revisions"}],"predecessor-version":[{"id":1802,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/840\/revisions\/1802"}],"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\/840\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/media?parent=840"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapter-type?post=840"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/contributor?post=840"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/license?post=840"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}