{"id":795,"date":"2021-12-17T21:53:23","date_gmt":"2021-12-17T21:53:23","guid":{"rendered":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/12-shorelines\/"},"modified":"2022-05-18T14:11:28","modified_gmt":"2022-05-18T14:11:28","slug":"12-shorelines","status":"publish","type":"chapter","link":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/12-shorelines\/","title":{"raw":"12 Coastlines","rendered":"12 Coastlines"},"content":{"raw":"[caption id=\"attachment_3461\" align=\"aligncenter\" width=\"873\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/PP3.jpg\"><img class=\"wp-image-766\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-300x225.jpg\" alt=\"The beach is over sunset.\" width=\"873\" height=\"655\"><\/a> Sunset over the coastline of Puerto Pe\u00f1asco, M\u00e9xico. Because of the narrow Gulf of California, Puerto Pe\u00f1asco has one of the largest tidal ranges in western North America.[\/caption]\n<h1>12 Coastlines<\/h1>\n<b>KEY CONCEPTS<\/b>\n\nBy the end of this chapter, students should be able to:\n<ul>\n \t<li>Describe how waves occur, move, and carry energy<\/li>\n \t<li>Explain wave behavior approaching the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary]<\/li>\n \t<li>Describe [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] features and zones<\/li>\n \t<li>Describe [pb_glossary id=\"2169\"]wave refraction[\/pb_glossary] and its contribution to [pb_glossary id=\"2283\"]longshore currents[\/pb_glossary] and [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary]<\/li>\n \t<li>Explain how [pb_glossary id=\"2283\"]longshore currents[\/pb_glossary] cause the [pb_glossary id=\"2038\"]formation[\/pb_glossary] of spits and baymouth bars<\/li>\n \t<li>Distinguish between [pb_glossary id=\"2290\"]submergent[\/pb_glossary] and [pb_glossary id=\"2289\"]emergent[\/pb_glossary] coasts and describe coastal features associated with each<\/li>\n \t<li>Describe the relationship between the natural [pb_glossary id=\"2212\"]river[\/pb_glossary] of sand in the [pb_glossary id=\"1974\"]littoral[\/pb_glossary] zone and human attempts to alter it for human convenience<\/li>\n \t<li>Describe the pattern of the main ocean currents and explain the different factors involved in surface currents and deep ocean currents<\/li>\n \t<li>Explain how ocean tides occur and distinguish among diurnal, semidiurnal, and [pb_glossary id=\"1486\"]mixed tide[\/pb_glossary] patterns<\/li>\n<\/ul>\n<ul>\n \t<li style=\"list-style-type: none\">\n<ul>\n \t<li style=\"list-style-type: none\"><\/li>\n<\/ul>\n<\/li>\n<\/ul>\nThe Earth\u2019s surface is 29% land and 71% water. Coastlines are the interfaces between, and as such, the longest visible boundaries on Earth. To understand the processes that occur at these boundaries, it is important to first understand wave energy.\n<h2><span style=\"font-weight: 400\">12.1 Waves and Wave Processes<\/span><\/h2>\n[caption id=\"attachment_3462\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Deep_water_wave.gif\"><img class=\"wp-image-767 size-medium\" title=\"By Kraaiennest (Own work) \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-300x197.gif\" alt=\"The particles move in roughly circular motion.\" width=\"300\" height=\"197\"><\/a> Particle motion within a wind-blown wave.[\/caption]\n\nWind blowing over the surface of water transfers energy to the water through friction. The energy transferred from wind to water causes waves to form. Waves move as individual oscillating particles of water. As the [pb_glossary id=\"2260\"]wave crest[\/pb_glossary] passes, the water is moving forward. As the [pb_glossary id=\"2261\"]wave trough[\/pb_glossary] passes, the water is moving backward. To see wave movement in action, watch a cork or some floating object as a wave passes.\n\n<span style=\"font-weight: 400\">\u00a0<\/span>\n\n[caption id=\"attachment_3463\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Water_wave_diagram.jpg\"><img class=\"wp-image-768 size-medium\" title=\"By NOAA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-300x152.jpg\" alt=\"Crest, trough, period, wavelength are labeled.\" width=\"300\" height=\"152\"><\/a> Aspects of water waves, labeled.[\/caption]Important terms to understand in the operation of waves include: the <strong>[pb_glossary id=\"2260\"]wave crest[\/pb_glossary]<\/strong> is the highest point of the wave; the <strong>[pb_glossary id=\"2261\"]trough[\/pb_glossary]<\/strong> is the lowest point of the wave. <strong>[pb_glossary id=\"2263\"]Wave height[\/pb_glossary] <\/strong>is the vertical distance from the [pb_glossary id=\"2261\"]trough[\/pb_glossary] to the crest and is determined by wave energy. W<strong>ave [pb_glossary id=\"2262\"]amplitude[\/pb_glossary] <\/strong>is half the [pb_glossary id=\"2263\"]wave height[\/pb_glossary], or the distance from either the crest or trough to the still water line. <strong>[pb_glossary id=\"2264\"]Wavelength[\/pb_glossary]<\/strong> is the horizontal distance between consecutive wave crests. <strong>[pb_glossary id=\"2265\"]Wave velocity[\/pb_glossary]<\/strong> is the speed at which a [pb_glossary id=\"2260\"]wave crest[\/pb_glossary] moves forward and is related to the wave\u2019s energy. <strong>[pb_glossary id=\"2266\"]Wave period[\/pb_glossary]<\/strong> is the time interval it takes for adjacent wave crests to pass a given point.\n\n[caption id=\"attachment_3097\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Wavebase.jpg\"><img class=\"wp-image-408 size-medium\" title=\"https:\/\/en.wikipedia.org\/wiki\/File:Wavebase.jpg, by https:\/\/en.wikipedia.org\/wiki\/User:GregBenson: Permission is granted to copy, distribute and\/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-300x218.jpg\" alt=\"The diagram shows that wavebase is 1\/2 the wavelength of waves of water.\" width=\"300\" height=\"218\"><\/a> Diagram describing wavebase.[\/caption]\n\nThe circular motion of water particles diminishes with depth and is negligible at about one-half [pb_glossary id=\"2264\"]wavelength[\/pb_glossary], an important dimension to remember in connection with waves. <strong>[pb_glossary id=\"2267\"]Wave base[\/pb_glossary]<\/strong> is the vertical depth at which water ceases to be disturbed by waves. In water shallower than [pb_glossary id=\"2267\"]wave base[\/pb_glossary], waves will disturb the bottom and [pb_glossary id=\"1946\"]ripple[\/pb_glossary] [pb_glossary id=\"2273\"]shore[\/pb_glossary] sand. [pb_glossary id=\"2267\"]Wave base[\/pb_glossary] is measured at a depth of about one-half [pb_glossary id=\"2264\"]wavelength[\/pb_glossary], where the water particles\u2019 circular motion diminishes to zero. If waves approaching a beach have crests at about 6 m (~20 ft) intervals, this wave motion disturbs water to about 3 m (~10 ft) deep. This motion is known as f<strong>air-[pb_glossary id=\"756\"]weather[\/pb_glossary] [pb_glossary id=\"2267\"]wave base[\/pb_glossary]<\/strong>. In strong storms such as hurricanes, both [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] and [pb_glossary id=\"2267\"]wave base[\/pb_glossary] increase dramatically to a depth known as <strong>[pb_glossary id=\"2269\"]storm wave base[\/pb_glossary]<\/strong>, which is approximately 91 m (~300 ft) <span class=\"FindHit BCX0 SCXW110913762\">[<\/span><span class=\"NormalTextRun BCX0 SCXW110913762\">1]<\/span>.\n\nWaves are generated by wind blowing across the ocean surface. The amount of energy imparted to the water depends on wind velocity and the distance across which the wind is blowing. This distance is called <strong>[pb_glossary id=\"2270\"]fetch[\/pb_glossary]<\/strong>. Waves striking a [pb_glossary id=\"2273\"]shore[\/pb_glossary] are typically generated by storms hundreds of miles from the [pb_glossary id=\"1968\"]coast[\/pb_glossary] and have been traveling across the ocean for days.\n\n[caption id=\"attachment_3464\" align=\"alignright\" width=\"200\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Wave_packet_dispersion.gif\"><img class=\"wp-image-769 size-full\" title=\"By Fffred~commonswiki\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wave_packet_dispersion.gif\" alt=\"The wave moves across the image.\" width=\"200\" height=\"115\"><\/a> Wave train moving with dispersion.[\/caption]\n\n&nbsp;\n\nWinds blowing in a relatively constant direction generate waves moving in that direction. Such a group of approximately parallel waves traveling together is called a <strong>[pb_glossary id=\"2271\"]wave train[\/pb_glossary]<\/strong>.\u00a0 A [pb_glossary id=\"2271\"]wave train[\/pb_glossary] coming from one [pb_glossary id=\"2270\"]fetch[\/pb_glossary] can produce various wavelengths. Longer wavelengths travel at a faster velocity than shorter wavelengths, so they arrive first at a distant [pb_glossary id=\"2273\"]shore[\/pb_glossary]. Thus, there is a [pb_glossary id=\"2264\"]wavelength[\/pb_glossary]-[pb_glossary id=\"1907\"]sorting[\/pb_glossary] process that takes place during the [pb_glossary id=\"2271\"]wave train[\/pb_glossary]\u2019s travel. This [pb_glossary id=\"1907\"]sorting[\/pb_glossary] process is called <strong>wave dispersion<\/strong>.\n\n<b style=\"font-size: 23px\">1<\/b><b style=\"font-size: 23px\">2.1.1 Behavior of Waves Approaching [pb_glossary id=\"2273\"]Shore[\/pb_glossary]<\/b>\n\n[caption id=\"attachment_3465\" align=\"alignleft\" width=\"238\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Breaking_wave_types.svg_.png\"><img class=\"wp-image-770 size-medium\" title=\"By Kraaiennest\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-238x300.png\" alt=\"There are four types of breakers\" width=\"238\" height=\"300\"><\/a> Types of breakers[\/caption]\n\nOn the open sea, waves generally appear choppy because wave trains from many directions are interacting with each other, a process called wave interference. Constructive interference occurs where crests align with other crests. The aligned wave height is the sum of the individual [pb_glossary id=\"2263\"]wave heights[\/pb_glossary], a process referred to as <em>wave amplification.<\/em> Constructive interference also produces hollows where troughs align with other troughs. Destructive interference occurs where crests align with troughs and cancel each other out. As waves approach [pb_glossary id=\"2273\"]shore[\/pb_glossary] and begin to make frictional contact with the sea floor at a depth of about one-half [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] or less, they begin to slow down. However, the energy carried by the wave remains the same, so the waves build up higher. Remember that water moves in a circular motion as a wave passes, and each circle is fed from the [pb_glossary id=\"2261\"]trough[\/pb_glossary] in front of the advancing wave. As the wave encounters shallower water at the [pb_glossary id=\"2273\"]shore[\/pb_glossary], there is eventually insufficient water in the [pb_glossary id=\"2261\"]trough[\/pb_glossary] in front of the wave to supply a complete circle, so the crest pours over creating a <strong>breaker<\/strong>.\n\n[caption id=\"attachment_3466\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Propagation_du_tsunami_en_profondeur_variable.gif\"><img class=\"wp-image-771 size-medium\" title=\"By R\u00e9gis Lachaume (Own work)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-300x157.gif\" alt=\"The waves get taller in shallow water.\" width=\"300\" height=\"157\"><\/a> All waves, like tsunamis, slow down as they reach shallow water. This causes the wave to increase in hight.[\/caption]\n\nA special type of wave is called a <strong>[pb_glossary id=\"2272\"]tsunami[\/pb_glossary],<\/strong> sometimes incorrectly called a \"tidal wave.\" [pb_glossary id=\"2272\"]Tsunamis[\/pb_glossary] are generated by energetic events affecting the sea floor, such as earthquakes, submarine [pb_glossary id=\"246\"]landslides[\/pb_glossary], and [pb_glossary id=\"228\"]volcanic[\/pb_glossary] eruptions (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/9-crustal-deformation-and-earthquakes\/\">Chapter 9<\/a> and <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>). During earthquakes for example, [pb_glossary id=\"2272\"]tsunamis[\/pb_glossary] can be produced when the moving crustal rocks below the sea abruptly elevate a portion of the seafloor. Water is suddenly lifted creating a bulge at the surface and a [pb_glossary id=\"2271\"]wave train[\/pb_glossary] spreads out in all directions traveling at tremendous speeds [over 322 kph (200 mph)] and carrying enormous energy. [pb_glossary id=\"2272\"]Tsunamis[\/pb_glossary] may pass unnoticed in the open ocean because they move so fast, the [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] is very long, and the [pb_glossary id=\"2263\"]wave height[\/pb_glossary] is very low. But, as the [pb_glossary id=\"2271\"]wave train[\/pb_glossary] approaches [pb_glossary id=\"2273\"]shore[\/pb_glossary] and each wave begins to interact with the shallow seafloor, friction increases and the wave slows down. Still carrying its enormous energy, wave height builds up and the wave strikes the shore as a wall of water that can be over 30 m (~100 ft)\u00a0 high. The [pb_glossary id=\"985\"]massive[\/pb_glossary] wave, called a [pb_glossary id=\"2272\"]tsunami[\/pb_glossary] runup, may sweep inland well beyond the beach destroying structures far inland. [pb_glossary id=\"2272\"]Tsunamis[\/pb_glossary] can deliver a catastrophic blow to people at the beach. As the [pb_glossary id=\"2261\"]trough[\/pb_glossary] water in front of the [pb_glossary id=\"2272\"]tsunami[\/pb_glossary] wave is drawn back, the seafloor is exposed. Curious and unsuspecting people on the beach may run out to see exposed [pb_glossary id=\"2274\"]offshore[\/pb_glossary] sea life only to be overwhelmed when the breaking crest hits.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"85\"]\n\n[caption id=\"attachment_4709\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.1-Did-I-Get-It-QR-Code-1.png\"><img class=\"size-thumbnail wp-image-772\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 12.1 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">12.2 Shoreline Features<\/span><\/h2>\n<strong>Coastlines<\/strong> are dynamic, high energy, and geologically complicated places where many different erosional and depositional features exist (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>). They include all parts of the land-sea boundary directly affected by the sea, including land far above high [pb_glossary id=\"1480\"]tide[\/pb_glossary] and seafloor well below normal [pb_glossary id=\"2267\"]wave base[\/pb_glossary]. But, the<strong> [pb_glossary id=\"2273\"]shoreline[\/pb_glossary]<\/strong> itself is the direct interface between water and land that shifts with the tides. This shifting interface at the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] is called the<strong> [pb_glossary id=\"1974\"]littoral[\/pb_glossary]<\/strong> zone. The combination of waves, currents, [pb_glossary id=\"757\"]climate[\/pb_glossary], coastal morphology, and gravity, all act on this land-sea boundary to create [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] features.\n<h3><strong>12.2.1 Shoreline Zones<\/strong><\/h3>\n[caption id=\"attachment_3467\" align=\"alignleft\" width=\"441\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Littoral_Zones-1.jpg\"><img class=\"wp-image-409\" title=\"US Navy, [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1.jpg\" alt=\"The image shows the many complexities of the shoreline described in the text.\" width=\"441\" height=\"193\"><\/a> Diagram of zones of the shoreline.[\/caption]&nbsp;\n\nShorelines are divided into five primary zones\u2014[pb_glossary id=\"2274\"]offshore[\/pb_glossary], [pb_glossary id=\"2275\"]nearshore[\/pb_glossary], surf, [pb_glossary id=\"2277\"]foreshore[\/pb_glossary], and [pb_glossary id=\"2282\"]backshore[\/pb_glossary]. The <strong>[pb_glossary id=\"2274\"]offshore[\/pb_glossary]<\/strong> zone is below water, but it is still geologically active due to flows of [pb_glossary id=\"2303\"]turbidity currents[\/pb_glossary] that cascade over the [pb_glossary id=\"1970\"]continental slope[\/pb_glossary] and accumulate in the [pb_glossary id=\"1653\"]continental[\/pb_glossary] rise. The <strong>[pb_glossary id=\"2275\"]nearshore[\/pb_glossary]<\/strong> zone is the area of the [pb_glossary id=\"2273\"]shore[\/pb_glossary] affected by the waves where water depth is one-half wavelength or less. The width of this zone depends on the maximum [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] of the approaching [pb_glossary id=\"2271\"]wave train[\/pb_glossary] and the slope of the seafloor. The [pb_glossary id=\"2275\"]nearshore[\/pb_glossary] zone includes the <strong>[pb_glossary id=\"1967\"]shoreface[\/pb_glossary]<\/strong>, which is where sand is disturbed and deposited. The [pb_glossary id=\"1967\"]shoreface[\/pb_glossary] is broken into two segments: upper and lower [pb_glossary id=\"1967\"]shoreface[\/pb_glossary]. Upper [pb_glossary id=\"1967\"]shoreface[\/pb_glossary] is affected by everyday wave action and consists of finely-laminated and cross-bedded sand. The lower [pb_glossary id=\"1967\"]shoreface[\/pb_glossary] is the only area moved by storm waves and consists of hummocky cross-stratified sand. The <strong>surf zon<\/strong>e is where the waves break.\n\nThe <strong>[pb_glossary id=\"2277\"]foreshore[\/pb_glossary]<\/strong> zone overlaps the [pb_glossary id=\"2276\"]surf zone[\/pb_glossary] and is periodically wet and dry due to waves and tides. The [pb_glossary id=\"2277\"]foreshore[\/pb_glossary] zone is where planer-laminated, well-sorted sand accumulates. The [pb_glossary id=\"2278\"]beach face[\/pb_glossary] is the part of the [pb_glossary id=\"2277\"]foreshore[\/pb_glossary] zone where the breaking waves swash up and the backwash flows back down. Low ridges above the [pb_glossary id=\"2278\"]beach face[\/pb_glossary] in the [pb_glossary id=\"2277\"]foreshore[\/pb_glossary] zone are called [pb_glossary id=\"2279\"]berms[\/pb_glossary]. During the summer in North America, when most people visit the beach, the zone where people spread their towels and beach umbrellas is the <strong>[pb_glossary id=\"2280\"]summer berm[\/pb_glossary]<\/strong>. Wave energy is typically lower in the summer, which allows sand to pile onto the beach. Behind the [pb_glossary id=\"2280\"]summer berm[\/pb_glossary] is a low ridge of sand called the <strong>[pb_glossary id=\"2281\"]winter berm[\/pb_glossary]<\/strong><em>.<\/em> In winter, higher storm energy moves the [pb_glossary id=\"2280\"]summer berm[\/pb_glossary] sand off the beach and piles it in the [pb_glossary id=\"2275\"]nearshore[\/pb_glossary] zone. The next year, that sand is replaced on the beach and moved back onto the [pb_glossary id=\"2280\"]summer berm[\/pb_glossary]. The <strong>[pb_glossary id=\"2282\"]backshore[\/pb_glossary]<\/strong> zone is the area always above sea level in normal conditions. In the [pb_glossary id=\"2282\"]backshore[\/pb_glossary] zone<em>,<\/em> onshore winds may blow sand behind the beach and the [pb_glossary id=\"2279\"]berms[\/pb_glossary], creating [pb_glossary id=\"1947\"]dunes[\/pb_glossary].\n<h3><b>12.2.2 Refraction, Longshore Currents, and Longshore Drift<\/b><\/h3>\n[caption id=\"attachment_3468\" align=\"alignright\" width=\"195\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Longshore.png\"><img class=\"wp-image-773 size-medium\" title=\"By USGS\/USGov, modified by Eurico Zimbres [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-195x300.png\" alt=\"The waves move sand along the beach.\" width=\"195\" height=\"300\"><\/a> Longshore Drift. 1=beach, 2=sea, 3=longshore current direction, 4=incoming waves, 5=swash, 6=backwash[\/caption]&nbsp;\n\nAs waves enter shallower water less than one-half [pb_glossary id=\"2264\"]wavelength[\/pb_glossary] depth, they slow down. Waves usually approach the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] at an angle, with the end of the waves nearest the beach slowing down first. This causes the wave crests to bend,\u00a0 called <strong>[pb_glossary id=\"2169\"]wave refraction[\/pb_glossary]<\/strong>. From the [pb_glossary id=\"2278\"]beach face[\/pb_glossary], this causes it to look like waves are approaching the beach straight on, parallel to the beach. However, as refracted waves actually approach the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] at a slight angle, they create a slight difference between the swash as it moves up the [pb_glossary id=\"2278\"]beach face[\/pb_glossary] at a slight angle and the backwash as it flows straight back down under gravity. This slight angle between swash and backwash along the beach creates a current called the l<strong>ongshore current<\/strong>. Waves stir up sand in the [pb_glossary id=\"2276\"]surf zone[\/pb_glossary] and move it along the [pb_glossary id=\"2273\"]shore[\/pb_glossary]. This movement of sand is called <strong>[pb_glossary id=\"2284\"]longshore drift[\/pb_glossary]<\/strong>. [pb_glossary id=\"2284\"]Longshore drift[\/pb_glossary] along both the west and east coasts of North America moves sand north to south on average.\n\n[caption id=\"attachment_3469\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/FarewellSpitNZ.jpg\"><img class=\"wp-image-774 size-medium\" title=\"By NASA\/GSFC\/METI\/ERSDAC\/JAROS, and U.S.\/Japan ASTER Science Team (NASA's Earth Observatory) [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-300x193.jpg\" alt=\"The spit is a long ridge of sand\" width=\"300\" height=\"193\"><\/a> Farewell Spit, New Zealand[\/caption][pb_glossary id=\"2283\"]Longshore currents [\/pb_glossary]can carry [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary] down a [pb_glossary id=\"1968\"]coast[\/pb_glossary] until it reaches a bay or inlet where it will deposit sand in the quieter water (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/11-water\/\">Chapter 11<\/a>). Here, a <strong>[pb_glossary id=\"2285\"]spit[\/pb_glossary]<\/strong> can form. As the [pb_glossary id=\"2285\"]spit[\/pb_glossary] grows, it may extend across the [pb_glossary id=\"1776\"]mouth[\/pb_glossary] of the bay forming a barrier called a <strong>[pb_glossary id=\"2286\"]baymouth bar[\/pb_glossary]<\/strong>. Where the bay or inlet serves as boat anchorage, spits and baymouth bars are a severe inconvenience. Often, inconvenienced communities create methods to keep their bays and harbors open<span style=\"font-weight: 400\">.<\/span>\n\n[caption id=\"attachment_3470\" align=\"alignright\" width=\"295\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Jetty.jpg\"><img class=\"wp-image-775 size-full\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Jetty.jpg\" alt=\"The two jetties led to a coastal waterway.\" width=\"295\" height=\"197\"><\/a> Jetties near Carlsbad, California. Notice the left jetty is loaded with sand, while the right jetty is lacking sand. This is due to the longshore drift going left to right.[\/caption]\n\nOne way to keep a harbor open is to build a <strong>[pb_glossary id=\"2287\"]jetty[\/pb_glossary],<\/strong> a long concrete or stone barrier constructed to deflect the sand away from a harbor [pb_glossary id=\"1776\"]mouth[\/pb_glossary] or other ocean waterway. If the [pb_glossary id=\"2287\"]jetty[\/pb_glossary] does not deflect the sand far enough out, sand may continue to flow along the [pb_glossary id=\"2273\"]shore[\/pb_glossary], forming a [pb_glossary id=\"2285\"]spit[\/pb_glossary] around the end of the [pb_glossary id=\"2287\"]jetty[\/pb_glossary]. A more expensive but effective method to keep a bay [pb_glossary id=\"1776\"]mouth[\/pb_glossary] open is to dredge the sand from the growing spit, put it on barges, and deliver it back to the drift downstream of the harbor [pb_glossary id=\"1776\"]mouth[\/pb_glossary]. An even more expensive but more effective option is to install large pumps and pipes to draw in the sand upstream of the harbor, pump it through pipes, and [pb_glossary id=\"2214\"]discharge[\/pb_glossary] it back into the drift downstream of the harbor [pb_glossary id=\"1776\"]mouth[\/pb_glossary]. Because natural processes work continuously, human efforts to mitigate inconvenient spits and baymouth bars require ongoing modifications. For example, the community of Santa Barbara, California, tried several methods to keep their harbor open before settling on pumps and piping<span class=\"NormalTextRun BCX0 SCXW116966205\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW116966205\">[<\/span><span class=\"NormalTextRun BCX0 SCXW116966205\">2<\/span><span class=\"NormalTextRun BCX0 SCXW116966205\">]<\/span>.\n\n[caption id=\"attachment_3471\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/RipCurrent.gif\"><img class=\"wp-image-776 size-medium\" title=\"By National Weather Service, Wilmington, NC (NOAA) [Public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-300x300.gif\" alt=\"Some water is rushing outwards while most water rushes in toward the shore.\" width=\"300\" height=\"300\"><\/a> Animation of rip currents.[\/caption][pb_glossary id=\"2288\"]Rip currents[\/pb_glossary] are another coastal phenomenon related to [pb_glossary id=\"2283\"]longshore currents[\/pb_glossary]. <strong>[pb_glossary id=\"2288\"]Rip currents[\/pb_glossary]<\/strong> occur in the [pb_glossary id=\"2275\"]nearshore[\/pb_glossary] seafloor when wave trains come <em>straight <\/em>onto the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary]<strong>.<\/strong> In areas where wave trains push water directly toward the [pb_glossary id=\"2278\"]beach face[\/pb_glossary] or where the shape of the [pb_glossary id=\"2275\"]nearshore[\/pb_glossary] seafloor refracts waves toward a specific point on the beach, the water piles up on [pb_glossary id=\"2273\"]shore[\/pb_glossary]. But this water must find an outlet back to the sea. The outlet is relatively narrow, and [pb_glossary id=\"2288\"]rip currents[\/pb_glossary] carry the water directly away from the beach. Swimmers caught in [pb_glossary id=\"2288\"]rip currents[\/pb_glossary] are carried out to sea. Swimming back to [pb_glossary id=\"2273\"]shore[\/pb_glossary] directly against the strong current is fruitless. A [pb_glossary id=\"1783\"]solution[\/pb_glossary] for good swimmers is to ride out the current to where it dissipates, swim around it, and return to the beach. Another [pb_glossary id=\"1783\"]solution[\/pb_glossary] for average swimmers is to swim parallel to the beach until out of the current, then return to the beach. Where [pb_glossary id=\"2288\"]rip currents[\/pb_glossary] are known to exist, warning signs are often posted. The best [pb_glossary id=\"1783\"]solution[\/pb_glossary] is to understand the nature of [pb_glossary id=\"2288\"]rip currents[\/pb_glossary], have a plan before entering the water, or watch the signs and avoid them all together.\n\nLike [pb_glossary id=\"2288\"]rip currents[\/pb_glossary], undertow is a current that moves away from the shore. However, unlike [pb_glossary id=\"2288\"]rip currents[\/pb_glossary], undertow occurs underneath the approaching waves and is strongest in the [pb_glossary id=\"2276\"]surf zone[\/pb_glossary] where waves are high and water is shallow. Undertow is another return flow for water transported onshore by waves.\n<h3><b>12.2.3 Emergent and Submergent Coasts<\/b><\/h3>\n[caption id=\"attachment_3472\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08.jpg\"><img class=\"wp-image-777 size-medium\" title=\"Diliff \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-300x106.jpg\" alt=\"The arch is a rock in the water with a hole in the middle which allows water to pass through.\" width=\"300\" height=\"106\"><\/a> Island Arch, a sea arch in Victoria, Australia.[\/caption]\n\n<strong>[pb_glossary id=\"2289\"]Emergent[\/pb_glossary]<\/strong> coasts occur where sea levels fall relative to land level. <strong>[pb_glossary id=\"2290\"]Submergent[\/pb_glossary]<\/strong> coasts occur where sea levels rise relative to land level. [pb_glossary id=\"1654\"]Tectonic[\/pb_glossary] shifts and sea level changes cause the long-term rise and fall of sea level relative to land. Some features associated with [pb_glossary id=\"2289\"]emergent[\/pb_glossary] coasts include high cliffs, headlands, exposed [pb_glossary id=\"1023\"]bedrock[\/pb_glossary], steep slopes, rocky shores, arches, stacks, tombolos, wave-cut [pb_glossary id=\"1260\"]platforms[\/pb_glossary], and wave notches.\n\n[caption id=\"attachment_3473\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Angel_Road_Shodo_Island_Japan01s3.jpg\"><img class=\"wp-image-778 size-medium\" title=\"By 663highland\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-300x200.jpg\" alt=\"The rock in the ocean is connected by the sandy tombolo.\" width=\"300\" height=\"200\"><\/a> This tombolo, called \"Angel Road,\" connects the stack of Shodo Island, Japan.[\/caption]\n\nIn [pb_glossary id=\"2289\"]emergent[\/pb_glossary] coasts, wave energy, wind, and gravity erode the [pb_glossary id=\"1968\"]coastline[\/pb_glossary]. The erosional features are elevated relative to the wave zone. Sea cliffs are persistent features as waves cut away at their base and higher rocks calve off by [pb_glossary id=\"2188\"]mass wasting[\/pb_glossary]. Refracted waves that attack [pb_glossary id=\"1023\"]bedrock[\/pb_glossary] at the base of headlands may erode or carve out a sea arch, which can extend below sea level in a sea cave. When a sea arch collapses, it leaves one or more rock columns called stacks.\n\n[caption id=\"attachment_3474\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/WaveCutPlatformsAntelopeIslandUT.jpg\"><img class=\"wp-image-779 size-medium\" title=\"By Wilson44691 [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-300x104.jpg\" alt=\"Wave notches carved by Lake Bonneville, Antelope Island, Utah.\" width=\"300\" height=\"104\"><\/a> Wave notches carved by Lake Bonneville, Antelope Island, Utah.[\/caption]A [pb_glossary id=\"2291\"]stack[\/pb_glossary] or near [pb_glossary id=\"2273\"]shore[\/pb_glossary] island creates a quiet water zone behind it.\u00a0 Sand moving in the [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary] accumulates in this quiet zone forming a <strong>[pb_glossary id=\"2292\"]tombolo[\/pb_glossary]<\/strong>: a sand strip that connects the island or [pb_glossary id=\"2291\"]stack[\/pb_glossary] to the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary]. Where sand supply is low, wave energy may erode a wave-cut [pb_glossary id=\"1260\"]platform[\/pb_glossary] across the [pb_glossary id=\"2276\"]surf zone[\/pb_glossary], exposed as bare rock with tidal pools at low [pb_glossary id=\"1480\"]tide[\/pb_glossary]. This bench-like [pb_glossary id=\"2240\"]terrace[\/pb_glossary] extends to the cliff\u2019s base. When wave energy cuts into the base of a sea cliff, it creates a [pb_glossary id=\"2294\"]wave notch[\/pb_glossary].\n\n&nbsp;\n\n[caption id=\"attachment_3475\" align=\"alignright\" width=\"354\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Chesapeakelandsat.jpeg\"><img class=\"wp-image-3475\" title=\"By Landsat\/NASA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Chesapeakelandsat.jpeg\" alt=\"The area is a filled-in river valleys.\" width=\"354\" height=\"266\"><\/a> Landsat image of Chesapeake Bay, eastern United States. Note the barrier islands parallel to the coastline.[\/caption]<strong>[pb_glossary id=\"2290\"]Submergent[\/pb_glossary] <\/strong>coasts occur where sea levels rise relative to land. This may be due to [pb_glossary id=\"1654\"]tectonic[\/pb_glossary] [pb_glossary id=\"511\"]subsidence[\/pb_glossary]\u2014when the Earth\u2019s [pb_glossary id=\"1658\"]crust[\/pb_glossary] sinks\u2014or when sea levels rise due to [pb_glossary id=\"1516\"]glacier[\/pb_glossary] melt. Features associated with [pb_glossary id=\"2290\"]submergent[\/pb_glossary] coasts include flooded [pb_glossary id=\"2212\"]river[\/pb_glossary] mouths, [pb_glossary id=\"2295\"]fjords[\/pb_glossary], [pb_glossary id=\"2296\"]barrier islands[\/pb_glossary], [pb_glossary id=\"1978\"]lagoons[\/pb_glossary], [pb_glossary id=\"2297\"]estuaries[\/pb_glossary], bays, [pb_glossary id=\"1975\"]tidal flats[\/pb_glossary], and tidal currents. In [pb_glossary id=\"2290\"]submergent[\/pb_glossary] coastlines, [pb_glossary id=\"2212\"]river[\/pb_glossary] mouths are flooded by the rising water, for example Chesapeake Bay. <strong>[pb_glossary id=\"2295\"]Fjords[\/pb_glossary]<\/strong> are [pb_glossary id=\"1988\"]glacial[\/pb_glossary] valleys flooded by post-[pb_glossary id=\"747\"]ice age[\/pb_glossary] sea level rise (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/14-glaciers\/\">Chapter 14<\/a>). [pb_glossary id=\"2296\"]Barrier islands[\/pb_glossary] are elongated bodies of sand that formed from old beach sands that used to parallel the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary]. Often, [pb_glossary id=\"1978\"]lagoons[\/pb_glossary] lie behind [pb_glossary id=\"2296\"]barrier islands[\/pb_glossary] <span class=\"FindHit BCX0 SCXW30978655\">[<\/span><span class=\"NormalTextRun BCX0 SCXW30978655\">3<\/span><span class=\"NormalTextRun BCX0 SCXW30978655\">]<\/span>. [pb_glossary id=\"2296\"]Barrier island[\/pb_glossary] [pb_glossary id=\"2038\"]formation[\/pb_glossary] is controversial: some scientists believe that they formed when [pb_glossary id=\"1519\"]ice sheets[\/pb_glossary] melted after the last [pb_glossary id=\"747\"]ice age[\/pb_glossary], raising sea levels. Another [pb_glossary id=\"1730\"]hypothesis[\/pb_glossary] is that [pb_glossary id=\"2296\"]barrier islands[\/pb_glossary] formed from spits and bars accumulating far [pb_glossary id=\"2274\"]offshore[\/pb_glossary].\n\n[caption id=\"attachment_3476\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tidal_flat_general_sketch-1.png\"><img class=\"wp-image-781 size-medium\" title=\"By Foxbat deinos \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-300x225.png\" alt=\"The tidal flat it a network of channels.\" width=\"300\" height=\"225\"><\/a> General diagram of a tidal flat and associated features.[\/caption]\n\n&nbsp;\n\n<strong>[pb_glossary id=\"1975\"]Tidal flats[\/pb_glossary]<\/strong>\u2014or mudflats<em>,<\/em> form where tides alternately flood and expose low areas along the [pb_glossary id=\"1968\"]coast[\/pb_glossary]. Tidal currents create combinations of symmetrical and asymmetrical [pb_glossary id=\"1946\"]ripple[\/pb_glossary] marks on mudflats, and drying mud creates mud cracks. In the central Wasatch Mountains of Utah, ancient [pb_glossary id=\"1975\"]tidal flat[\/pb_glossary] deposits are exposed in the [pb_glossary id=\"1270\"]Precambrian[\/pb_glossary] [pb_glossary id=\"1935\"]strata[\/pb_glossary] of the Big Cottonwood [pb_glossary id=\"2038\"]Formation[\/pb_glossary]. These ancient deposits provide an example of applying Hutton\u2019s [pb_glossary id=\"1736\"]principle of uniformitarianism[\/pb_glossary] (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/1-understanding-science\/\">Chapter 1<\/a>). Sedimentary structures common on modern [pb_glossary id=\"1975\"]tidal flats[\/pb_glossary] indicate that these ancient deposits were formed in a similar environment: there were [pb_glossary id=\"2273\"]shorelines[\/pb_glossary], tides, and shoreline processes acting at that time, yet the ancient age indicates that there were no land plants to hold products of [pb_glossary id=\"251\"]mechanical weathering[\/pb_glossary] in place (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>), so [pb_glossary id=\"1755\"]erosion[\/pb_glossary] rates would have been different.\n\nGeologically, [pb_glossary id=\"1975\"]tidal flats[\/pb_glossary] are broken into three different sections: barren zones, marshes, and salt pans. These zones may be present or absent in each individual [pb_glossary id=\"1975\"]tidal flat[\/pb_glossary]. Barren zones are areas with strong flowing water, coarser [pb_glossary id=\"1756\"]sediment[\/pb_glossary], with [pb_glossary id=\"1946\"]ripple[\/pb_glossary] marks and [pb_glossary id=\"1509\"]cross bedding[\/pb_glossary] common. Marshes are vegetated with sand and mud. Salt pans or flats, less often submerged than the other zones, are the finest-grained parts of [pb_glossary id=\"1975\"]tidal flats[\/pb_glossary], with silty [pb_glossary id=\"1756\"]sediment[\/pb_glossary] and mud cracks (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>)<span class=\"NormalTextRun BCX0 SCXW87010536\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW87010536\">[<\/span><span class=\"NormalTextRun BCX0 SCXW87010536\">4<\/span><span class=\"NormalTextRun BCX0 SCXW87010536\">]<\/span>.\n\n[caption id=\"attachment_3116\" align=\"alignright\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/LaggonKara_bogaz_gol.jpg\"><img class=\"wp-image-417 size-medium\" title=\"Source: Public domain, by NASA\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-300x300.jpg\" alt=\"The lagoon is just inside the coastline.\" width=\"300\" height=\"300\"><\/a> Kara-Bogaz Gol lagoon, Turkmenistan.[\/caption]\n\n<strong>[pb_glossary id=\"1978\"]Lagoons[\/pb_glossary]<\/strong> are locations where spits, [pb_glossary id=\"2296\"]barrier islands[\/pb_glossary]<em>,<\/em> or other features partially cut off a body of water from the ocean. <strong>[pb_glossary id=\"2297\"]Estuaries[\/pb_glossary]<\/strong> are a vegetated type of [pb_glossary id=\"1978\"]lagoon[\/pb_glossary] where fresh water flows into the area making the water [pb_glossary id=\"2298\"]brackish[\/pb_glossary]\u2014a salinity between salt and fresh water. However, terms like [pb_glossary id=\"1978\"]lagoon[\/pb_glossary], [pb_glossary id=\"2297\"]estuary[\/pb_glossary], and even bay are often loosely used in place of one another<span class=\"NormalTextRun BCX0 SCXW266504202\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW266504202\">[<\/span><span class=\"NormalTextRun BCX0 SCXW266504202\">5<\/span><span class=\"NormalTextRun BCX0 SCXW266504202\">]<\/span>. [pb_glossary id=\"1978\"]Lagoons[\/pb_glossary] and [pb_glossary id=\"2297\"]estuaries[\/pb_glossary] are certainly transitional between land and water environments where [pb_glossary id=\"1974\"]littoral[\/pb_glossary], shallow shorelines; [pb_glossary id=\"1983\"]lacustrine[\/pb_glossary], lakes or [pb_glossary id=\"1978\"]lagoons[\/pb_glossary]; and [pb_glossary id=\"1981\"]fluvial[\/pb_glossary], [pb_glossary id=\"2212\"]rivers[\/pb_glossary] or currents can overlap. For more information on [pb_glossary id=\"1978\"]lagoons[\/pb_glossary] and [pb_glossary id=\"2297\"]estuaries[\/pb_glossary], see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>.\n<h3><span style=\"font-weight: 400\">12.2.4 Human impact on coastal beaches<\/span><\/h3>\n[caption id=\"attachment_3477\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Groin_effect.jpg\"><img class=\"wp-image-782 size-medium\" title=\"By Archer0630\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-300x240.jpg\" alt=\"The sediment piled on one side and removed from the other.\" width=\"300\" height=\"240\"><\/a> Groins gathering sediment from longshore drift.[\/caption]\n\nHumans impact coastal beaches when they build homes, condominiums, hotels, businesses, and harbors\u2014and then again when they try to manage the natural processes of [pb_glossary id=\"1755\"]erosion[\/pb_glossary]. Waves, currents, [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary], and dams at [pb_glossary id=\"2212\"]river[\/pb_glossary] mouths deplete sand from expensive beachfront property and expose once calm harbors to high-wave energy. To protect their investment, keep sand on their beach, and maintain calm harbors, cities and landowners find ways to mitigate the damage by building [pb_glossary id=\"2287\"]jetties[\/pb_glossary], [pb_glossary id=\"2299\"]groins[\/pb_glossary], dams, and breakwaters.\n\n[caption id=\"attachment_3478\" align=\"alignright\" width=\"236\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096.jpg\"><img class=\"wp-image-783 size-medium\" title=\"By Internet Archive Book Images\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-236x300.jpg\" alt=\"Series of groins on a coast in Virginia\" width=\"236\" height=\"300\"><\/a> Groin system on a coast in Virginia[\/caption]\n\n[pb_glossary id=\"2287\"]Jetties[\/pb_glossary] are large manmade piles of boulders or concrete barriers built at [pb_glossary id=\"2212\"]river[\/pb_glossary] mouths and harbors. A [pb_glossary id=\"2287\"]jetty[\/pb_glossary] is designed to divert the current or [pb_glossary id=\"1480\"]tide[\/pb_glossary], to keep a channel to the ocean open, and to protect a harbor or beach from wave action. [pb_glossary id=\"2299\"]Groins[\/pb_glossary] are similar but smaller than [pb_glossary id=\"2287\"]jetties[\/pb_glossary]. [pb_glossary id=\"2299\"]Groins[\/pb_glossary] are fences of wire, wood or concrete built across the beach perpendicular to the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] and downstream of a property. Unlike [pb_glossary id=\"2287\"]jetties[\/pb_glossary], [pb_glossary id=\"2299\"]groins[\/pb_glossary] are used to preserve sand on a beach rather than to divert it. Sand erodes on the downstream side of the [pb_glossary id=\"2299\"]groin[\/pb_glossary] and collects against the upstream side. Every [pb_glossary id=\"2299\"]groin[\/pb_glossary] on one property thus creates a need for another one on the property downstream. A series of [pb_glossary id=\"2299\"]groins[\/pb_glossary] along a beach develops a scalloped appearance along the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary].\n\nInland [pb_glossary id=\"2212\"]streams[\/pb_glossary] and [pb_glossary id=\"2212\"]rivers[\/pb_glossary] flow to the ocean carrying sand to the [pb_glossary id=\"2283\"]longshore current[\/pb_glossary] which distributes it to beaches. When dams are built, they [pb_glossary id=\"2420\"]trap[\/pb_glossary] sand and keep [pb_glossary id=\"1756\"]sediment[\/pb_glossary] from reaching beaches. To replenish beaches, sand may be hauled in from other areas by trucks or barges and dumped on the depleted beach. Unfortunately, this can disrupt the ecosystem that exists along the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] by exposing [pb_glossary id=\"976\"]native[\/pb_glossary] creatures to foreign ecosystems and microorganisms and by introducing foreign objects to humans. For example, visitors to one replenished east [pb_glossary id=\"1968\"]coast[\/pb_glossary] beach found munitions and metal shards in the sand, which had been dredged from abandoned military test ranges<span class=\"NormalTextRun BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">[<\/span><span class=\"NormalTextRun BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">6]<\/span>.\n\n[caption id=\"attachment_3479\" align=\"alignright\" width=\"222\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped.jpg\"><img class=\"wp-image-784\" title=\"By Internet Archive Book Images\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-273x300.jpg\" alt=\"A tombolo formed behind the breakwater at Venice, CA\" width=\"222\" height=\"244\"><\/a> A tombolo formed behind the breakwater at Venice, CA[\/caption]\n\nAn approach to protect harbors and moorings from high-energy wave action is to build a <strong>[pb_glossary id=\"2301\"]breakwater[\/pb_glossary]<\/strong>\u2014an [pb_glossary id=\"2274\"]offshore[\/pb_glossary] structure against which the waves break, leaving calmer waters behind it. Unfortunately, breakwaters keep waves from reaching the beach and stop sand moving with [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary]. When [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary] is interrupted, sand is deposited in quieter water, and the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] builds out forming a [pb_glossary id=\"2292\"]tombolo[\/pb_glossary] behind the [pb_glossary id=\"2301\"]breakwater[\/pb_glossary]. The [pb_glossary id=\"2292\"]tombolo[\/pb_glossary] eventually fill in behind the [pb_glossary id=\"2301\"]breakwater[\/pb_glossary] with sand<span class=\"NormalTextRun BCX0 SCXW91600808\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW91600808\">[<\/span><span class=\"NormalTextRun BCX0 SCXW91600808\">7]<\/span>. When the city of Venice, California built a [pb_glossary id=\"2301\"]breakwater[\/pb_glossary] to create a quiet water harbor, [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary] created a [pb_glossary id=\"2292\"]tombolo[\/pb_glossary] behind the [pb_glossary id=\"2301\"]breakwater[\/pb_glossary], as seen in the image. The [pb_glossary id=\"2292\"]tombolo[\/pb_glossary] now acts as a large [pb_glossary id=\"2299\"]groin[\/pb_glossary] in the beach drift.\n<h3><span style=\"font-weight: 400\">12.2.5 Submarine Canyons <\/span><\/h3>\n[caption id=\"attachment_3480\" align=\"alignleft\" width=\"300\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Canyons_off_LA.jpg\"><img class=\"wp-image-785 size-medium\" title=\"By United States Geological Survey\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-300x213.jpg\" alt=\"The canyons are carved into the slope.\" width=\"300\" height=\"213\"><\/a> Submarine canyons off of Los Angeles. A=San Gabriel Canyon, B=Newport Canyon. At point C, the canyon is 815 m wide and 25 m deep.[\/caption]\n\n<strong>[pb_glossary id=\"2302\"]Submarine canyons[\/pb_glossary]<\/strong> are narrow, deep underwater canyons located on [pb_glossary id=\"1653\"]continental[\/pb_glossary] shelves. [pb_glossary id=\"2302\"]Submarine canyons[\/pb_glossary] typically form at the mouths of large landward [pb_glossary id=\"2212\"]river[\/pb_glossary] systems. They form when [pb_glossary id=\"2212\"]rivers[\/pb_glossary] cut down into the [pb_glossary id=\"1969\"]continental shelf[\/pb_glossary] during low sea level and when material continually slumps or flows down from the [pb_glossary id=\"1776\"]mouth[\/pb_glossary] of a [pb_glossary id=\"2212\"]river[\/pb_glossary] or a [pb_glossary id=\"1979\"]delta[\/pb_glossary]. Underwater currents rich in [pb_glossary id=\"1756\"]sediment[\/pb_glossary] and more dense than sea water, can flow down the canyons, even erode and deepen them, then drain onto the [pb_glossary id=\"1963\"]ocean floor[\/pb_glossary]. Underwater [pb_glossary id=\"246\"]landslides[\/pb_glossary], called <strong>[pb_glossary id=\"2303\"]turbidity flows[\/pb_glossary]<\/strong>, occur when steep [pb_glossary id=\"1979\"]delta[\/pb_glossary] faces and underwater [pb_glossary id=\"1756\"]sediment[\/pb_glossary] flows are released down the [pb_glossary id=\"1970\"]continental slope[\/pb_glossary]<span class=\"NormalTextRun BCX0 SCXW177996813\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW177996813\">[<\/span><span class=\"NormalTextRun BCX0 SCXW177996813\">8]<\/span>. [pb_glossary id=\"2303\"]Turbidity flows[\/pb_glossary] in submarine canyons can continue to erode the canyon, and eventually, fan-shaped deposits develop at the [pb_glossary id=\"1776\"]mouth[\/pb_glossary] of the canyon on the [pb_glossary id=\"1653\"]continental[\/pb_glossary] rise. See <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a> for more information on [pb_glossary id=\"2303\"]turbidity flows[\/pb_glossary].\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"86\"]\n\n[caption id=\"attachment_4710\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.2-Did-I-Get-It-QR-Code-1.png\"><img class=\"size-thumbnail wp-image-786\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 12.2 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">12.3\u00a0Currents and Tides<\/span><\/h2>\nOcean water moves as waves, currents, and tides. Ocean currents are driven by persistent global winds blowing over the water\u2019s surface and by water density. Ocean currents are part of Earth\u2019s heat engine in which solar energy is absorbed by ocean water and distributed by ocean currents. Water has another unique property, high specific heat, that relates to ocean currents. <strong>Specific heat<\/strong> is the amount of heat necessary to raise a unit volume of a substance one degree. For water it takes one calorie per cubic centimeter to raise its [pb_glossary id=\"1767\"]temperature[\/pb_glossary] one degree Celsius. This means the oceans, covering 71% of the Earth's surface, soak up solar heat with little [pb_glossary id=\"1767\"]temperature[\/pb_glossary] change and distribute that heat around the Earth by ocean currents.\n\n[caption id=\"attachment_3481\" align=\"aligncenter\" width=\"1000\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Corrientes-oceanicas.png\"><img class=\"wp-image-787 size-full\" title=\"By Dr. Michael Pidwirny\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas.png\" alt=\"Warm currents are red, blue currents are blue.\" width=\"1000\" height=\"522\"><\/a> World ocean currents.[\/caption]\n<h3><span style=\"font-weight: 400\">12.3.1 Surface Currents<\/span><\/h3>\nThe Earth\u2019s rotation and the Coriolis effect exert significant influence on ocean currents (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/13-deserts\/\">Chapter 13<\/a>). In the figure, the black arrows show global surface currents. Notice the large circular currents in the northern and southern hemispheres in the Atlantic, Pacific, and Indian Oceans. These currents are called <strong>[pb_glossary id=\"1478\"]gyres[\/pb_glossary]<\/strong> and are driven by atmospheric circulation\u2014air movement<span class=\"NormalTextRun BCX0 SCXW69864823\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW69864823\">[<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">9]<\/span>. [pb_glossary id=\"1478\"]Gyres[\/pb_glossary] rotate clockwise in the northern hemisphere and counterclockwise in the southern hemisphere because of the Coriolis Effect. Western boundary currents flow from the equator toward the poles carrying warm water. They are key contributors to local [pb_glossary id=\"757\"]climate[\/pb_glossary].\u00a0Western boundary currents are narrow and move poleward along the east coasts of adjacent continents. The Gulf [pb_glossary id=\"2212\"]Stream[\/pb_glossary] and the Kuroshio currents in the northern hemisphere and the Brazil, Mozambique, and Australian currents in the southern hemisphere are western boundary currents. Currents returning cold water toward the equator are broad and diffuse along the western coasts of adjacent land masses. These warm western boundary and cold eastern boundary currents affect [pb_glossary id=\"757\"]climate[\/pb_glossary] of nearby lands making them warmer or colder than other areas at equivalent latitudes. For example, the warm Gulf [pb_glossary id=\"2212\"]Stream[\/pb_glossary] makes Northern Europe much milder than similar latitudes in northeastern Canada and Greenland. Another example is the cool Humboldt Current, also called the Peru Current, flowing north along the west [pb_glossary id=\"1968\"]coast[\/pb_glossary] of South America. Cold currents limit evaporation in the ocean, which is one reason the [pb_glossary id=\"1492\"]Atacama Desert[\/pb_glossary] in Chile is cool and arid<span class=\"NormalTextRun BCX0 SCXW69864823\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW69864823\">[<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">10<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">]<\/span>.\n<h3><span style=\"font-weight: 400\">12.3.2 Deep Currents<\/span><\/h3>\n[caption id=\"attachment_3482\" align=\"alignleft\" width=\"442\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Thermohaline_Circulation.png\"><img class=\"wp-image-788\" title=\"By Robert Simmon, NASA. Minor modifications by Robert A. Rohde also released to the public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-300x188.png\" alt=\"In certain areas, the current sinks or rises.\" width=\"442\" height=\"277\"><\/a> Global thermohaline circulation. PSS=practical salinity units.[\/caption]\n\nWhether an ocean current moves horizontally or vertically depends on its density. The density of seawater is determined by [pb_glossary id=\"1767\"]temperature[\/pb_glossary] and salinity.\n\nEvaporation and freshwater influx from [pb_glossary id=\"2212\"]rivers[\/pb_glossary] affect salinity and, therefore, the density of seawater. As the western boundary currents cool at high latitudes and salinity increases due to evaporation and ice [pb_glossary id=\"2038\"]formation[\/pb_glossary] (recall that ice floats; water is densest just above its freezing point). So the cold, denser water sinks to become the ocean\u2019s deep waters. Deep-water movement is called <strong>[pb_glossary id=\"1479\"]thermohaline circulation[\/pb_glossary]<\/strong>\u2014<em>thermo <\/em>refers to [pb_glossary id=\"1767\"]temperature[\/pb_glossary], and <em>haline <\/em>refers to salinity. This circulation connects the world\u2019s deep ocean waters. Movement of the Gulf [pb_glossary id=\"2212\"]Stream[\/pb_glossary] illustrates the beginning of [pb_glossary id=\"1479\"]thermohaline circulation[\/pb_glossary]. Heat in the warm poleward moving Gulf [pb_glossary id=\"2212\"]Stream[\/pb_glossary] promotes\u00a0 evaporation which takes heat from the water and as heat thus dissipates, the water cools. The resulting water is much colder, saltier, and denser. As the denser water reaches the North Atlantic and Greenland, it begins to sink and becomes a deep-water current. As shown in the illustration above, this worldwide connection between shallow and deep-ocean circulation overturns and mixes the entire world ocean, bringing nutrients to [pb_glossary id=\"1961\"]marine[\/pb_glossary] life, and is sometimes referred to as the <strong>[pb_glossary id=\"1479\"]global conveyor belt[\/pb_glossary]<\/strong><span class=\"NormalTextRun BCX0 SCXW9267996\">\u00a0<\/span><strong><span class=\"FindHit BCX0 SCXW9267996\">[<\/span><span class=\"NormalTextRun BCX0 SCXW9267996\">11]<\/span><\/strong>.\n<h3><span style=\"font-weight: 400\">12.3.3 Tides<\/span><\/h3>\n<strong>Tides<\/strong> are the rising and lowering of sea level during the day and are caused by the gravitational effects of the Sun and Moon on the oceans<span class=\"NormalTextRun BCX0 SCXW65683472\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW65683472\">[<\/span><span class=\"NormalTextRun BCX0 SCXW65683472\">12]<\/span>. The Earth rotates daily within the Moon and Sun\u2019s gravity fields. Although the Sun is much larger and its gravitational pull is more powerful, the Moon is closer to Earth; hence, the Moon\u2019s gravitational influence on tides is dominant. The [pb_glossary id=\"2176\"]magnitude[\/pb_glossary] of the [pb_glossary id=\"1480\"]tide[\/pb_glossary] at a given location and the difference between high and low [pb_glossary id=\"1480\"]tide[\/pb_glossary]\u2014the tidal range, depends primarily on the configuration of the Moon and Sun with respect to the Earth orbit and rotation. <strong>[pb_glossary id=\"1481\"]Spring tide[\/pb_glossary]<\/strong> occurs when the Sun, Moon, and Earth line up with each other at the full or new Moon, and the tidal range is at a maximum. <strong>[pb_glossary id=\"1482\"]Neap tide[\/pb_glossary]<\/strong> occurs approximately two weeks later when the Moon and Sun are at right angles with the Earth, and the tidal range is lowest.\n\n<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tide_schematic.svg_.png\"><img class=\"alignright wp-image-789 size-medium\" title=\"By User:KVDP, SVG conversion by Surachit\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-300x168.png\" alt=\"\" width=\"300\" height=\"168\"><\/a>\n\n[caption id=\"attachment_3484\" align=\"alignleft\" width=\"198\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tide_type.svg_.png\"><img class=\"wp-image-790 size-medium\" title=\"By Snubcube (Own work) \" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-198x300.png\" alt=\"Each tide has a different curve.\" width=\"198\" height=\"300\"><\/a> Different tide types[\/caption]\n\nThe Earth rotates within a tidal envelope, so tides rise and ebb daily. Tides are measured at coastal locations. These measurements and the tidal predictions based on them are published on the <a href=\"https:\/\/tidesandcurrents.noaa.gov\/tide_predictions.html\">NOAA website <\/a><span class=\"FindHit BCX0 SCXW77792513\">[<\/span><span class=\"NormalTextRun BCX0 SCXW77792513\">13].<\/span> Tides rising and falling create tidal patterns at any given [pb_glossary id=\"2273\"]shore[\/pb_glossary] location. The three types of tidal patterns are <em>diurnal,<\/em> <em>semidiurnal,<\/em> and <em>mixed<strong>.<\/strong><\/em>\n\n[caption id=\"attachment_3485\" align=\"alignright\" width=\"455\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Diurnal_tide_types_map.jpg\"><img class=\"wp-image-791\" title=\"By KVDP (Own work) [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-300x147.jpg\" alt=\"The map shows locations of the different tide types.\" width=\"455\" height=\"224\"><\/a> Global tide types[\/caption]<strong>[pb_glossary id=\"1483\"]Diurnal tides[\/pb_glossary]<\/strong> go through one complete cycle each [pb_glossary id=\"1484\"]tidal day[\/pb_glossary]. A <strong>[pb_glossary id=\"1484\"]tidal day[\/pb_glossary]<\/strong> is the amount of time for the Moon to align with a point on the Earth as the Earth rotates, which is slightly longer than 24 hours. <strong>Semidiurnal<\/strong> tides go through two complete cycles in each [pb_glossary id=\"1484\"]tidal day[\/pb_glossary]\u2014approximately 12 hours and 50 minutes, with the tidal range typically varying in each cycle. <strong>Mixed<\/strong> tides are a combination of diurnal and semidiurnal patterns and show two tidal cycles per [pb_glossary id=\"1484\"]tidal day[\/pb_glossary], but the relative amplitudes of each cycle and their highs and lows vary during the tidal month. For example, there is a high, high [pb_glossary id=\"1480\"]tide[\/pb_glossary] and a high, low [pb_glossary id=\"1480\"]tide[\/pb_glossary]. The next day, there is a low, high [pb_glossary id=\"1480\"]tide[\/pb_glossary] and a low, low [pb_glossary id=\"1480\"]tide[\/pb_glossary]. Forecasting the tidal pattern and the times tidal phases arrive at a given [pb_glossary id=\"2273\"]shore[\/pb_glossary] location\n\n[caption id=\"attachment_3486\" align=\"alignright\" width=\"281\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/12.3_Lunar_Day_Tide.gif\"><img class=\"size-medium wp-image-792\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3_Lunar_Day_Tide-281x300.gif\" alt=\"GIF animation showing Earth rotating and tides fluctuating as a result of lunar gravitational forces.\" width=\"281\" height=\"300\"><\/a> A tidal day lasts slightly longer than 24 hours. Source:[\/caption]\n\nis complicated and can be done for only a few days at a time. Tidal phases are determined by <em>bathymetry:<\/em> the depth of ocean basins and the [pb_glossary id=\"1653\"]continental[\/pb_glossary] obstacles that are in the way of the tidal envelope within which the Earth rotates. Local tidal experts make 48-hour tidal forecasts using tidal charts based on daily observations, as can be seen in the chart of different [pb_glossary id=\"1480\"]tide[\/pb_glossary] types. A typical tidal range is approximately 1 m (3 ft). Extreme tidal ranges occur where the tidal wave enters a narrow restrictive zone that funnels the tidal energy. An example is the English Channel between Great Britain and the European [pb_glossary id=\"1653\"]continent[\/pb_glossary] where the tidal range is 7 to 9.75 m (23 to 32 ft). The Earth\u2019s highest tidal ranges occur at the Bay of Fundy, the funnel-like bay between Nova Scotia and New Brunswick, Canada, where the average range is nearly 12 m (40 ft) and the extreme range is around 18 m (60 ft). At extreme tidal range locations, a person who ventures out onto the seafloor exposed during ebb [pb_glossary id=\"1480\"]tide[\/pb_glossary] may not be able to outrun the advancing water during flood [pb_glossary id=\"1480\"]tide[\/pb_glossary]. <a href=\"https:\/\/www.co-ops.nos.noaa.gov\/faq2.html#26\">NOAA<\/a> has additional information on tides.\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n[h5p id=\"87\"]\n\n[caption id=\"attachment_4711\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.3-Did-I-Get-It-QR-Code-1.png\"><img class=\"size-thumbnail wp-image-793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the quiz for section 12.3 via this QR Code.[\/caption]\n<h2>Summary<\/h2>\n[pb_glossary id=\"2273\"]Shoreline[\/pb_glossary] processes are complex, but important for understanding coastal processes. Waves, currents, and tides are the main agents that shape shorelines. Most coastal landforms can be attributed to moving sand via [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary], and long-term rising or falling sea levels.\n\nThe [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] is the interface between water and land and is divided into five zones. Processes at the [pb_glossary id=\"2273\"]shoreline[\/pb_glossary] are called [pb_glossary id=\"1974\"]littoral[\/pb_glossary] processes. Waves approach the beach at an angle, which cause the waves to bend towards the beach. This bending action is called [pb_glossary id=\"2169\"]wave refraction[\/pb_glossary] and is responsible for creating the [pb_glossary id=\"2283\"]longshore current[\/pb_glossary] and [pb_glossary id=\"2284\"]longshore drift[\/pb_glossary]\u2014the process that moves sand along the coasts. When the [pb_glossary id=\"2283\"]longshore current[\/pb_glossary] deposits sand along the [pb_glossary id=\"1968\"]coast[\/pb_glossary] into quieter waters, the sand can accumulate, creating a [pb_glossary id=\"2285\"]spit[\/pb_glossary] or barrier called a [pb_glossary id=\"2286\"]baymouth bar[\/pb_glossary], which often blocks bays and harbors. Inconvenienced humans create methods to keep their harbors open and preserve sand on their beaches by creating [pb_glossary id=\"2287\"]jetties[\/pb_glossary] and [pb_glossary id=\"2299\"]groins[\/pb_glossary], which negatively affect natural beach processes.\n\n[pb_glossary id=\"2289\"]Emergent[\/pb_glossary] coasts are created by sea levels falling, while [pb_glossary id=\"2290\"]submergent[\/pb_glossary] coasts are caused by sea levels rising. Oceans absorb solar energy, which is distributed by currents throughout the world. Circular surface currents, called [pb_glossary id=\"1478\"]gyres[\/pb_glossary], rotate clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. Thermohaline deep circulation connects the world\u2019s deep ocean waters: when shallow poleward moving warm water evaporates, the colder, saltier, and denser water sinks and becomes deep-water currents. The connection between shallow and deep-ocean circulation is called the [pb_glossary id=\"1479\"]global conveyor belt[\/pb_glossary].\n\nTides are the rising and lowering of sea level during the day and are caused by the gravitational effects of the Sun and Moon on the oceans. There are three types of tidal patterns: diurnal, semidiurnal, and mixed. Typical tidal ranges are approximately 1 m (3 ft). Extreme tidal ranges are around 18 m (60 ft).\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n[h5p id=\"88\"]\n\n[caption id=\"attachment_4708\" align=\"aligncenter\" width=\"150\"]<a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Ch.12-Review-QR-Code-1.png\"><img class=\"size-thumbnail wp-image-794\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\"><\/a> If you are using the printed version of this OER, access the review quiz for Chapter 12 via this QR Code.[\/caption]\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<ol>\n \t<li><span style=\"color: #000000\">Colling, Angela. 2001. <em>Ocean Circulation<\/em>. Edited by Open University Course Team. Butterworth-Heinemann.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Davis, Richard A., Jr., and Duncan M. Fitzgerald. 2009. <em>Beaches and Coasts<\/em>. John Wiley &amp; Sons.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Davis, Richard Albert. 1997. <em>The Evolving Coast<\/em>. Scientific American Library New York.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Greene, Paul, George Follett, and Clint Henker. 2009. \u201cMunitions and Dredging Experience on the United States Coast.\u201d <em>Marine Technology Society Journal<\/em> 43 (4): 127\u201331.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Jackson, Nancy L., Mitchell D. Harley, Clara Armaroli, and Karl F. Nordstrom. 2015. \u201cBeach Morphologies Induced by Breakwaters with Different Orientations.\u201d <em>Geomorphology <\/em>\u00a0239 (June). Elsevier: 48\u201357.<\/span><\/li>\n \t<li><span style=\"color: #000000\">\u201cLittoral Bypassing and Beach Restoration in the Vicinity of Port Hueneme, California.\u201d n.d. In <em>Coastal Engineering 1966<\/em>.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Munk, Walter H. 1950. \u201cON THE WIND-DRIVEN OCEAN CIRCULATION.\u201d <em>Journal of Meteorology<\/em> 7 (2): 80\u201393.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Normark, William R., and Paul R. Carlson. 2003. \u201cGiant Submarine Canyons: Is Size Any Clue to Their Importance in the Rock Record?\u201d <em>Geological Society of America Special Papers<\/em> 370 (January): 175\u201390.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Reineck, H-E, and Indra Bir Singh. 2012. <em>Depositional Sedimentary Environments: With Reference to Terrigenous Clastics<\/em>. Springer Science &amp; Business Media.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Rich, John Lyon. 1951. \u201cTHREE CRITICAL ENVIRONMENTS OF DEPOSITION, AND CRITERIA FOR RECOGNITION OF ROCKS DEPOSITED IN EACH OF THEM.\u201d <em>Geological Society of America Bulletin<\/em> 62 (1). gsabulletin.gsapubs.org: 1\u201320.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Runyan, Kiki, and Gary Griggs. 2005. \u201cImplications of Harbor Dredging for the Santa Barbara Littoral Cell.\u201d In <em>California and the World Ocean \u201902<\/em>, 121\u201335. Reston, VA: American Society of Civil Engineers.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Schwiderski, Ernst W. 1980. \u201cOn Charting Global Ocean Tides.\u201d <em>Reviews of Geophysics <\/em>\u00a018 (1): 243\u201368.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Stewart, Robert H. 2008. <em>Introduction to Physical Oceanography<\/em>. Texas A &amp; M University Texas.<\/span><\/li>\n \t<li><span style=\"color: #000000\">Stommel, Henry, and A. B. Arons. 2017. \u201cOn the Abyssal Circulation of the World ocean\u2014I. Stationary Planetary Flow Patterns on a Sphere - ScienceDirect.\u201d Accessed February 26. <a href=\"http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656<\/a><a style=\"color: #000000\" href=\"https:\/\/urldefense.com\/v3\/__http:\/paperpile.com\/b\/g9x6vx\/VZcZ__;!!NfSqYQ!Vzpmk-s8-k4BNbewuxNNSWTdb45bEiMshN29wwvaDKS0yaTfNqoMN6swSO17i9oKkw$\">.<\/a><\/span><\/li>\n \t<li><span style=\"color: #000000\">Stommel, Henry, and A. B. Arons. 2017. \u201cOn the Abyssal Circulation of the World ocean\u2014I. Stationary Planetary Flow Patterns on a Sphere - ScienceDirect.\u201d Accessed February 26. <a href=\"http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656<\/a>.<\/span><\/li>\n<\/ol>\n&nbsp;","rendered":"<figure id=\"attachment_3461\" aria-describedby=\"caption-attachment-3461\" style=\"width: 873px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/PP3.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-766\" title=\"By Matt Affolter\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-300x225.jpg\" alt=\"The beach is over sunset.\" width=\"873\" height=\"655\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-300x225.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-1024x768.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-768x576.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-1536x1152.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-65x49.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-225x169.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3-350x263.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2021\/12\/PP3.jpg 2048w\" sizes=\"auto, (max-width: 873px) 100vw, 873px\" \/><\/a><figcaption id=\"caption-attachment-3461\" class=\"wp-caption-text\">Sunset over the coastline of Puerto Pe\u00f1asco, M\u00e9xico. Because of the narrow Gulf of California, Puerto Pe\u00f1asco has one of the largest tidal ranges in western North America.<\/figcaption><\/figure>\n<h1>12 Coastlines<\/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>Describe how waves occur, move, and carry energy<\/li>\n<li>Explain wave behavior approaching the shoreline<\/li>\n<li>Describe shoreline features and zones<\/li>\n<li>Describe wave refraction and its contribution to longshore currents and longshore drift<\/li>\n<li>Explain how longshore currents cause the formation of spits and baymouth bars<\/li>\n<li>Distinguish between submergent and emergent coasts and describe coastal features associated with each<\/li>\n<li>Describe the relationship between the natural river of sand in the littoral zone and human attempts to alter it for human convenience<\/li>\n<li>Describe the pattern of the main ocean currents and explain the different factors involved in surface currents and deep ocean currents<\/li>\n<li>Explain how ocean tides occur and distinguish among diurnal, semidiurnal, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1486\">mixed tide<\/a> patterns<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li style=\"list-style-type: none\"><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>The Earth\u2019s surface is 29% land and 71% water. Coastlines are the interfaces between, and as such, the longest visible boundaries on Earth. To understand the processes that occur at these boundaries, it is important to first understand wave energy.<\/p>\n<h2><span style=\"font-weight: 400\">12.1 Waves and Wave Processes<\/span><\/h2>\n<figure id=\"attachment_3462\" aria-describedby=\"caption-attachment-3462\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Deep_water_wave.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-767 size-medium\" title=\"By Kraaiennest (Own work)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-300x197.gif\" alt=\"The particles move in roughly circular motion.\" width=\"300\" height=\"197\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-300x197.gif 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-65x43.gif 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-225x148.gif 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Deep_water_wave-350x230.gif 350w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3462\" class=\"wp-caption-text\">Particle motion within a wind-blown wave.<\/figcaption><\/figure>\n<p>Wind blowing over the surface of water transfers energy to the water through friction. The energy transferred from wind to water causes waves to form. Waves move as individual oscillating particles of water. As the wave crest passes, the water is moving forward. As the wave trough passes, the water is moving backward. To see wave movement in action, watch a cork or some floating object as a wave passes.<\/p>\n<p><span style=\"font-weight: 400\">\u00a0<\/span><\/p>\n<figure id=\"attachment_3463\" aria-describedby=\"caption-attachment-3463\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Water_wave_diagram.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-768 size-medium\" title=\"By NOAA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-300x152.jpg\" alt=\"Crest, trough, period, wavelength are labeled.\" width=\"300\" height=\"152\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-300x152.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-65x33.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-225x114.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram-350x177.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Water_wave_diagram.jpg 600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3463\" class=\"wp-caption-text\">Aspects of water waves, labeled.<\/figcaption><\/figure>\n<p>Important terms to understand in the operation of waves include: the <strong>wave crest<\/strong> is the highest point of the wave; the <strong>trough<\/strong> is the lowest point of the wave. <strong>Wave height <\/strong>is the vertical distance from the trough to the crest and is determined by wave energy. W<strong>ave amplitude <\/strong>is half the wave height, or the distance from either the crest or trough to the still water line. <strong>Wavelength<\/strong> is the horizontal distance between consecutive wave crests. <strong>Wave velocity<\/strong> is the speed at which a wave crest moves forward and is related to the wave\u2019s energy. <strong>Wave period<\/strong> is the time interval it takes for adjacent wave crests to pass a given point.<\/p>\n<figure id=\"attachment_3097\" aria-describedby=\"caption-attachment-3097\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Wavebase.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-408 size-medium\" title=\"https:\/\/en.wikipedia.org\/wiki\/File:Wavebase.jpg, by https:\/\/en.wikipedia.org\/wiki\/User:GregBenson: Permission is granted to copy, distribute and\/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-300x218.jpg\" alt=\"The diagram shows that wavebase is 1\/2 the wavelength of waves of water.\" width=\"300\" height=\"218\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-300x218.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-65x47.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-225x164.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase-350x255.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wavebase.jpg 400w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3097\" class=\"wp-caption-text\">Diagram describing wavebase.<\/figcaption><\/figure>\n<p>The circular motion of water particles diminishes with depth and is negligible at about one-half wavelength, an important dimension to remember in connection with waves. <strong>Wave base<\/strong> is the vertical depth at which water ceases to be disturbed by waves. In water shallower than wave base, waves will disturb the bottom and ripple shore sand. Wave base is measured at a depth of about one-half wavelength, where the water particles\u2019 circular motion diminishes to zero. If waves approaching a beach have crests at about 6 m (~20 ft) intervals, this wave motion disturbs water to about 3 m (~10 ft) deep. This motion is known as f<strong>air-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_756\">weather<\/a> wave base<\/strong>. In strong storms such as hurricanes, both wavelength and wave base increase dramatically to a depth known as <strong>storm wave base<\/strong>, which is approximately 91 m (~300 ft) <span class=\"FindHit BCX0 SCXW110913762\">[<\/span><span class=\"NormalTextRun BCX0 SCXW110913762\">1]<\/span>.<\/p>\n<p>Waves are generated by wind blowing across the ocean surface. The amount of energy imparted to the water depends on wind velocity and the distance across which the wind is blowing. This distance is called <strong>fetch<\/strong>. Waves striking a shore are typically generated by storms hundreds of miles from the coast and have been traveling across the ocean for days.<\/p>\n<figure id=\"attachment_3464\" aria-describedby=\"caption-attachment-3464\" style=\"width: 200px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Wave_packet_dispersion.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-769 size-full\" title=\"By Fffred~commonswiki\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Wave_packet_dispersion.gif\" alt=\"The wave moves across the image.\" width=\"200\" height=\"115\" \/><\/a><figcaption id=\"caption-attachment-3464\" class=\"wp-caption-text\">Wave train moving with dispersion.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Winds blowing in a relatively constant direction generate waves moving in that direction. Such a group of approximately parallel waves traveling together is called a <strong>wave train<\/strong>.\u00a0 A wave train coming from one fetch can produce various wavelengths. Longer wavelengths travel at a faster velocity than shorter wavelengths, so they arrive first at a distant shore. Thus, there is a wavelength&#8211;sorting process that takes place during the wave train\u2019s travel. This sorting process is called <strong>wave dispersion<\/strong>.<\/p>\n<p><b style=\"font-size: 23px\">1<\/b><b style=\"font-size: 23px\">2.1.1 Behavior of Waves Approaching Shore<\/b><\/p>\n<figure id=\"attachment_3465\" aria-describedby=\"caption-attachment-3465\" style=\"width: 238px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Breaking_wave_types.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-770 size-medium\" title=\"By Kraaiennest\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-238x300.png\" alt=\"There are four types of breakers\" width=\"238\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-238x300.png 238w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-812x1024.png 812w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-768x968.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-65x82.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-225x284.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_-350x441.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Breaking_wave_types.svg_.png 952w\" sizes=\"auto, (max-width: 238px) 100vw, 238px\" \/><\/a><figcaption id=\"caption-attachment-3465\" class=\"wp-caption-text\">Types of breakers<\/figcaption><\/figure>\n<p>On the open sea, waves generally appear choppy because wave trains from many directions are interacting with each other, a process called wave interference. Constructive interference occurs where crests align with other crests. The aligned wave height is the sum of the individual wave heights, a process referred to as <em>wave amplification.<\/em> Constructive interference also produces hollows where troughs align with other troughs. Destructive interference occurs where crests align with troughs and cancel each other out. As waves approach shore and begin to make frictional contact with the sea floor at a depth of about one-half wavelength or less, they begin to slow down. However, the energy carried by the wave remains the same, so the waves build up higher. Remember that water moves in a circular motion as a wave passes, and each circle is fed from the trough in front of the advancing wave. As the wave encounters shallower water at the shore, there is eventually insufficient water in the trough in front of the wave to supply a complete circle, so the crest pours over creating a <strong>breaker<\/strong>.<\/p>\n<figure id=\"attachment_3466\" aria-describedby=\"caption-attachment-3466\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Propagation_du_tsunami_en_profondeur_variable.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-771 size-medium\" title=\"By R\u00e9gis Lachaume (Own work)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-300x157.gif\" alt=\"The waves get taller in shallow water.\" width=\"300\" height=\"157\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-300x157.gif 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-65x34.gif 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-225x118.gif 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Propagation_du_tsunami_en_profondeur_variable-350x184.gif 350w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3466\" class=\"wp-caption-text\">All waves, like tsunamis, slow down as they reach shallow water. This causes the wave to increase in hight.<\/figcaption><\/figure>\n<p>A special type of wave is called a <strong>tsunami,<\/strong> sometimes incorrectly called a \u00ab\u00a0tidal wave.\u00a0\u00bb Tsunamis are generated by energetic events affecting the sea floor, such as earthquakes, submarine <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_246\">landslides<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_228\">volcanic<\/a> eruptions (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/9-crustal-deformation-and-earthquakes\/\">Chapter 9<\/a> and <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/4-igneous-processes-and-volcanoes\/\">Chapter 4<\/a>). During earthquakes for example, tsunamis can be produced when the moving crustal rocks below the sea abruptly elevate a portion of the seafloor. Water is suddenly lifted creating a bulge at the surface and a wave train spreads out in all directions traveling at tremendous speeds [over 322 kph (200 mph)] and carrying enormous energy. Tsunamis may pass unnoticed in the open ocean because they move so fast, the wavelength is very long, and the wave height is very low. But, as the wave train approaches shore and each wave begins to interact with the shallow seafloor, friction increases and the wave slows down. Still carrying its enormous energy, wave height builds up and the wave strikes the shore as a wall of water that can be over 30 m (~100 ft)\u00a0 high. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_985\">massive<\/a> wave, called a tsunami runup, may sweep inland well beyond the beach destroying structures far inland. Tsunamis can deliver a catastrophic blow to people at the beach. As the trough water in front of the tsunami wave is drawn back, the seafloor is exposed. Curious and unsuspecting people on the beach may run out to see exposed offshore sea life only to be overwhelmed when the breaking crest hits.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-85\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-85\" class=\"h5p-iframe\" data-content-id=\"85\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"12.1 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4709\" aria-describedby=\"caption-attachment-4709\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.1-Did-I-Get-It-QR-Code-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-772\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.1-Did-I-Get-It-QR-Code-1.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4709\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 12.1 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">12.2 Shoreline Features<\/span><\/h2>\n<p><strong>Coastlines<\/strong> are dynamic, high energy, and geologically complicated places where many different erosional and depositional features exist (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>). They include all parts of the land-sea boundary directly affected by the sea, including land far above high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> and seafloor well below normal wave base. But, the<strong> shoreline<\/strong> itself is the direct interface between water and land that shifts with the tides. This shifting interface at the shoreline is called the<strong> littoral<\/strong> zone. The combination of waves, currents, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_757\">climate<\/a>, coastal morphology, and gravity, all act on this land-sea boundary to create shoreline features.<\/p>\n<h3><strong>12.2.1 Shoreline Zones<\/strong><\/h3>\n<figure id=\"attachment_3467\" aria-describedby=\"caption-attachment-3467\" style=\"width: 441px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Littoral_Zones-1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-409\" title=\"US Navy, [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1.jpg\" alt=\"The image shows the many complexities of the shoreline described in the text.\" width=\"441\" height=\"193\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1.jpg 666w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1-300x132.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1-65x28.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1-225x99.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Littoral_Zones-1-350x153.jpg 350w\" sizes=\"auto, (max-width: 441px) 100vw, 441px\" \/><\/a><figcaption id=\"caption-attachment-3467\" class=\"wp-caption-text\">Diagram of zones of the shoreline.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>Shorelines are divided into five primary zones\u2014offshore, nearshore, surf, foreshore, and backshore. The <strong>offshore<\/strong> zone is below water, but it is still geologically active due to flows of turbidity currents that cascade over the continental slope and accumulate in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1653\">continental<\/a> rise. The <strong>nearshore<\/strong> zone is the area of the shore affected by the waves where water depth is one-half wavelength or less. The width of this zone depends on the maximum wavelength of the approaching wave train and the slope of the seafloor. The nearshore zone includes the <strong>shoreface<\/strong>, which is where sand is disturbed and deposited. The shoreface is broken into two segments: upper and lower shoreface. Upper shoreface is affected by everyday wave action and consists of finely-laminated and cross-bedded sand. The lower shoreface is the only area moved by storm waves and consists of hummocky cross-stratified sand. The <strong>surf zon<\/strong>e is where the waves break.<\/p>\n<p>The <strong>foreshore<\/strong> zone overlaps the surf zone and is periodically wet and dry due to waves and tides. The foreshore zone is where planer-laminated, well-sorted sand accumulates. The beach face is the part of the foreshore zone where the breaking waves swash up and the backwash flows back down. Low ridges above the beach face in the foreshore zone are called berms. During the summer in North America, when most people visit the beach, the zone where people spread their towels and beach umbrellas is the <strong>summer berm<\/strong>. Wave energy is typically lower in the summer, which allows sand to pile onto the beach. Behind the summer berm is a low ridge of sand called the <strong>winter berm<\/strong><em>.<\/em> In winter, higher storm energy moves the summer berm sand off the beach and piles it in the nearshore zone. The next year, that sand is replaced on the beach and moved back onto the summer berm. The <strong>backshore<\/strong> zone is the area always above sea level in normal conditions. In the backshore zone<em>,<\/em> onshore winds may blow sand behind the beach and the berms, creating dunes.<\/p>\n<h3><b>12.2.2 Refraction, Longshore Currents, and Longshore Drift<\/b><\/h3>\n<figure id=\"attachment_3468\" aria-describedby=\"caption-attachment-3468\" style=\"width: 195px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Longshore.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-773 size-medium\" title=\"By USGS\/USGov, modified by Eurico Zimbres [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-195x300.png\" alt=\"The waves move sand along the beach.\" width=\"195\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-195x300.png 195w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-65x100.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-225x347.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore-350x539.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Longshore.png 653w\" sizes=\"auto, (max-width: 195px) 100vw, 195px\" \/><\/a><figcaption id=\"caption-attachment-3468\" class=\"wp-caption-text\">Longshore Drift. 1=beach, 2=sea, 3=longshore current direction, 4=incoming waves, 5=swash, 6=backwash<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p>As waves enter shallower water less than one-half wavelength depth, they slow down. Waves usually approach the shoreline at an angle, with the end of the waves nearest the beach slowing down first. This causes the wave crests to bend,\u00a0 called <strong>wave refraction<\/strong>. From the beach face, this causes it to look like waves are approaching the beach straight on, parallel to the beach. However, as refracted waves actually approach the shoreline at a slight angle, they create a slight difference between the swash as it moves up the beach face at a slight angle and the backwash as it flows straight back down under gravity. This slight angle between swash and backwash along the beach creates a current called the l<strong>ongshore current<\/strong>. Waves stir up sand in the surf zone and move it along the shore. This movement of sand is called <strong>longshore drift<\/strong>. Longshore drift along both the west and east coasts of North America moves sand north to south on average.<\/p>\n<figure id=\"attachment_3469\" aria-describedby=\"caption-attachment-3469\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/FarewellSpitNZ.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-774 size-medium\" title=\"By NASA\/GSFC\/METI\/ERSDAC\/JAROS, and U.S.\/Japan ASTER Science Team (NASA's Earth Observatory) [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-300x193.jpg\" alt=\"The spit is a long ridge of sand\" width=\"300\" height=\"193\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-300x193.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-1024x659.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-768x494.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-1536x989.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-65x42.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-225x145.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ-350x225.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/FarewellSpitNZ.jpg 1600w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3469\" class=\"wp-caption-text\">Farewell Spit, New Zealand<\/figcaption><\/figure>\n<p>Longshore currents can carry longshore drift down a coast until it reaches a bay or inlet where it will deposit sand in the quieter water (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/11-water\/\">Chapter 11<\/a>). Here, a <strong>spit<\/strong> can form. As the spit grows, it may extend across the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a> of the bay forming a barrier called a <strong>baymouth bar<\/strong>. Where the bay or inlet serves as boat anchorage, spits and baymouth bars are a severe inconvenience. Often, inconvenienced communities create methods to keep their bays and harbors open<span style=\"font-weight: 400\">.<\/span><\/p>\n<figure id=\"attachment_3470\" aria-describedby=\"caption-attachment-3470\" style=\"width: 295px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Jetty.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-775 size-full\" title=\"USGS, public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Jetty.jpg\" alt=\"The two jetties led to a coastal waterway.\" width=\"295\" height=\"197\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Jetty.jpg 295w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Jetty-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Jetty-225x150.jpg 225w\" sizes=\"auto, (max-width: 295px) 100vw, 295px\" \/><\/a><figcaption id=\"caption-attachment-3470\" class=\"wp-caption-text\">Jetties near Carlsbad, California. Notice the left jetty is loaded with sand, while the right jetty is lacking sand. This is due to the longshore drift going left to right.<\/figcaption><\/figure>\n<p>One way to keep a harbor open is to build a <strong>jetty,<\/strong> a long concrete or stone barrier constructed to deflect the sand away from a harbor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a> or other ocean waterway. If the jetty does not deflect the sand far enough out, sand may continue to flow along the shore, forming a spit around the end of the jetty. A more expensive but effective method to keep a bay <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a> open is to dredge the sand from the growing spit, put it on barges, and deliver it back to the drift downstream of the harbor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a>. An even more expensive but more effective option is to install large pumps and pipes to draw in the sand upstream of the harbor, pump it through pipes, and discharge it back into the drift downstream of the harbor <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a>. Because natural processes work continuously, human efforts to mitigate inconvenient spits and baymouth bars require ongoing modifications. For example, the community of Santa Barbara, California, tried several methods to keep their harbor open before settling on pumps and piping<span class=\"NormalTextRun BCX0 SCXW116966205\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW116966205\">[<\/span><span class=\"NormalTextRun BCX0 SCXW116966205\">2<\/span><span class=\"NormalTextRun BCX0 SCXW116966205\">]<\/span>.<\/p>\n<figure id=\"attachment_3471\" aria-describedby=\"caption-attachment-3471\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/RipCurrent.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-776 size-medium\" title=\"By National Weather Service, Wilmington, NC (NOAA) [Public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-300x300.gif\" alt=\"Some water is rushing outwards while most water rushes in toward the shore.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-300x300.gif 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-150x150.gif 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-65x65.gif 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-225x225.gif 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/RipCurrent-350x350.gif 350w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3471\" class=\"wp-caption-text\">Animation of rip currents.<\/figcaption><\/figure>\n<p>Rip currents are another coastal phenomenon related to longshore currents. <strong>Rip currents<\/strong> occur in the nearshore seafloor when wave trains come <em>straight <\/em>onto the shoreline<strong>.<\/strong> In areas where wave trains push water directly toward the beach face or where the shape of the nearshore seafloor refracts waves toward a specific point on the beach, the water piles up on shore. But this water must find an outlet back to the sea. The outlet is relatively narrow, and rip currents carry the water directly away from the beach. Swimmers caught in rip currents are carried out to sea. Swimming back to shore directly against the strong current is fruitless. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1783\">solution<\/a> for good swimmers is to ride out the current to where it dissipates, swim around it, and return to the beach. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1783\">solution<\/a> for average swimmers is to swim parallel to the beach until out of the current, then return to the beach. Where rip currents are known to exist, warning signs are often posted. The best <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1783\">solution<\/a> is to understand the nature of rip currents, have a plan before entering the water, or watch the signs and avoid them all together.<\/p>\n<p>Like rip currents, undertow is a current that moves away from the shore. However, unlike rip currents, undertow occurs underneath the approaching waves and is strongest in the surf zone where waves are high and water is shallow. Undertow is another return flow for water transported onshore by waves.<\/p>\n<h3><b>12.2.3 Emergent and Submergent Coasts<\/b><\/h3>\n<figure id=\"attachment_3472\" aria-describedby=\"caption-attachment-3472\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-777 size-medium\" title=\"Diliff\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-300x106.jpg\" alt=\"The arch is a rock in the water with a hole in the middle which allows water to pass through.\" width=\"300\" height=\"106\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-300x106.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-1024x362.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-768x272.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-1536x544.jpg 1536w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-65x23.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-225x80.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08-350x124.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Island_Archway_Great_Ocean_Rd_Victoria_Australia_-_Nov_08.jpg 1599w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3472\" class=\"wp-caption-text\">Island Arch, a sea arch in Victoria, Australia.<\/figcaption><\/figure>\n<p><strong>Emergent<\/strong> coasts occur where sea levels fall relative to land level. <strong>Submergent<\/strong> coasts occur where sea levels rise relative to land level. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1654\">Tectonic<\/a> shifts and sea level changes cause the long-term rise and fall of sea level relative to land. Some features associated with emergent coasts include high cliffs, headlands, exposed <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1023\">bedrock<\/a>, steep slopes, rocky shores, arches, stacks, tombolos, wave-cut <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1260\">platforms<\/a>, and wave notches.<\/p>\n<figure id=\"attachment_3473\" aria-describedby=\"caption-attachment-3473\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Angel_Road_Shodo_Island_Japan01s3.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-778 size-medium\" title=\"By 663highland\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-300x200.jpg\" alt=\"The rock in the ocean is connected by the sandy tombolo.\" width=\"300\" height=\"200\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-300x200.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-65x43.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-225x150.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3-350x234.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Angel_Road_Shodo_Island_Japan01s3.jpg 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3473\" class=\"wp-caption-text\">This tombolo, called \u00ab\u00a0Angel Road,\u00a0\u00bb connects the stack of Shodo Island, Japan.<\/figcaption><\/figure>\n<p>In emergent coasts, wave energy, wind, and gravity erode the coastline. The erosional features are elevated relative to the wave zone. Sea cliffs are persistent features as waves cut away at their base and higher rocks calve off by mass wasting. Refracted waves that attack <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1023\">bedrock<\/a> at the base of headlands may erode or carve out a sea arch, which can extend below sea level in a sea cave. When a sea arch collapses, it leaves one or more rock columns called stacks.<\/p>\n<figure id=\"attachment_3474\" aria-describedby=\"caption-attachment-3474\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/WaveCutPlatformsAntelopeIslandUT.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-779 size-medium\" title=\"By Wilson44691 [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-300x104.jpg\" alt=\"Wave notches carved by Lake Bonneville, Antelope Island, Utah.\" width=\"300\" height=\"104\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-300x104.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-1024x354.jpg 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-768x265.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-65x22.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-225x78.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT-350x121.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/WaveCutPlatformsAntelopeIslandUT.jpg 1500w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3474\" class=\"wp-caption-text\">Wave notches carved by Lake Bonneville, Antelope Island, Utah.<\/figcaption><\/figure>\n<p>A stack or near shore island creates a quiet water zone behind it.\u00a0 Sand moving in the longshore drift accumulates in this quiet zone forming a <strong>tombolo<\/strong>: a sand strip that connects the island or stack to the shoreline. Where sand supply is low, wave energy may erode a wave-cut <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1260\">platform<\/a> across the surf zone, exposed as bare rock with tidal pools at low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>. This bench-like terrace extends to the cliff\u2019s base. When wave energy cuts into the base of a sea cliff, it creates a wave notch.<\/p>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_3475\" aria-describedby=\"caption-attachment-3475\" style=\"width: 354px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Chesapeakelandsat.jpeg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-3475\" title=\"By Landsat\/NASA [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Chesapeakelandsat.jpeg\" alt=\"The area is a filled-in river valleys.\" width=\"354\" height=\"266\" \/><\/a><figcaption id=\"caption-attachment-3475\" class=\"wp-caption-text\">Landsat image of Chesapeake Bay, eastern United States. Note the barrier islands parallel to the coastline.<\/figcaption><\/figure>\n<p><strong>Submergent <\/strong>coasts occur where sea levels rise relative to land. This may be due to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1654\">tectonic<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_511\">subsidence<\/a>\u2014when the Earth\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1658\">crust<\/a> sinks\u2014or when sea levels rise due to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1516\">glacier<\/a> melt. Features associated with submergent coasts include flooded river mouths, fjords, barrier islands, lagoons, estuaries, bays, tidal flats, and tidal currents. In submergent coastlines, river mouths are flooded by the rising water, for example Chesapeake Bay. <strong>Fjords<\/strong> are glacial valleys flooded by post-<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_747\">ice age<\/a> sea level rise (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/14-glaciers\/\">Chapter 14<\/a>). Barrier islands are elongated bodies of sand that formed from old beach sands that used to parallel the shoreline. Often, lagoons lie behind barrier islands <span class=\"FindHit BCX0 SCXW30978655\">[<\/span><span class=\"NormalTextRun BCX0 SCXW30978655\">3<\/span><span class=\"NormalTextRun BCX0 SCXW30978655\">]<\/span>. Barrier island formation is controversial: some scientists believe that they formed when <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1519\">ice sheets<\/a> melted after the last <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_747\">ice age<\/a>, raising sea levels. Another <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1730\">hypothesis<\/a> is that barrier islands formed from spits and bars accumulating far offshore.<\/p>\n<figure id=\"attachment_3476\" aria-describedby=\"caption-attachment-3476\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tidal_flat_general_sketch-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-781 size-medium\" title=\"By Foxbat deinos\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-300x225.png\" alt=\"The tidal flat it a network of channels.\" width=\"300\" height=\"225\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-300x225.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-768x576.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-65x49.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-225x169.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1-350x263.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tidal_flat_general_sketch-1.png 960w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3476\" class=\"wp-caption-text\">General diagram of a tidal flat and associated features.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><strong>Tidal flats<\/strong>\u2014or mudflats<em>,<\/em> form where tides alternately flood and expose low areas along the coast. Tidal currents create combinations of symmetrical and asymmetrical ripple marks on mudflats, and drying mud creates mud cracks. In the central Wasatch Mountains of Utah, ancient tidal flat deposits are exposed in the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1270\">Precambrian<\/a> strata of the Big Cottonwood Formation. These ancient deposits provide an example of applying Hutton\u2019s <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1736\">principle of uniformitarianism<\/a> (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/1-understanding-science\/\">Chapter 1<\/a>). Sedimentary structures common on modern tidal flats indicate that these ancient deposits were formed in a similar environment: there were shorelines, tides, and shoreline processes acting at that time, yet the ancient age indicates that there were no land plants to hold products of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_251\">mechanical weathering<\/a> in place (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>), so <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1755\">erosion<\/a> rates would have been different.<\/p>\n<p>Geologically, tidal flats are broken into three different sections: barren zones, marshes, and salt pans. These zones may be present or absent in each individual tidal flat. Barren zones are areas with strong flowing water, coarser <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1756\">sediment<\/a>, with ripple marks and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1509\">cross bedding<\/a> common. Marshes are vegetated with sand and mud. Salt pans or flats, less often submerged than the other zones, are the finest-grained parts of tidal flats, with silty <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1756\">sediment<\/a> and mud cracks (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>)<span class=\"NormalTextRun BCX0 SCXW87010536\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW87010536\">[<\/span><span class=\"NormalTextRun BCX0 SCXW87010536\">4<\/span><span class=\"NormalTextRun BCX0 SCXW87010536\">]<\/span>.<\/p>\n<figure id=\"attachment_3116\" aria-describedby=\"caption-attachment-3116\" style=\"width: 300px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/LaggonKara_bogaz_gol.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-417 size-medium\" title=\"Source: Public domain, by NASA\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-300x300.jpg\" alt=\"The lagoon is just inside the coastline.\" width=\"300\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-300x300.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-150x150.jpg 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-65x65.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-225x225.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol-350x350.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/LaggonKara_bogaz_gol.jpg 639w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3116\" class=\"wp-caption-text\">Kara-Bogaz Gol lagoon, Turkmenistan.<\/figcaption><\/figure>\n<p><strong>Lagoons<\/strong> are locations where spits, barrier islands<em>,<\/em> or other features partially cut off a body of water from the ocean. <strong>Estuaries<\/strong> are a vegetated type of lagoon where fresh water flows into the area making the water brackish\u2014a salinity between salt and fresh water. However, terms like lagoon, estuary, and even bay are often loosely used in place of one another<span class=\"NormalTextRun BCX0 SCXW266504202\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW266504202\">[<\/span><span class=\"NormalTextRun BCX0 SCXW266504202\">5<\/span><span class=\"NormalTextRun BCX0 SCXW266504202\">]<\/span>. Lagoons and estuaries are certainly transitional between land and water environments where littoral, shallow shorelines; lacustrine, lakes or lagoons; and fluvial, rivers or currents can overlap. For more information on lagoons and estuaries, see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a>.<\/p>\n<h3><span style=\"font-weight: 400\">12.2.4 Human impact on coastal beaches<\/span><\/h3>\n<figure id=\"attachment_3477\" aria-describedby=\"caption-attachment-3477\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Groin_effect.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-782 size-medium\" title=\"By Archer0630\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-300x240.jpg\" alt=\"The sediment piled on one side and removed from the other.\" width=\"300\" height=\"240\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-300x240.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-65x52.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-225x180.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect-350x280.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Groin_effect.jpg 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3477\" class=\"wp-caption-text\">Groins gathering sediment from longshore drift.<\/figcaption><\/figure>\n<p>Humans impact coastal beaches when they build homes, condominiums, hotels, businesses, and harbors\u2014and then again when they try to manage the natural processes of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1755\">erosion<\/a>. Waves, currents, longshore drift, and dams at river mouths deplete sand from expensive beachfront property and expose once calm harbors to high-wave energy. To protect their investment, keep sand on their beach, and maintain calm harbors, cities and landowners find ways to mitigate the damage by building jetties, groins, dams, and breakwaters.<\/p>\n<figure id=\"attachment_3478\" aria-describedby=\"caption-attachment-3478\" style=\"width: 236px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-783 size-medium\" title=\"By Internet Archive Book Images\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-236x300.jpg\" alt=\"Series of groins on a coast in Virginia\" width=\"236\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-236x300.jpg 236w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-806x1024.jpg 806w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-768x975.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-1210x1536.jpg 1210w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-1613x2048.jpg 1613w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-65x83.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-225x286.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096-350x444.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/The_Annual_bulletin_of_the_Beach_Erosion_Board_1958_18396945096.jpg 1786w\" sizes=\"auto, (max-width: 236px) 100vw, 236px\" \/><\/a><figcaption id=\"caption-attachment-3478\" class=\"wp-caption-text\">Groin system on a coast in Virginia<\/figcaption><\/figure>\n<p>Jetties are large manmade piles of boulders or concrete barriers built at river mouths and harbors. A jetty is designed to divert the current or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>, to keep a channel to the ocean open, and to protect a harbor or beach from wave action. Groins are similar but smaller than jetties. Groins are fences of wire, wood or concrete built across the beach perpendicular to the shoreline and downstream of a property. Unlike jetties, groins are used to preserve sand on a beach rather than to divert it. Sand erodes on the downstream side of the groin and collects against the upstream side. Every groin on one property thus creates a need for another one on the property downstream. A series of groins along a beach develops a scalloped appearance along the shoreline.<\/p>\n<p>Inland streams and rivers flow to the ocean carrying sand to the longshore current which distributes it to beaches. When dams are built, they trap sand and keep <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1756\">sediment<\/a> from reaching beaches. To replenish beaches, sand may be hauled in from other areas by trucks or barges and dumped on the depleted beach. Unfortunately, this can disrupt the ecosystem that exists along the shoreline by exposing <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_976\">native<\/a> creatures to foreign ecosystems and microorganisms and by introducing foreign objects to humans. For example, visitors to one replenished east coast beach found munitions and metal shards in the sand, which had been dredged from abandoned military test ranges<span class=\"NormalTextRun BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">[<\/span><span class=\"NormalTextRun BCX0 SCXW229124258\" data-ccp-parastyle=\"annotation text\">6]<\/span>.<\/p>\n<figure id=\"attachment_3479\" aria-describedby=\"caption-attachment-3479\" style=\"width: 222px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-784\" title=\"By Internet Archive Book Images\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-273x300.jpg\" alt=\"A tombolo formed behind the breakwater at Venice, CA\" width=\"222\" height=\"244\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-273x300.jpg 273w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-933x1024.jpg 933w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-768x843.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-65x71.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-225x247.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped-350x384.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_1948_20255015848-cropped.jpg 988w\" sizes=\"auto, (max-width: 222px) 100vw, 222px\" \/><\/a><figcaption id=\"caption-attachment-3479\" class=\"wp-caption-text\">A tombolo formed behind the breakwater at Venice, CA<\/figcaption><\/figure>\n<p>An approach to protect harbors and moorings from high-energy wave action is to build a <strong>breakwater<\/strong>\u2014an offshore structure against which the waves break, leaving calmer waters behind it. Unfortunately, breakwaters keep waves from reaching the beach and stop sand moving with longshore drift. When longshore drift is interrupted, sand is deposited in quieter water, and the shoreline builds out forming a tombolo behind the breakwater. The tombolo eventually fill in behind the breakwater with sand<span class=\"NormalTextRun BCX0 SCXW91600808\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW91600808\">[<\/span><span class=\"NormalTextRun BCX0 SCXW91600808\">7]<\/span>. When the city of Venice, California built a breakwater to create a quiet water harbor, longshore drift created a tombolo behind the breakwater, as seen in the image. The tombolo now acts as a large groin in the beach drift.<\/p>\n<h3><span style=\"font-weight: 400\">12.2.5 Submarine Canyons <\/span><\/h3>\n<figure id=\"attachment_3480\" aria-describedby=\"caption-attachment-3480\" style=\"width: 300px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Canyons_off_LA.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-785 size-medium\" title=\"By United States Geological Survey\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-300x213.jpg\" alt=\"The canyons are carved into the slope.\" width=\"300\" height=\"213\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-300x213.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-65x46.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-225x160.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA-350x248.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Canyons_off_LA.jpg 720w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><figcaption id=\"caption-attachment-3480\" class=\"wp-caption-text\">Submarine canyons off of Los Angeles. A=San Gabriel Canyon, B=Newport Canyon. At point C, the canyon is 815 m wide and 25 m deep.<\/figcaption><\/figure>\n<p><strong>Submarine canyons<\/strong> are narrow, deep underwater canyons located on <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1653\">continental<\/a> shelves. Submarine canyons typically form at the mouths of large landward river systems. They form when rivers cut down into the continental shelf during low sea level and when material continually slumps or flows down from the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a> of a river or a delta. Underwater currents rich in <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1756\">sediment<\/a> and more dense than sea water, can flow down the canyons, even erode and deepen them, then drain onto the ocean floor. Underwater <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_246\">landslides<\/a>, called <strong>turbidity flows<\/strong>, occur when steep delta faces and underwater <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1756\">sediment<\/a> flows are released down the continental slope<span class=\"NormalTextRun BCX0 SCXW177996813\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW177996813\">[<\/span><span class=\"NormalTextRun BCX0 SCXW177996813\">8]<\/span>. Turbidity flows in submarine canyons can continue to erode the canyon, and eventually, fan-shaped deposits develop at the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1776\">mouth<\/a> of the canyon on the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1653\">continental<\/a> rise. See <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/5-weathering-erosion-and-sedimentary-rocks\/\">Chapter 5<\/a> for more information on turbidity flows.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-86\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-86\" class=\"h5p-iframe\" data-content-id=\"86\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"12.2 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4710\" aria-describedby=\"caption-attachment-4710\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.2-Did-I-Get-It-QR-Code-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-786\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.2-Did-I-Get-It-QR-Code-1.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4710\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 12.2 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">12.3\u00a0Currents and Tides<\/span><\/h2>\n<p>Ocean water moves as waves, currents, and tides. Ocean currents are driven by persistent global winds blowing over the water\u2019s surface and by water density. Ocean currents are part of Earth\u2019s heat engine in which solar energy is absorbed by ocean water and distributed by ocean currents. Water has another unique property, high specific heat, that relates to ocean currents. <strong>Specific heat<\/strong> is the amount of heat necessary to raise a unit volume of a substance one degree. For water it takes one calorie per cubic centimeter to raise its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1767\">temperature<\/a> one degree Celsius. This means the oceans, covering 71% of the Earth&rsquo;s surface, soak up solar heat with little <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1767\">temperature<\/a> change and distribute that heat around the Earth by ocean currents.<\/p>\n<figure id=\"attachment_3481\" aria-describedby=\"caption-attachment-3481\" style=\"width: 1000px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Corrientes-oceanicas.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-787 size-full\" title=\"By Dr. Michael Pidwirny\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas.png\" alt=\"Warm currents are red, blue currents are blue.\" width=\"1000\" height=\"522\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas.png 1000w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas-300x157.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas-768x401.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas-65x34.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas-225x117.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Corrientes-oceanicas-350x183.png 350w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/a><figcaption id=\"caption-attachment-3481\" class=\"wp-caption-text\">World ocean currents.<\/figcaption><\/figure>\n<h3><span style=\"font-weight: 400\">12.3.1 Surface Currents<\/span><\/h3>\n<p>The Earth\u2019s rotation and the Coriolis effect exert significant influence on ocean currents (see <a href=\"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/chapter\/13-deserts\/\">Chapter 13<\/a>). In the figure, the black arrows show global surface currents. Notice the large circular currents in the northern and southern hemispheres in the Atlantic, Pacific, and Indian Oceans. These currents are called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1478\">gyres<\/a><\/strong> and are driven by atmospheric circulation\u2014air movement<span class=\"NormalTextRun BCX0 SCXW69864823\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW69864823\">[<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">9]<\/span>. <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1478\">Gyres<\/a> rotate clockwise in the northern hemisphere and counterclockwise in the southern hemisphere because of the Coriolis Effect. Western boundary currents flow from the equator toward the poles carrying warm water. They are key contributors to local <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_757\">climate<\/a>.\u00a0Western boundary currents are narrow and move poleward along the east coasts of adjacent continents. The Gulf Stream and the Kuroshio currents in the northern hemisphere and the Brazil, Mozambique, and Australian currents in the southern hemisphere are western boundary currents. Currents returning cold water toward the equator are broad and diffuse along the western coasts of adjacent land masses. These warm western boundary and cold eastern boundary currents affect <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_757\">climate<\/a> of nearby lands making them warmer or colder than other areas at equivalent latitudes. For example, the warm Gulf Stream makes Northern Europe much milder than similar latitudes in northeastern Canada and Greenland. Another example is the cool Humboldt Current, also called the Peru Current, flowing north along the west coast of South America. Cold currents limit evaporation in the ocean, which is one reason the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1492\">Atacama Desert<\/a> in Chile is cool and arid<span class=\"NormalTextRun BCX0 SCXW69864823\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW69864823\">[<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">10<\/span><span class=\"NormalTextRun BCX0 SCXW69864823\">]<\/span>.<\/p>\n<h3><span style=\"font-weight: 400\">12.3.2 Deep Currents<\/span><\/h3>\n<figure id=\"attachment_3482\" aria-describedby=\"caption-attachment-3482\" style=\"width: 442px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Thermohaline_Circulation.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-788\" title=\"By Robert Simmon, NASA. Minor modifications by Robert A. Rohde also released to the public domain\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-300x188.png\" alt=\"In certain areas, the current sinks or rises.\" width=\"442\" height=\"277\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-300x188.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-1024x642.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-768x482.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-65x41.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-225x141.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation-350x220.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Thermohaline_Circulation.png 1100w\" sizes=\"auto, (max-width: 442px) 100vw, 442px\" \/><\/a><figcaption id=\"caption-attachment-3482\" class=\"wp-caption-text\">Global thermohaline circulation. PSS=practical salinity units.<\/figcaption><\/figure>\n<p>Whether an ocean current moves horizontally or vertically depends on its density. The density of seawater is determined by <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1767\">temperature<\/a> and salinity.<\/p>\n<p>Evaporation and freshwater influx from rivers affect salinity and, therefore, the density of seawater. As the western boundary currents cool at high latitudes and salinity increases due to evaporation and ice formation (recall that ice floats; water is densest just above its freezing point). So the cold, denser water sinks to become the ocean\u2019s deep waters. Deep-water movement is called <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1479\">thermohaline circulation<\/a><\/strong>\u2014<em>thermo <\/em>refers to <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1767\">temperature<\/a>, and <em>haline <\/em>refers to salinity. This circulation connects the world\u2019s deep ocean waters. Movement of the Gulf Stream illustrates the beginning of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1479\">thermohaline circulation<\/a>. Heat in the warm poleward moving Gulf Stream promotes\u00a0 evaporation which takes heat from the water and as heat thus dissipates, the water cools. The resulting water is much colder, saltier, and denser. As the denser water reaches the North Atlantic and Greenland, it begins to sink and becomes a deep-water current. As shown in the illustration above, this worldwide connection between shallow and deep-ocean circulation overturns and mixes the entire world ocean, bringing nutrients to marine life, and is sometimes referred to as the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1479\">global conveyor belt<\/a><\/strong><span class=\"NormalTextRun BCX0 SCXW9267996\">\u00a0<\/span><strong><span class=\"FindHit BCX0 SCXW9267996\">[<\/span><span class=\"NormalTextRun BCX0 SCXW9267996\">11]<\/span><\/strong>.<\/p>\n<h3><span style=\"font-weight: 400\">12.3.3 Tides<\/span><\/h3>\n<p><strong>Tides<\/strong> are the rising and lowering of sea level during the day and are caused by the gravitational effects of the Sun and Moon on the oceans<span class=\"NormalTextRun BCX0 SCXW65683472\">\u00a0<\/span><span class=\"FindHit BCX0 SCXW65683472\">[<\/span><span class=\"NormalTextRun BCX0 SCXW65683472\">12]<\/span>. The Earth rotates daily within the Moon and Sun\u2019s gravity fields. Although the Sun is much larger and its gravitational pull is more powerful, the Moon is closer to Earth; hence, the Moon\u2019s gravitational influence on tides is dominant. The magnitude of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> at a given location and the difference between high and low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>\u2014the tidal range, depends primarily on the configuration of the Moon and Sun with respect to the Earth orbit and rotation. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1481\">Spring tide<\/a><\/strong> occurs when the Sun, Moon, and Earth line up with each other at the full or new Moon, and the tidal range is at a maximum. <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1482\">Neap tide<\/a><\/strong> occurs approximately two weeks later when the Moon and Sun are at right angles with the Earth, and the tidal range is lowest.<\/p>\n<p><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tide_schematic.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright wp-image-789 size-medium\" title=\"By User:KVDP, SVG conversion by Surachit\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-300x168.png\" alt=\"\" width=\"300\" height=\"168\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-300x168.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-1024x573.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-768x430.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-65x36.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-225x126.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_-350x196.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_schematic.svg_.png 1140w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<figure id=\"attachment_3484\" aria-describedby=\"caption-attachment-3484\" style=\"width: 198px\" class=\"wp-caption alignleft\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Tide_type.svg_.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-790 size-medium\" title=\"By Snubcube (Own work)\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-198x300.png\" alt=\"Each tide has a different curve.\" width=\"198\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-198x300.png 198w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-675x1024.png 675w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-768x1166.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-65x99.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-225x342.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_-350x531.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Tide_type.svg_.png 1012w\" sizes=\"auto, (max-width: 198px) 100vw, 198px\" \/><\/a><figcaption id=\"caption-attachment-3484\" class=\"wp-caption-text\">Different tide types<\/figcaption><\/figure>\n<p>The Earth rotates within a tidal envelope, so tides rise and ebb daily. Tides are measured at coastal locations. These measurements and the tidal predictions based on them are published on the <a href=\"https:\/\/tidesandcurrents.noaa.gov\/tide_predictions.html\">NOAA website <\/a><span class=\"FindHit BCX0 SCXW77792513\">[<\/span><span class=\"NormalTextRun BCX0 SCXW77792513\">13].<\/span> Tides rising and falling create tidal patterns at any given shore location. The three types of tidal patterns are <em>diurnal,<\/em> <em>semidiurnal,<\/em> and <em>mixed<strong>.<\/strong><\/em><\/p>\n<figure id=\"attachment_3485\" aria-describedby=\"caption-attachment-3485\" style=\"width: 455px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/Diurnal_tide_types_map.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-791\" title=\"By KVDP (Own work) [Public domain]\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-300x147.jpg\" alt=\"The map shows locations of the different tide types.\" width=\"455\" height=\"224\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-300x147.jpg 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-768x377.jpg 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-65x32.jpg 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-225x111.jpg 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map-350x172.jpg 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Diurnal_tide_types_map.jpg 855w\" sizes=\"auto, (max-width: 455px) 100vw, 455px\" \/><\/a><figcaption id=\"caption-attachment-3485\" class=\"wp-caption-text\">Global tide types<\/figcaption><\/figure>\n<p><strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1483\">Diurnal tides<\/a><\/strong> go through one complete cycle each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1484\">tidal day<\/a>. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1484\">tidal day<\/a><\/strong> is the amount of time for the Moon to align with a point on the Earth as the Earth rotates, which is slightly longer than 24 hours. <strong>Semidiurnal<\/strong> tides go through two complete cycles in each <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1484\">tidal day<\/a>\u2014approximately 12 hours and 50 minutes, with the tidal range typically varying in each cycle. <strong>Mixed<\/strong> tides are a combination of diurnal and semidiurnal patterns and show two tidal cycles per <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1484\">tidal day<\/a>, but the relative amplitudes of each cycle and their highs and lows vary during the tidal month. For example, there is a high, high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> and a high, low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>. The next day, there is a low, high <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> and a low, low <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>. Forecasting the tidal pattern and the times tidal phases arrive at a given shore location<\/p>\n<figure id=\"attachment_3486\" aria-describedby=\"caption-attachment-3486\" style=\"width: 281px\" class=\"wp-caption alignright\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2021\/12\/12.3_Lunar_Day_Tide.gif\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-792\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3_Lunar_Day_Tide-281x300.gif\" alt=\"GIF animation showing Earth rotating and tides fluctuating as a result of lunar gravitational forces.\" width=\"281\" height=\"300\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3_Lunar_Day_Tide-281x300.gif 281w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3_Lunar_Day_Tide-65x69.gif 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3_Lunar_Day_Tide-225x240.gif 225w\" sizes=\"auto, (max-width: 281px) 100vw, 281px\" \/><\/a><figcaption id=\"caption-attachment-3486\" class=\"wp-caption-text\">A tidal day lasts slightly longer than 24 hours. Source:<\/figcaption><\/figure>\n<p>is complicated and can be done for only a few days at a time. Tidal phases are determined by <em>bathymetry:<\/em> the depth of ocean basins and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1653\">continental<\/a> obstacles that are in the way of the tidal envelope within which the Earth rotates. Local tidal experts make 48-hour tidal forecasts using tidal charts based on daily observations, as can be seen in the chart of different <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> types. A typical tidal range is approximately 1 m (3 ft). Extreme tidal ranges occur where the tidal wave enters a narrow restrictive zone that funnels the tidal energy. An example is the English Channel between Great Britain and the European <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1653\">continent<\/a> where the tidal range is 7 to 9.75 m (23 to 32 ft). The Earth\u2019s highest tidal ranges occur at the Bay of Fundy, the funnel-like bay between Nova Scotia and New Brunswick, Canada, where the average range is nearly 12 m (40 ft) and the extreme range is around 18 m (60 ft). At extreme tidal range locations, a person who ventures out onto the seafloor exposed during ebb <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a> may not be able to outrun the advancing water during flood <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1480\">tide<\/a>. <a href=\"https:\/\/www.co-ops.nos.noaa.gov\/faq2.html#26\">NOAA<\/a> has additional information on tides.<\/p>\n<h3>Take this quiz to check your comprehension of this section.<\/h3>\n<div id=\"h5p-87\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-87\" class=\"h5p-iframe\" data-content-id=\"87\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"12.3 Did I Get It?\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4711\" aria-describedby=\"caption-attachment-4711\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/12.3-Did-I-Get-It-QR-Code-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-793\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/12.3-Did-I-Get-It-QR-Code-1.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4711\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the quiz for section 12.3 via this QR Code.<\/figcaption><\/figure>\n<h2>Summary<\/h2>\n<p>Shoreline processes are complex, but important for understanding coastal processes. Waves, currents, and tides are the main agents that shape shorelines. Most coastal landforms can be attributed to moving sand via longshore drift, and long-term rising or falling sea levels.<\/p>\n<p>The shoreline is the interface between water and land and is divided into five zones. Processes at the shoreline are called littoral processes. Waves approach the beach at an angle, which cause the waves to bend towards the beach. This bending action is called wave refraction and is responsible for creating the longshore current and longshore drift\u2014the process that moves sand along the coasts. When the longshore current deposits sand along the coast into quieter waters, the sand can accumulate, creating a spit or barrier called a baymouth bar, which often blocks bays and harbors. Inconvenienced humans create methods to keep their harbors open and preserve sand on their beaches by creating jetties and groins, which negatively affect natural beach processes.<\/p>\n<p>Emergent coasts are created by sea levels falling, while submergent coasts are caused by sea levels rising. Oceans absorb solar energy, which is distributed by currents throughout the world. Circular surface currents, called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1478\">gyres<\/a>, rotate clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. Thermohaline deep circulation connects the world\u2019s deep ocean waters: when shallow poleward moving warm water evaporates, the colder, saltier, and denser water sinks and becomes deep-water currents. The connection between shallow and deep-ocean circulation is called the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_795_1479\">global conveyor belt<\/a>.<\/p>\n<p>Tides are the rising and lowering of sea level during the day and are caused by the gravitational effects of the Sun and Moon on the oceans. There are three types of tidal patterns: diurnal, semidiurnal, and mixed. Typical tidal ranges are approximately 1 m (3 ft). Extreme tidal ranges are around 18 m (60 ft).<\/p>\n<h3>Take this quiz to check your comprehension of this Chapter.<\/h3>\n<div id=\"h5p-88\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-88\" class=\"h5p-iframe\" data-content-id=\"88\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Chapter 12 Review\"><\/iframe><\/div>\n<\/div>\n<figure id=\"attachment_4708\" aria-describedby=\"caption-attachment-4708\" style=\"width: 150px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/slcc.pressbooks.pub\/app\/uploads\/sites\/35\/2022\/02\/Ch.12-Review-QR-Code-1.png\"><img loading=\"lazy\" decoding=\"async\" class=\"size-thumbnail wp-image-794\" src=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-150x150.png\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-150x150.png 150w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-300x300.png 300w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-1024x1024.png 1024w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-768x768.png 768w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-65x65.png 65w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-225x225.png 225w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1-350x350.png 350w, https:\/\/integrations.pressbooks.network\/app\/uploads\/sites\/516\/2022\/05\/Ch.12-Review-QR-Code-1.png 1147w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a><figcaption id=\"caption-attachment-4708\" class=\"wp-caption-text\">If you are using the printed version of this OER, access the review quiz for Chapter 12 via this QR Code.<\/figcaption><\/figure>\n<h2><span style=\"font-weight: 400\">References<\/span><\/h2>\n<ol>\n<li><span style=\"color: #000000\">Colling, Angela. 2001. <em>Ocean Circulation<\/em>. Edited by Open University Course Team. Butterworth-Heinemann.<\/span><\/li>\n<li><span style=\"color: #000000\">Davis, Richard A., Jr., and Duncan M. Fitzgerald. 2009. <em>Beaches and Coasts<\/em>. John Wiley &amp; Sons.<\/span><\/li>\n<li><span style=\"color: #000000\">Davis, Richard Albert. 1997. <em>The Evolving Coast<\/em>. Scientific American Library New York.<\/span><\/li>\n<li><span style=\"color: #000000\">Greene, Paul, George Follett, and Clint Henker. 2009. \u201cMunitions and Dredging Experience on the United States Coast.\u201d <em>Marine Technology Society Journal<\/em> 43 (4): 127\u201331.<\/span><\/li>\n<li><span style=\"color: #000000\">Jackson, Nancy L., Mitchell D. Harley, Clara Armaroli, and Karl F. Nordstrom. 2015. \u201cBeach Morphologies Induced by Breakwaters with Different Orientations.\u201d <em>Geomorphology <\/em>\u00a0239 (June). Elsevier: 48\u201357.<\/span><\/li>\n<li><span style=\"color: #000000\">\u201cLittoral Bypassing and Beach Restoration in the Vicinity of Port Hueneme, California.\u201d n.d. In <em>Coastal Engineering 1966<\/em>.<\/span><\/li>\n<li><span style=\"color: #000000\">Munk, Walter H. 1950. \u201cON THE WIND-DRIVEN OCEAN CIRCULATION.\u201d <em>Journal of Meteorology<\/em> 7 (2): 80\u201393.<\/span><\/li>\n<li><span style=\"color: #000000\">Normark, William R., and Paul R. Carlson. 2003. \u201cGiant Submarine Canyons: Is Size Any Clue to Their Importance in the Rock Record?\u201d <em>Geological Society of America Special Papers<\/em> 370 (January): 175\u201390.<\/span><\/li>\n<li><span style=\"color: #000000\">Reineck, H-E, and Indra Bir Singh. 2012. <em>Depositional Sedimentary Environments: With Reference to Terrigenous Clastics<\/em>. Springer Science &amp; Business Media.<\/span><\/li>\n<li><span style=\"color: #000000\">Rich, John Lyon. 1951. \u201cTHREE CRITICAL ENVIRONMENTS OF DEPOSITION, AND CRITERIA FOR RECOGNITION OF ROCKS DEPOSITED IN EACH OF THEM.\u201d <em>Geological Society of America Bulletin<\/em> 62 (1). gsabulletin.gsapubs.org: 1\u201320.<\/span><\/li>\n<li><span style=\"color: #000000\">Runyan, Kiki, and Gary Griggs. 2005. \u201cImplications of Harbor Dredging for the Santa Barbara Littoral Cell.\u201d In <em>California and the World Ocean \u201902<\/em>, 121\u201335. Reston, VA: American Society of Civil Engineers.<\/span><\/li>\n<li><span style=\"color: #000000\">Schwiderski, Ernst W. 1980. \u201cOn Charting Global Ocean Tides.\u201d <em>Reviews of Geophysics <\/em>\u00a018 (1): 243\u201368.<\/span><\/li>\n<li><span style=\"color: #000000\">Stewart, Robert H. 2008. <em>Introduction to Physical Oceanography<\/em>. Texas A &amp; M University Texas.<\/span><\/li>\n<li><span style=\"color: #000000\">Stommel, Henry, and A. B. Arons. 2017. \u201cOn the Abyssal Circulation of the World ocean\u2014I. Stationary Planetary Flow Patterns on a Sphere &#8211; ScienceDirect.\u201d Accessed February 26. <a href=\"http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656<\/a><a style=\"color: #000000\" href=\"https:\/\/urldefense.com\/v3\/__http:\/paperpile.com\/b\/g9x6vx\/VZcZ__;!!NfSqYQ!Vzpmk-s8-k4BNbewuxNNSWTdb45bEiMshN29wwvaDKS0yaTfNqoMN6swSO17i9oKkw$\">.<\/a><\/span><\/li>\n<li><span style=\"color: #000000\">Stommel, Henry, and A. B. Arons. 2017. \u201cOn the Abyssal Circulation of the World ocean\u2014I. Stationary Planetary Flow Patterns on a Sphere &#8211; ScienceDirect.\u201d Accessed February 26. <a href=\"http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sciencedirect.com\/science\/article\/pii\/0146631359900656<\/a>.<\/span><\/li>\n<\/ol>\n<p>&nbsp;<\/p>\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 >PP3       <\/li><li >Deep_water_wave       <\/li><li >Water_wave_diagram       <\/li><li >Wavebase       <\/li><li >Wave_packet_dispersion       <\/li><li >Breaking_wave_types.svg       <\/li><li >Propagation_du_tsunami_en_profondeur_variable       <\/li><li >12.1 Did I Get It QR Code       <\/li><li >Littoral_Zones       <\/li><li >Longshore       <\/li><li >FarewellSpitNZ       <\/li><li >Jetty       <\/li><li >RipCurrent       <\/li><li >Island_Archway,_Great_Ocean_Rd,_Victoria,_Australia_-_Nov_08       <\/li><li >Angel_Road_Shodo_Island_Japan01s3       <\/li><li >WaveCutPlatformsAntelopeIslandUT       <\/li><li >Tidal_flat_general_sketch       <\/li><li >LaggonKara_bogaz_gol       <\/li><li >Groin_effect       <\/li><li >The_Annual_bulletin_of_the_Beach_Erosion_Board_(1958)_(18396945096)       <\/li><li >Venice_CA_breakwater_Bulletin_of_the_Beach_Erosion_Board_(1948)_(20255015848)-cropped       <\/li><li >Canyons_off_LA       <\/li><li >12.2 Did I Get It QR Code       <\/li><li >Corrientes-oceanicas       <\/li><li >Thermohaline_Circulation       <\/li><li >Tide_schematic.svg       <\/li><li >Tide_type.svg       <\/li><li >Diurnal_tide_types_map       <\/li><li >Lunar_Day_Tide       <\/li><li >12.3 Did I Get It QR Code       <\/li><li >Ch.12 Review QR Code       <\/li><\/ul><\/div><div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">d\u00e9finition<\/span><template id=\"term_795_2273\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2273\"><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_795_2169\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2169\"><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_795_2283\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2283\"><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_795_2284\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2284\"><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_795_2038\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2290\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2290\"><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_795_2289\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2289\"><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_795_2212\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1974\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1974\"><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_795_1486\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1486\"><div tabindex=\"-1\"><p>An earthquake that sometimes occurs before the larger mainshock.<\/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_795_2260\"><div class=\"glossary__definition\" role=\"dialog\" 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d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_2264\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2264\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_2265\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2265\"><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_795_2266\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2266\"><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_795_2267\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2267\"><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_795_1946\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1946\"><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_795_756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2269\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2269\"><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_795_2270\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2270\"><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_795_1968\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2271\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2271\"><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_795_1907\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2272\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2272\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_246\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_246\"><div tabindex=\"-1\"><p>By Woudloper (Own work) [Public domain], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AMineralogy_igneous_rocks_EN.svg\">via Wikimedia Commons<\/a><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_228\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_228\"><div tabindex=\"-1\"><p>QR Code generated with QRCode Monkey. All generated QR Codes are 100% free and can be used for whatever you want. This includes all commercial purposes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_985\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_985\"><div tabindex=\"-1\"><p>The thin, outer layer of the Earth which makes up the rocky bottom of the ocean basins. It is made of rocks similar to basalt, and as it cools, even become more dense than the upper mantle below.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_2274\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2274\"><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_795_1480\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1480\"><div tabindex=\"-1\"><p>Faulting that occurs with shear forces, typically on vertical fault plaines as two fault blocks slide past each other.<\/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_795_757\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2275\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2275\"><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_795_2277\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2277\"><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_795_2282\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2282\"><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_795_2303\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2303\"><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_795_1970\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1970\"><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_795_1653\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1967\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1967\"><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_795_2276\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2276\"><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_795_2278\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2278\"><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_795_2279\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2279\"><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_795_2280\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2280\"><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_795_2281\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2281\"><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_795_1947\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2285\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2285\"><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_795_1776\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1776\"><div tabindex=\"-1\"><p>The measure of degrees north or south from the equator, which has a latitude of 0 degrees.&nbsp; The Earth's north and south poles have latitudes of 90 degrees north and south, respectively.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_2286\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2286\"><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_795_2287\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2287\"><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_795_2214\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2214\"><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_795_2288\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2288\"><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_795_1783\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1783\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_1654\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1654\"><div tabindex=\"-1\"><p>Rock with abraded surfaces formed in deserts.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_1023\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1260\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1260\"><div tabindex=\"-1\"><p>Former swamp-derived (plant) material that is part of the rock record.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_2188\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2188\"><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_795_2291\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2291\"><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_795_2292\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2292\"><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_795_2240\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2240\"><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_795_2294\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2294\"><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_795_511\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_511\"><div tabindex=\"-1\"><p>\u00a9 Hans Hillewaert&nbsp;\/&nbsp;, <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AQuinqueloculina_seminula.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_795_1658\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1658\"><div tabindex=\"-1\"><p>Dangerous flooding that occurs in arid regions.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_1516\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1516\"><div tabindex=\"-1\"><p>Component of the gravitational force which pushes material downslope.<\/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_795_2295\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2295\"><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_795_2296\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2296\"><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_795_1978\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1978\"><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_795_2297\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2297\"><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_795_1975\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1975\"><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_795_1988\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1988\"><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_795_747\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1519\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1730\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1730\"><div tabindex=\"-1\"><p>Potentially extractible and valuable material, but unproven.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_1270\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1935\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1935\"><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_795_1736\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1736\"><div tabindex=\"-1\"><p>Material found around ore which is less valuable and needs to be removed in order to obtain ore.<\/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_795_251\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_251\"><div tabindex=\"-1\"><p>By Michael C. Rygel (Own work) [<a href=\"http:\/\/creativecommons.org\/licenses\/by-sa\/3.0\">CC BY-SA 3.0<\/a>], <a href=\"https:\/\/commons.wikimedia.org\/wiki\/File%3AAndesite2.tif\">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_795_1755\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1509\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_2298\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2298\"><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_795_1983\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1983\"><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_795_1981\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1981\"><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_795_2299\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2299\"><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_795_2420\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2420\"><div tabindex=\"-1\"><\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Fermer la d\u00e9finition<\/span><\/button><\/div><\/template><template id=\"term_795_976\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_976\"><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_795_2301\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2301\"><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_795_2302\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2302\"><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_795_1969\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1969\"><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_795_1979\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1963\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1963\"><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_795_1767\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1478\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1492\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_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_795_1479\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1479\"><div tabindex=\"-1\"><p>Term for faulting that occurs in subduction.<\/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_795_1961\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1961\"><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_795_2176\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_2176\"><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_795_1481\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1481\"><div tabindex=\"-1\"><p>Movement in a transform or strike-slip setting which it toward the right across the fault.&nbsp;As viewed across the fault, objects will move to the right.<\/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_795_1482\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1482\"><div tabindex=\"-1\"><p>A small area along a strike-slip or transform fault with branching structures of transpression\/transtension, causing local hills or valleys.<\/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_795_1483\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1483\"><div tabindex=\"-1\"><p>A theory of building energy that is released during 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_795_1484\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_795_1484\"><div tabindex=\"-1\"><p>Initiation point of an earthquake or fault movement.<\/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":12,"template":"","meta":{"pb_show_title":"","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[49],"contributor":[],"license":[],"class_list":["post-795","chapter","type-chapter","status-publish","hentry","chapter-type-numberless"],"part":19,"_links":{"self":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/795","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\/795\/revisions"}],"predecessor-version":[{"id":1801,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapters\/795\/revisions\/1801"}],"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\/795\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/media?parent=795"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/pressbooks\/v2\/chapter-type?post=795"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/contributor?post=795"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/integrations.pressbooks.network\/testcloneglossaryterms\/wp-json\/wp\/v2\/license?post=795"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}