{"id":393,"date":"2015-07-10T22:37:37","date_gmt":"2015-07-10T22:37:37","guid":{"rendered":"https:\/\/courses.candelalearning.com\/earthscienceck12\/?post_type=chapter&#038;p=393"},"modified":"2015-07-10T23:00:29","modified_gmt":"2015-07-10T23:00:29","slug":"water-erosion-and-deposition","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/chapter\/water-erosion-and-deposition\/","title":{"raw":"Water Erosion and Deposition","rendered":"Water Erosion and Deposition"},"content":{"raw":"<body>\n    <h2>\n      Lesson Objectives\n    <\/h2>\n    <ul>\n<li>Describe how surface streams produce erosion.\n      <\/li>\n      <li>Describe the types of deposits left behind by streams.\n      <\/li>\n      <li>Describe landforms that are produced as ground water flows.\n      <\/li>\n    <\/ul>\n<h2>\n      Vocabulary\n    <\/h2>\n    <ul>\n<li>alluvial fan\n      <\/li>\n      <li>base level\n      <\/li>\n      <li>bed load\n      <\/li>\n      <li>column\n      <\/li>\n      <li>competence\n      <\/li>\n      <li>delta\n      <\/li>\n      <li>dissolved load\n      <\/li>\n      <li>floodplain\n      <\/li>\n      <li>gradient\n      <\/li>\n      <li>groundwater\n      <\/li>\n      <li>headwaters\n      <\/li>\n      <li>meander\n      <\/li>\n      <li>natural levee\n      <\/li>\n      <li>saltation\n      <\/li>\n      <li>sinkhole\n      <\/li>\n      <li>stalactite\n      <\/li>\n      <li>stalagmite\n      <\/li>\n      <li>suspended load\n      <\/li>\n      <li>travertine\n      <\/li>\n    <\/ul>\n<h2>\n      Introduction\n    <\/h2>\n    <p>\n      Streams \u2013 any running water from a rivulet to a raging river -- complete the hydrologic cycle by returning precipitation that falls on land to the oceans (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDE.\">below<\/a>). Some of this water moves over the surface and some moves through the ground as <strong>groundwater.<\/strong> Flowing water does the work of both erosion and deposition.\n    <\/p>\n    <div class=\"x-ck12-img-thumbnail x-ck12-nofloat\">\n      <!-- @@author=\"Horia Varlan\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/horiavarlan\/5099223501\/\" --><!-- @@license=\"CC BY 2.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223701\/201412291419878482724159_4f674ec1a791a88d20b814554dd49492-201412291419879202559967.jpg\" title=\"\" longdesc=\"As%20streams%20flow%20towards%20the%20ocean%2C%20they%20carry%20weathered%20materials.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDE.\"><\/p>\n      <p>\n        As streams flow towards the ocean, they carry weathered materials.\n      <\/p>\n    <\/div>\n    <h2>\n      Erosion and Deposition by Streams\n    <\/h2>\n    <h3>\n      Erosion by Streams\n    <\/h3>\n    <p>\n      Flowing streams pick up and transport weathered materials by eroding sediments from their banks. Streams also carry ions and ionic compounds that dissolve easily in the water. Sediments are carried as:\n    <\/p>\n    <ul>\n<li>\n        <strong>Dissolved load<\/strong>: Dissolved load is composed of ions in solution. These ions are usually carried in the water all the way to the ocean.\n      <\/li>\n      <li>\n        <strong>Suspended load<\/strong>: Sediments carried as solids as the stream flows are suspended load. The size of particles that can be carried is determined by the stream\u2019s velocity (<strong>Figure<\/strong> <a href=\"#x-ck12-RVMgU2thd2EgUml2ZXI.\">below<\/a>). Faster streams can carry larger particles. Streams that carry larger particles have greater <strong>competence<\/strong>. Streams with a steep <strong>gradient<\/strong> (slope) have a faster velocity and greater competence.\n      <\/li>\n    <\/ul>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Paulo Ordoveza\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/brownpau\/8432363039\/\" --><!-- @@license=\"CC BY 2.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223701\/201412291419878482782302_0ed023022b32cb3c6ee166f0d7a8e3c4-201412291419879203022524.jpg\" title=\"\" longdesc=\"Rivers%20carry%20sand%2C%20silt%20and%20clay%20as%20suspended%20load.%20During%20flood%20stage%2C%20the%20suspended%20load%20greatly%20increases%20as%20stream%20velocity%20increases.%20\" alt=\"\" id=\"x-ck12-RVMgU2thd2EgUml2ZXI.\"><\/p>\n      <p>\n        Rivers carry sand, silt and clay as suspended load. During flood stage, the suspended load greatly increases as stream velocity increases.\n      <\/p>\n    <\/div>\n    <ul>\n<li>\n        <strong>Bed load<\/strong>: Particles that are too large to be carried as suspended load are bumped and pushed along the stream bed as bed load. Bed load sediments do not move continuously. This intermittent movement is called <strong>saltation<\/strong>. Streams with high velocities and steep gradients do a great deal of down cutting into the stream bed, which is primarily accomplished by movement of particles that make up the bed load.\n      <\/li>\n      <li>A video of bedload transport is found here: <a href=\"http:\/\/faculty.gg.uwyo.edu\/heller\/SedMovs\/Sed%20Movie%20files\/bdld.mov\">http:\/\/faculty.gg.uwyo.edu\/heller\/SedMovs\/Sed%20Movie%20files\/bdld.mov<\/a>\n      <\/li>\n    <\/ul>\n<h3>\n      Stages of Streams\n    <\/h3>\n    <p>\n      As a stream flows from higher elevations, like in the mountains, towards lower elevations, like the ocean, the work of the stream changes. At a stream\u2019s <strong>headwaters<\/strong>, often high in the mountains, gradients are steep (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDktMDMtU3RyZWFtLW1lbHR3YXRlci5qcGc.\">below<\/a>). The stream moves fast and does lots of work eroding the stream bed.\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Ryan Schreiber\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/ryanschreiber\/2921183175\/\" --><!-- @@license=\"CC BY 2.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223703\/201412291419878482812288_37c3d2b39b21e3e588e237f0eac254ad-201412291419879203466127.jpg\" title=\"\" longdesc=\"This%20stream%20begins%20as%20snow%20melt%20from%20the%20mountains.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMDktMDMtU3RyZWFtLW1lbHR3YXRlci5qcGc.\"><\/p>\n      <p>\n        This stream begins as snow melt from the mountains.\n      <\/p>\n    <\/div>\n    <p>\n      As a stream moves into lower areas, the gradient is not as steep. Now the stream does more work eroding the edges of its banks. Many streams develop curves in their channels called <strong>meanders<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDQtTWVhbmRlcnM.\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"(a) Benjamin Dobson; (b) SuzanneKn; (c) Courtesy of USDA\/FSA\" --><!-- @@url=\"(a) http:\/\/www.flickr.com\/photos\/systemaabstra\/3498420570\/; (b) http:\/\/commons.wikimedia.org\/wiki\/File:Meander_in_Ashes_Hollow.jpg; (c) http:\/\/commons.wikimedia.org\/wiki\/File:GooseneckMeandersUtahAerial1.jpg\" --><!-- @@license=\"(a) CC BY 2.0; (b)Public Domain; (c) Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223704\/201412291419878482901769_e376d24e3c54dd6930c1da43000c9f25-201412291419879204162704.jpg\" title=\"\" longdesc=\"%28a%29%20At%20a%20meander%2C%20a%20stream%20actively%20erodes%20its%20outer%20banks%20and%20deposits%20material%20along%20the%20inside%20curves.%20This%20causes%20these%20meanders%20to%20migrate%20laterally%20over%20time.%20%28b%29%20This%20stream%20has%20deposited%20larger%20materials%20such%20as%20gravel%20and%20pebbles%20along%20the%20inside%20curve%20of%20a%20meander.%20%28c%29%20This%20image%20is%20a%20topographic%20map.%20The%20San%20Juan%20River%20eroded%20the%20land%20surface%20as%20the%20Colorado%20Plateau%20uplifted.%20The%20river%26%238217%3Bs%20meanders%20were%20preserved%20as%20a%20feature%20called%20incised%20meanders.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDQtTWVhbmRlcnM.\"><\/p>\n      <p>\n        (a) At a meander, a stream actively erodes its outer banks and deposits material along the inside curves. This causes these meanders to migrate laterally over time. (b) This stream has deposited larger materials such as gravel and pebbles along the inside curve of a meander. (c) This image is a topographic map. The San Juan River eroded the land surface as the Colorado Plateau uplifted. The river\u2019s meanders were preserved as a feature called incised meanders.\n      <\/p>\n    <\/div>\n    <p>\n      As the river moves onto flatter ground, the stream erodes the outer edges of its banks to carve a <strong>floodplain<\/strong>, which is a flat level area surrounding the stream channel (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtVmlzdHVsYS1yaXZlci5qcGc.\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of Johnson Space Center\/NASA's Earth Observatory\" --><!-- @@url=\"http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=44102\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223706\/201412291419878482916960_2baf33078b3851c09e216a624dc47e8e-201412291419879204798039.jpg\" title=\"\" longdesc=\"The%20Vistula%20River%20in%20Poland%20flows%20onto%20its%20floodplain.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtVmlzdHVsYS1yaXZlci5qcGc.\"><\/p>\n      <p>\n        The Vistula River in Poland flows onto its floodplain.\n      <\/p>\n    <\/div>\n    <p>\n      <strong>Base level<\/strong> is where a stream meets a large body of standing water, usually the ocean, but sometimes a lake or pond. Streams work to down cut in their stream beds until they reach base level. The higher the elevation, the farther the stream is from where it will reach base level and the more cutting it has to do.\n    <\/p>\n    <h3>\n      Stream Deposition\n    <\/h3>\n    <p>\n      As a stream gets closer to base level, its gradient lowers and it deposits more material than it erodes. On flatter ground, streams deposit material on the inside of meanders. Placer mineral deposits, described in the Earth's Minerals chapter, are often deposited there. A stream\u2019s floodplain is much broader and shallower than the stream\u2019s channel. When a stream flows onto its floodplain, its velocity slows and it deposits much of its load. These sediments are rich in nutrients and make excellent farmland (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtTWlzc2lzc2lwcGktZmxvb2RwbGFpbi5qcGc.\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of Jesse Allen\/NASA's Earth Observatory\" --><!-- @@url=\"http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=5422\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223707\/201412291419878482962173_b464987451ed380c8aceacb35ff91a32-201412291419879205250801.jpg\" title=\"\" longdesc=\"The%20Mississippi%20floodplain%20is%20heavily%20farmed.%20Flooding%20can%20wipe%20out%20farms%20and%20towns%2C%20but%20the%20stream%20also%20deposits%20nutrient-rich%20sediments%20that%20enrich%20the%20floodplain.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtTWlzc2lzc2lwcGktZmxvb2RwbGFpbi5qcGc.\"><\/p>\n      <p>\n        The Mississippi floodplain is heavily farmed. Flooding can wipe out farms and towns, but the stream also deposits nutrient-rich sediments that enrich the floodplain.\n      <\/p>\n    <\/div>\n    <p>\n      A stream at flood stage carries lots of sediments. When its gradient decreases, the stream overflows its banks and broadens its channel. The decrease in gradient causes the stream to deposit its sediments, the largest first. These large sediments build a higher area around the edges of the stream channel, creating <strong>natural levees<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDVh\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"CK-12 Foundation\" --><!-- @@url=\"CK-12 Foundation\" --><!-- @@license=\"CC BY-NC 3.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223708\/201412291419878482980212_a561924b4ceaf08c7b899571e343b28a-201412291419879206088642.jpg\" title=\"\" longdesc=\"After%20many%20floods%2C%20a%20stream%20builds%20natural%20levees%20along%20its%20banks.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDVh\"><\/p>\n      <p>\n        After many floods, a stream builds natural levees along its banks.\n      <\/p>\n    <\/div>\n    <p>\n      When a river enters standing water, its velocity slows to a stop. The stream moves back and forth across the region and drops its sediments in a wide triangular-shaped deposit called a <strong>delta<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtRGVsdGFz\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"(a) Courtesy of NASA\/GSFC\/JPL, MISR Team; (b) Courtesy of Robert Simmon\/NASA's Earth Observatory\" --><!-- @@url=\"(a) http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=1234; (b) http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=42439\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223710\/201412291419878483011765_f50c5fec24629d6a4861f93b7add3382-201412291419879206924548.jpg\" title=\"\" longdesc=\"%28a%29%20The%20Nile%20River%20delta%20has%20a%20classic%20triangular%20shape%2C%20like%20the%20capital%20Greek%20letter%20delta.%20%28b%29%20Sediment%20in%20the%20Yellow%20River%20delta.%20The%20main%20stream%20channel%20splits%20into%20many%20smaller%20distributaries.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtRGVsdGFz\"><\/p>\n      <p>\n        (a) The Nile River delta has a classic triangular shape, like the capital Greek letter delta. (b) Sediment in the Yellow River delta. The main stream channel splits into many smaller distributaries.\n      <\/p>\n    <\/div>\n    <p>\n      If a stream falls down a steep slope onto a broad flat valley, an <strong>alluvial fan<\/strong> develops (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDg.\">below<\/a>). Alluvial fans generally form in arid regions.\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of NASA image created by Jesse Allen, using data from NASA\/GSFC\/METI\/ERSDAC\/JAROS, and the U.S.\/Japan ASTER Science Team\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Alluvial_fan_in_Iran.jpg\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223711\/201412291419878483042055_4bece62103e4791f7e525fe9960b22c4-201412291419879207638346.jpg\" title=\"\" longdesc=\"An%20alluvial%20fan%20in%20Iran.%20The%20mountains%20are%20in%20the%20lower%20right%20corner%20of%20the%20photograph.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDg.\"><\/p>\n      <p>\n        An alluvial fan in Iran. The mountains are in the lower right corner of the photograph.\n      <\/p>\n    <\/div>\n    <h2>\n      Ground Water Erosion and Deposition\n    <\/h2>\n    <p>\n      Rainwater absorbs carbon dioxide (CO<sub>2<\/sub>) as it falls. The CO<sub>2<\/sub> combines with water to form carbonic acid. The slightly acidic water sinks into the ground and moves through pore spaces in soil and cracks and fractures in rock. The flow of water underground is <strong>ground water.<\/strong>\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"J.B. Martin\" --><!-- @@url=\"CK-12 Foundation\" --><!-- @@license=\"CC BY-NC 3.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223713\/201412291419878483142066_03ae5d7d413fd22431874218b03ec779-201412291419879208235854.jpg\" title=\"\" longdesc=\"When%20water%20sinks%20into%20the%20ground%2C%20it%20becomes%20ground%20water.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMQ..\"><\/p>\n      <p>\n        When water sinks into the ground, it becomes ground water.\n      <\/p>\n    <\/div>\n    <p>\n      Ground water is a strong erosional force, as it works to dissolve away solid rock (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMQ..\">above<\/a>). Carbonic acid is especially good at dissolving the rock limestone.\n    <\/p>\n    <h3>\n      Cave Formation\n    <\/h3>\n    <p>\n      Working slowly over many years, ground water travels along small cracks. The water dissolves and carries away the solid rock gradually enlarging the cracks. Eventually a cave may form (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMg..\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"User:Thelmadatter\/Wikipedia\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:RiverExitTolantongo.JPG\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223714\/201412291419878483165530_75710761d76ec9626e8c165d19f0429e-201412291419879208670231.jpg\" title=\"\" longdesc=\"Caverns%20many%20football%20fields%20long%20and%20as%20high%20as%20many%20meters%20tall%20form%20where%20ground%20water%20erodes%20away%20rock.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMg..\"><\/p>\n      <p>\n        Caverns many football fields long and as high as many meters tall form where ground water erodes away rock.\n      <\/p>\n    <\/div>\n    <p>\n      Ground water carries the dissolved minerals in solution. The minerals may then be deposited, for example, as <strong>stalagmites<\/strong> or <strong>stalactites<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMTItQ2F2ZS1mb3JtYXRpb24.\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"(a) Dave Pape; (b)  B\u00f6rkur Sigurbj\u00f6rnsson\" --><!-- @@url=\"(a) http:\/\/commons.wikimedia.org\/wiki\/File:Stalactites_-_Treak_Cliff_Cavern.jpg; (b) http:\/\/www.flickr.com\/photos\/borkurdotnet\/2078879358\/\" --><!-- @@license=\"(a) Public Domain; (b) CC BY 2.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223715\/201412291419878483211822_05ee1b404aa683aada01cf76e84d158f-201412291419879209133058.jpg\" title=\"\" longdesc=\"%28a%29%20Stalactites%20form%20as%20calcium%20carbonate%20drips%20from%20the%20ceiling%20of%20a%20cave%2C%20forming%20beautiful%20icicle-like%20formations.%20The%20word%20stalactite%20has%20a%20c%20and%20it%20forms%20from%20the%20ceiling.%20%28b%29%20Stalagmites%20form%20as%20calcium%20carbonate%20drips%20from%20the%20ceiling%20to%20the%20floor%20of%20a%20cave%20and%20then%20grow%20upwards.%20The%20g%20in%20stalagmite%20means%20it%20forms%20on%20the%20ground.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMTItQ2F2ZS1mb3JtYXRpb24.\"><\/p>\n      <p>\n        (a) Stalactites form as calcium carbonate drips from the ceiling of a cave, forming beautiful icicle-like formations. The word stalactite has a c and it forms from the ceiling. (b) Stalagmites form as calcium carbonate drips from the ceiling to the floor of a cave and then grow upwards. The g in stalagmite means it forms on the ground.\n      <\/p>\n    <\/div>\n    <p>\n      If a stalactite and stalagmite join together, they form a <strong>column<\/strong>. One of the wonders of visiting a cave is to witness the beauty of these amazing and strangely captivating structures. Caves also produce a beautiful rock, formed from calcium carbonate, <strong>travertine<\/strong>. Ground water saturated with calcium carbonate precipitates as the mineral calcite or aragonite. Mineral springs that produce travertine can be hot, warm or even cold (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wNQ..\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Paul VanDerWerf\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/pavdw\/10644540916\/\" --><!-- @@license=\"CC BY 2.0\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223717\/201412291419878483321754_c86c2ec3dbee94cf88fc4f2028e8648c-201412291419879209697674.jpg\" title=\"\" longdesc=\"Travertine%20is%20a%20beautiful%20form%20of%20limestone.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wNQ..\"><\/p>\n      <p>\n        Travertine is a beautiful form of limestone.\n      <\/p>\n    <\/div>\n    <p>\n      You can explore a fantastic cave, Kartchner Caverns, in Arizona, by watching this video: <a href=\"http:\/\/video.nationalgeographic.com\/video\/player\/science\/earth-sci\/exploring-kartchner-sci.html\">http:\/\/video.nationalgeographic.com\/video\/player\/science\/earth-sci\/exploring-kartchner-sci.html<\/a>\n    <\/p>\n    <p>\n      If the roof of a cave collapses, a <strong>sinkhole<\/strong> could form. Some sinkholes are large enough to swallow up a home or several homes in a neighborhood (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMw..\">below<\/a>).\n    <\/p>\n    <div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Mason Berry\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:WOAHdubs.jpg\" --><!-- @@license=\"Public Domain\" -->\n      <p>\n        <img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223718\/201412291419878483351294_1941ef423958d4046f9684ebd76dd6dc-201412291419879210717821.jpg\" title=\"\" longdesc=\"This%20sinkhole%20formed%20in%20Florida.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMw..\"><\/p>\n      <p>\n        This sinkhole formed in Florida.\n      <\/p>\n    <\/div>\n    <h2>\n      Lesson Summary\n    <\/h2>\n    <ul>\n<li>Streams erode the land as they move from higher elevations to the sea.\n      <\/li>\n      <li>Eroded materials can be carried in a river as dissolved load, suspended load, or bed load.\n      <\/li>\n      <li>A river erodes deeply when it is far from its base level, the place where it enters standing water.\n      <\/li>\n      <li>Streams form bends, called meanders. Broad, flat areas are known as floodplains.\n      <\/li>\n      <li>A delta or an alluvial fan might form where the stream drops its sediment load.\n      <\/li>\n      <li>Caves form underground as ground water gradually dissolves away rock.\n      <\/li>\n    <\/ul>\n<h2>\n      Review Questions\n    <\/h2>\n    <ol id=\"x-ck12-MjZhMjU5NDU0NTI3ZjAyOTk0YmZhNGJiYjhkYzJkOWU.-jvd\" class=\"x-ck12-decimal\">\n<li>Define the three kinds of load that make up the particles a stream carries.\n      <\/li>\n      <li>What is a stream\u2019s gradient? What effect does it have on the work of a stream?\n      <\/li>\n      <li>How do streams erode their beds?\n      <\/li>\n      <li>How does a stream produce a wide, flat floodplain?\n      <\/li>\n      <li>What type of gradient would a river have when it is actively eroding its stream bed?\n      <\/li>\n      <li>When would a river form an alluvial fan and when will it form a delta? Describe the characteristics of each type of deposit.\n      <\/li>\n      <li>What are two formations that form inside caves?\n      <\/li>\n      <li>What erosional feature formed by ground water could swallow up your house?\n      <\/li>\n    <\/ol>\n<h2>\n      Points to Consider\n    <\/h2>\n    <ul>\n<li>Would a stream at high elevations erode more than a stream at lower elevations?\n      <\/li>\n      <li>How would Earth\u2019s surface look without streams?\n      <\/li>\n      <li>Would a flash flood along a normally dry river valley be a dangerous event?\n      <\/li>\n      <li>Do you think caves could form in your neighborhood?\n      <\/li>\n    <\/ul>\n<\/body>","rendered":"<h2>\n      Lesson Objectives<br \/>\n    <\/h2>\n<ul>\n<li>Describe how surface streams produce erosion.\n      <\/li>\n<li>Describe the types of deposits left behind by streams.\n      <\/li>\n<li>Describe landforms that are produced as ground water flows.\n      <\/li>\n<\/ul>\n<h2>\n      Vocabulary<br \/>\n    <\/h2>\n<ul>\n<li>alluvial fan\n      <\/li>\n<li>base level\n      <\/li>\n<li>bed load\n      <\/li>\n<li>column\n      <\/li>\n<li>competence\n      <\/li>\n<li>delta\n      <\/li>\n<li>dissolved load\n      <\/li>\n<li>floodplain\n      <\/li>\n<li>gradient\n      <\/li>\n<li>groundwater\n      <\/li>\n<li>headwaters\n      <\/li>\n<li>meander\n      <\/li>\n<li>natural levee\n      <\/li>\n<li>saltation\n      <\/li>\n<li>sinkhole\n      <\/li>\n<li>stalactite\n      <\/li>\n<li>stalagmite\n      <\/li>\n<li>suspended load\n      <\/li>\n<li>travertine\n      <\/li>\n<\/ul>\n<h2>\n      Introduction<br \/>\n    <\/h2>\n<p>\n      Streams \u2013 any running water from a rivulet to a raging river &#8212; complete the hydrologic cycle by returning precipitation that falls on land to the oceans (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDE.\">below<\/a>). Some of this water moves over the surface and some moves through the ground as <strong>groundwater.<\/strong> Flowing water does the work of both erosion and deposition.\n    <\/p>\n<div class=\"x-ck12-img-thumbnail x-ck12-nofloat\">\n      <!-- @@author=\"Horia Varlan\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/horiavarlan\/5099223501\/\" --><!-- @@license=\"CC BY 2.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223701\/201412291419878482724159_4f674ec1a791a88d20b814554dd49492-201412291419879202559967.jpg\" title=\"\" longdesc=\"As%20streams%20flow%20towards%20the%20ocean%2C%20they%20carry%20weathered%20materials.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDE.\" \/><\/p>\n<p>\n        As streams flow towards the ocean, they carry weathered materials.\n      <\/p>\n<\/p><\/div>\n<h2>\n      Erosion and Deposition by Streams<br \/>\n    <\/h2>\n<h3>\n      Erosion by Streams<br \/>\n    <\/h3>\n<p>\n      Flowing streams pick up and transport weathered materials by eroding sediments from their banks. Streams also carry ions and ionic compounds that dissolve easily in the water. Sediments are carried as:\n    <\/p>\n<ul>\n<li>\n        <strong>Dissolved load<\/strong>: Dissolved load is composed of ions in solution. These ions are usually carried in the water all the way to the ocean.\n      <\/li>\n<li>\n        <strong>Suspended load<\/strong>: Sediments carried as solids as the stream flows are suspended load. The size of particles that can be carried is determined by the stream\u2019s velocity (<strong>Figure<\/strong> <a href=\"#x-ck12-RVMgU2thd2EgUml2ZXI.\">below<\/a>). Faster streams can carry larger particles. Streams that carry larger particles have greater <strong>competence<\/strong>. Streams with a steep <strong>gradient<\/strong> (slope) have a faster velocity and greater competence.\n      <\/li>\n<\/ul>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Paulo Ordoveza\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/brownpau\/8432363039\/\" --><!-- @@license=\"CC BY 2.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223701\/201412291419878482782302_0ed023022b32cb3c6ee166f0d7a8e3c4-201412291419879203022524.jpg\" title=\"\" longdesc=\"Rivers%20carry%20sand%2C%20silt%20and%20clay%20as%20suspended%20load.%20During%20flood%20stage%2C%20the%20suspended%20load%20greatly%20increases%20as%20stream%20velocity%20increases.%20\" alt=\"\" id=\"x-ck12-RVMgU2thd2EgUml2ZXI.\" \/><\/p>\n<p>\n        Rivers carry sand, silt and clay as suspended load. During flood stage, the suspended load greatly increases as stream velocity increases.\n      <\/p>\n<\/p><\/div>\n<ul>\n<li>\n        <strong>Bed load<\/strong>: Particles that are too large to be carried as suspended load are bumped and pushed along the stream bed as bed load. Bed load sediments do not move continuously. This intermittent movement is called <strong>saltation<\/strong>. Streams with high velocities and steep gradients do a great deal of down cutting into the stream bed, which is primarily accomplished by movement of particles that make up the bed load.\n      <\/li>\n<li>A video of bedload transport is found here: <a href=\"http:\/\/faculty.gg.uwyo.edu\/heller\/SedMovs\/Sed%20Movie%20files\/bdld.mov\">http:\/\/faculty.gg.uwyo.edu\/heller\/SedMovs\/Sed%20Movie%20files\/bdld.mov<\/a>\n      <\/li>\n<\/ul>\n<h3>\n      Stages of Streams<br \/>\n    <\/h3>\n<p>\n      As a stream flows from higher elevations, like in the mountains, towards lower elevations, like the ocean, the work of the stream changes. At a stream\u2019s <strong>headwaters<\/strong>, often high in the mountains, gradients are steep (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDktMDMtU3RyZWFtLW1lbHR3YXRlci5qcGc.\">below<\/a>). The stream moves fast and does lots of work eroding the stream bed.\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Ryan Schreiber\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/ryanschreiber\/2921183175\/\" --><!-- @@license=\"CC BY 2.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223703\/201412291419878482812288_37c3d2b39b21e3e588e237f0eac254ad-201412291419879203466127.jpg\" title=\"\" longdesc=\"This%20stream%20begins%20as%20snow%20melt%20from%20the%20mountains.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMDktMDMtU3RyZWFtLW1lbHR3YXRlci5qcGc.\" \/><\/p>\n<p>\n        This stream begins as snow melt from the mountains.\n      <\/p>\n<\/p><\/div>\n<p>\n      As a stream moves into lower areas, the gradient is not as steep. Now the stream does more work eroding the edges of its banks. Many streams develop curves in their channels called <strong>meanders<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDQtTWVhbmRlcnM.\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"(a) Benjamin Dobson; (b) SuzanneKn; (c) Courtesy of USDA\/FSA\" --><!-- @@url=\"(a) http:\/\/www.flickr.com\/photos\/systemaabstra\/3498420570\/; (b) http:\/\/commons.wikimedia.org\/wiki\/File:Meander_in_Ashes_Hollow.jpg; (c) http:\/\/commons.wikimedia.org\/wiki\/File:GooseneckMeandersUtahAerial1.jpg\" --><!-- @@license=\"(a) CC BY 2.0; (b)Public Domain; (c) Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223704\/201412291419878482901769_e376d24e3c54dd6930c1da43000c9f25-201412291419879204162704.jpg\" title=\"\" longdesc=\"%28a%29%20At%20a%20meander%2C%20a%20stream%20actively%20erodes%20its%20outer%20banks%20and%20deposits%20material%20along%20the%20inside%20curves.%20This%20causes%20these%20meanders%20to%20migrate%20laterally%20over%20time.%20%28b%29%20This%20stream%20has%20deposited%20larger%20materials%20such%20as%20gravel%20and%20pebbles%20along%20the%20inside%20curve%20of%20a%20meander.%20%28c%29%20This%20image%20is%20a%20topographic%20map.%20The%20San%20Juan%20River%20eroded%20the%20land%20surface%20as%20the%20Colorado%20Plateau%20uplifted.%20The%20river%26%238217%3Bs%20meanders%20were%20preserved%20as%20a%20feature%20called%20incised%20meanders.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDQtTWVhbmRlcnM.\" \/><\/p>\n<p>\n        (a) At a meander, a stream actively erodes its outer banks and deposits material along the inside curves. This causes these meanders to migrate laterally over time. (b) This stream has deposited larger materials such as gravel and pebbles along the inside curve of a meander. (c) This image is a topographic map. The San Juan River eroded the land surface as the Colorado Plateau uplifted. The river\u2019s meanders were preserved as a feature called incised meanders.\n      <\/p>\n<\/p><\/div>\n<p>\n      As the river moves onto flatter ground, the stream erodes the outer edges of its banks to carve a <strong>floodplain<\/strong>, which is a flat level area surrounding the stream channel (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtVmlzdHVsYS1yaXZlci5qcGc.\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of Johnson Space Center\/NASA's Earth Observatory\" --><!-- @@url=\"http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=44102\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223706\/201412291419878482916960_2baf33078b3851c09e216a624dc47e8e-201412291419879204798039.jpg\" title=\"\" longdesc=\"The%20Vistula%20River%20in%20Poland%20flows%20onto%20its%20floodplain.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtVmlzdHVsYS1yaXZlci5qcGc.\" \/><\/p>\n<p>\n        The Vistula River in Poland flows onto its floodplain.\n      <\/p>\n<\/p><\/div>\n<p>\n      <strong>Base level<\/strong> is where a stream meets a large body of standing water, usually the ocean, but sometimes a lake or pond. Streams work to down cut in their stream beds until they reach base level. The higher the elevation, the farther the stream is from where it will reach base level and the more cutting it has to do.\n    <\/p>\n<h3>\n      Stream Deposition<br \/>\n    <\/h3>\n<p>\n      As a stream gets closer to base level, its gradient lowers and it deposits more material than it erodes. On flatter ground, streams deposit material on the inside of meanders. Placer mineral deposits, described in the Earth&#8217;s Minerals chapter, are often deposited there. A stream\u2019s floodplain is much broader and shallower than the stream\u2019s channel. When a stream flows onto its floodplain, its velocity slows and it deposits much of its load. These sediments are rich in nutrients and make excellent farmland (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtTWlzc2lzc2lwcGktZmxvb2RwbGFpbi5qcGc.\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of Jesse Allen\/NASA's Earth Observatory\" --><!-- @@url=\"http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=5422\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223707\/201412291419878482962173_b464987451ed380c8aceacb35ff91a32-201412291419879205250801.jpg\" title=\"\" longdesc=\"The%20Mississippi%20floodplain%20is%20heavily%20farmed.%20Flooding%20can%20wipe%20out%20farms%20and%20towns%2C%20but%20the%20stream%20also%20deposits%20nutrient-rich%20sediments%20that%20enrich%20the%20floodplain.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtTWlzc2lzc2lwcGktZmxvb2RwbGFpbi5qcGc.\" \/><\/p>\n<p>\n        The Mississippi floodplain is heavily farmed. Flooding can wipe out farms and towns, but the stream also deposits nutrient-rich sediments that enrich the floodplain.\n      <\/p>\n<\/p><\/div>\n<p>\n      A stream at flood stage carries lots of sediments. When its gradient decreases, the stream overflows its banks and broadens its channel. The decrease in gradient causes the stream to deposit its sediments, the largest first. These large sediments build a higher area around the edges of the stream channel, creating <strong>natural levees<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDVh\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"CK-12 Foundation\" --><!-- @@url=\"CK-12 Foundation\" --><!-- @@license=\"CC BY-NC 3.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223708\/201412291419878482980212_a561924b4ceaf08c7b899571e343b28a-201412291419879206088642.jpg\" title=\"\" longdesc=\"After%20many%20floods%2C%20a%20stream%20builds%20natural%20levees%20along%20its%20banks.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDVh\" \/><\/p>\n<p>\n        After many floods, a stream builds natural levees along its banks.\n      <\/p>\n<\/p><\/div>\n<p>\n      When a river enters standing water, its velocity slows to a stop. The stream moves back and forth across the region and drops its sediments in a wide triangular-shaped deposit called a <strong>delta<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMDgtRGVsdGFz\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-fullpage x-ck12-nofloat\">\n      <!-- @@author=\"(a) Courtesy of NASA\/GSFC\/JPL, MISR Team; (b) Courtesy of Robert Simmon\/NASA's Earth Observatory\" --><!-- @@url=\"(a) http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=1234; (b) http:\/\/earthobservatory.nasa.gov\/IOTD\/view.php?id=42439\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223710\/201412291419878483011765_f50c5fec24629d6a4861f93b7add3382-201412291419879206924548.jpg\" title=\"\" longdesc=\"%28a%29%20The%20Nile%20River%20delta%20has%20a%20classic%20triangular%20shape%2C%20like%20the%20capital%20Greek%20letter%20delta.%20%28b%29%20Sediment%20in%20the%20Yellow%20River%20delta.%20The%20main%20stream%20channel%20splits%20into%20many%20smaller%20distributaries.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMDgtRGVsdGFz\" \/><\/p>\n<p>\n        (a) The Nile River delta has a classic triangular shape, like the capital Greek letter delta. (b) Sediment in the Yellow River delta. The main stream channel splits into many smaller distributaries.\n      <\/p>\n<\/p><\/div>\n<p>\n      If a stream falls down a steep slope onto a broad flat valley, an <strong>alluvial fan<\/strong> develops (<strong>Figure<\/strong> <a href=\"#x-ck12-V2VhLTEwMDEtMDg.\">below<\/a>). Alluvial fans generally form in arid regions.\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Courtesy of NASA image created by Jesse Allen, using data from NASA\/GSFC\/METI\/ERSDAC\/JAROS, and the U.S.\/Japan ASTER Science Team\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Alluvial_fan_in_Iran.jpg\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223711\/201412291419878483042055_4bece62103e4791f7e525fe9960b22c4-201412291419879207638346.jpg\" title=\"\" longdesc=\"An%20alluvial%20fan%20in%20Iran.%20The%20mountains%20are%20in%20the%20lower%20right%20corner%20of%20the%20photograph.%20\" alt=\"\" id=\"x-ck12-V2VhLTEwMDEtMDg.\" \/><\/p>\n<p>\n        An alluvial fan in Iran. The mountains are in the lower right corner of the photograph.\n      <\/p>\n<\/p><\/div>\n<h2>\n      Ground Water Erosion and Deposition<br \/>\n    <\/h2>\n<p>\n      Rainwater absorbs carbon dioxide (CO<sub>2<\/sub>) as it falls. The CO<sub>2<\/sub> combines with water to form carbonic acid. The slightly acidic water sinks into the ground and moves through pore spaces in soil and cracks and fractures in rock. The flow of water underground is <strong>ground water.<\/strong>\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"J.B. Martin\" --><!-- @@url=\"CK-12 Foundation\" --><!-- @@license=\"CC BY-NC 3.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223713\/201412291419878483142066_03ae5d7d413fd22431874218b03ec779-201412291419879208235854.jpg\" title=\"\" longdesc=\"When%20water%20sinks%20into%20the%20ground%2C%20it%20becomes%20ground%20water.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMQ..\" \/><\/p>\n<p>\n        When water sinks into the ground, it becomes ground water.\n      <\/p>\n<\/p><\/div>\n<p>\n      Ground water is a strong erosional force, as it works to dissolve away solid rock (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMQ..\">above<\/a>). Carbonic acid is especially good at dissolving the rock limestone.\n    <\/p>\n<h3>\n      Cave Formation<br \/>\n    <\/h3>\n<p>\n      Working slowly over many years, ground water travels along small cracks. The water dissolves and carries away the solid rock gradually enlarging the cracks. Eventually a cave may form (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMg..\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"User:Thelmadatter\/Wikipedia\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:RiverExitTolantongo.JPG\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223714\/201412291419878483165530_75710761d76ec9626e8c165d19f0429e-201412291419879208670231.jpg\" title=\"\" longdesc=\"Caverns%20many%20football%20fields%20long%20and%20as%20high%20as%20many%20meters%20tall%20form%20where%20ground%20water%20erodes%20away%20rock.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMg..\" \/><\/p>\n<p>\n        Caverns many football fields long and as high as many meters tall form where ground water erodes away rock.\n      <\/p>\n<\/p><\/div>\n<p>\n      Ground water carries the dissolved minerals in solution. The minerals may then be deposited, for example, as <strong>stalagmites<\/strong> or <strong>stalactites<\/strong> (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMTAtMTItQ2F2ZS1mb3JtYXRpb24.\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"(a) Dave Pape; (b)  B\u00f6rkur Sigurbj\u00f6rnsson\" --><!-- @@url=\"(a) http:\/\/commons.wikimedia.org\/wiki\/File:Stalactites_-_Treak_Cliff_Cavern.jpg; (b) http:\/\/www.flickr.com\/photos\/borkurdotnet\/2078879358\/\" --><!-- @@license=\"(a) Public Domain; (b) CC BY 2.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223715\/201412291419878483211822_05ee1b404aa683aada01cf76e84d158f-201412291419879209133058.jpg\" title=\"\" longdesc=\"%28a%29%20Stalactites%20form%20as%20calcium%20carbonate%20drips%20from%20the%20ceiling%20of%20a%20cave%2C%20forming%20beautiful%20icicle-like%20formations.%20The%20word%20stalactite%20has%20a%20c%20and%20it%20forms%20from%20the%20ceiling.%20%28b%29%20Stalagmites%20form%20as%20calcium%20carbonate%20drips%20from%20the%20ceiling%20to%20the%20floor%20of%20a%20cave%20and%20then%20grow%20upwards.%20The%20g%20in%20stalagmite%20means%20it%20forms%20on%20the%20ground.%20\" alt=\"\" id=\"x-ck12-SFMtRVMtMTAtMTItQ2F2ZS1mb3JtYXRpb24.\" \/><\/p>\n<p>\n        (a) Stalactites form as calcium carbonate drips from the ceiling of a cave, forming beautiful icicle-like formations. The word stalactite has a c and it forms from the ceiling. (b) Stalagmites form as calcium carbonate drips from the ceiling to the floor of a cave and then grow upwards. The g in stalagmite means it forms on the ground.\n      <\/p>\n<\/p><\/div>\n<p>\n      If a stalactite and stalagmite join together, they form a <strong>column<\/strong>. One of the wonders of visiting a cave is to witness the beauty of these amazing and strangely captivating structures. Caves also produce a beautiful rock, formed from calcium carbonate, <strong>travertine<\/strong>. Ground water saturated with calcium carbonate precipitates as the mineral calcite or aragonite. Mineral springs that produce travertine can be hot, warm or even cold (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wNQ..\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Paul VanDerWerf\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/pavdw\/10644540916\/\" --><!-- @@license=\"CC BY 2.0\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223717\/201412291419878483321754_c86c2ec3dbee94cf88fc4f2028e8648c-201412291419879209697674.jpg\" title=\"\" longdesc=\"Travertine%20is%20a%20beautiful%20form%20of%20limestone.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wNQ..\" \/><\/p>\n<p>\n        Travertine is a beautiful form of limestone.\n      <\/p>\n<\/p><\/div>\n<p>\n      You can explore a fantastic cave, Kartchner Caverns, in Arizona, by watching this video: <a href=\"http:\/\/video.nationalgeographic.com\/video\/player\/science\/earth-sci\/exploring-kartchner-sci.html\">http:\/\/video.nationalgeographic.com\/video\/player\/science\/earth-sci\/exploring-kartchner-sci.html<\/a>\n    <\/p>\n<p>\n      If the roof of a cave collapses, a <strong>sinkhole<\/strong> could form. Some sinkholes are large enough to swallow up a home or several homes in a neighborhood (<strong>Figure<\/strong> <a href=\"#x-ck12-R1ctMTAwMS0wMw..\">below<\/a>).\n    <\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\">\n      <!-- @@author=\"Mason Berry\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:WOAHdubs.jpg\" --><!-- @@license=\"Public Domain\" --><\/p>\n<p>\n        <img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223718\/201412291419878483351294_1941ef423958d4046f9684ebd76dd6dc-201412291419879210717821.jpg\" title=\"\" longdesc=\"This%20sinkhole%20formed%20in%20Florida.%20\" alt=\"\" id=\"x-ck12-R1ctMTAwMS0wMw..\" \/><\/p>\n<p>\n        This sinkhole formed in Florida.\n      <\/p>\n<\/p><\/div>\n<h2>\n      Lesson Summary<br \/>\n    <\/h2>\n<ul>\n<li>Streams erode the land as they move from higher elevations to the sea.\n      <\/li>\n<li>Eroded materials can be carried in a river as dissolved load, suspended load, or bed load.\n      <\/li>\n<li>A river erodes deeply when it is far from its base level, the place where it enters standing water.\n      <\/li>\n<li>Streams form bends, called meanders. Broad, flat areas are known as floodplains.\n      <\/li>\n<li>A delta or an alluvial fan might form where the stream drops its sediment load.\n      <\/li>\n<li>Caves form underground as ground water gradually dissolves away rock.\n      <\/li>\n<\/ul>\n<h2>\n      Review Questions<br \/>\n    <\/h2>\n<ol id=\"x-ck12-MjZhMjU5NDU0NTI3ZjAyOTk0YmZhNGJiYjhkYzJkOWU.-jvd\" class=\"x-ck12-decimal\">\n<li>Define the three kinds of load that make up the particles a stream carries.\n      <\/li>\n<li>What is a stream\u2019s gradient? What effect does it have on the work of a stream?\n      <\/li>\n<li>How do streams erode their beds?\n      <\/li>\n<li>How does a stream produce a wide, flat floodplain?\n      <\/li>\n<li>What type of gradient would a river have when it is actively eroding its stream bed?\n      <\/li>\n<li>When would a river form an alluvial fan and when will it form a delta? Describe the characteristics of each type of deposit.\n      <\/li>\n<li>What are two formations that form inside caves?\n      <\/li>\n<li>What erosional feature formed by ground water could swallow up your house?\n      <\/li>\n<\/ol>\n<h2>\n      Points to Consider<br \/>\n    <\/h2>\n<ul>\n<li>Would a stream at high elevations erode more than a stream at lower elevations?\n      <\/li>\n<li>How would Earth\u2019s surface look without streams?\n      <\/li>\n<li>Would a flash flood along a normally dry river valley be a dangerous event?\n      <\/li>\n<li>Do you think caves could form in your neighborhood?\n      <\/li>\n<\/ul>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-393\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Earth Science for High School. <strong>Provided by<\/strong>: CK-12. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.ck12.org\/book\/CK-12-Earth-Science-For-High-School\/\">http:\/\/www.ck12.org\/book\/CK-12-Earth-Science-For-High-School\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/\">CC BY-NC: Attribution-NonCommercial<\/a><\/em><\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":277,"menu_order":2,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Earth Science for High School\",\"author\":\"\",\"organization\":\"CK-12\",\"url\":\"http:\/\/www.ck12.org\/book\/CK-12-Earth-Science-For-High-School\/\",\"project\":\"\",\"license\":\"cc-by-nc\",\"license_terms\":\"\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-393","chapter","type-chapter","status-publish","hentry"],"part":1284,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/393","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/users\/277"}],"version-history":[{"count":1,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/393\/revisions"}],"predecessor-version":[{"id":1165,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/393\/revisions\/1165"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/parts\/1284"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/393\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/media?parent=393"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapter-type?post=393"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/contributor?post=393"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/license?post=393"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}