{"id":173,"date":"2015-07-10T22:37:14","date_gmt":"2015-07-10T22:37:14","guid":{"rendered":"https:\/\/courses.candelalearning.com\/earthscienceck12\/?post_type=chapter&#038;p=173"},"modified":"2015-07-31T22:41:19","modified_gmt":"2015-07-31T22:41:19","slug":"metamorphic-rocks","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/chapter\/metamorphic-rocks\/","title":{"raw":"Metamorphic Rocks","rendered":"Metamorphic Rocks"},"content":{"raw":"&nbsp;\r\n<h2>Lesson Objectives<\/h2>\r\n<ul>\r\n\t<li>Describe how metamorphic rocks form.<\/li>\r\n\t<li>Describe the properties of some common metamorphic rocks.<\/li>\r\n\t<li>Relate some common uses of metamorphic rocks.<\/li>\r\n<\/ul>\r\n<h2>Vocabulary<\/h2>\r\n<ul>\r\n\t<li>contact metamorphism<\/li>\r\n\t<li>foliation<\/li>\r\n\t<li>regional metamorphism<\/li>\r\n<\/ul>\r\n<h2>Introduction<\/h2>\r\nIn the large outcrop of metamorphic rocks in <strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjctUGxhdHktbWV0YW1vcnBoaWM.\">below<\/a>, the rocks\u2019 platy appearance is a result of the process metamorphism. Metamorphism is the addition of heat and\/or pressure to existing rocks, which causes them to change physically and\/or chemically so that they become a new rock. Metamorphic rocks may change so much that they may not resemble the original rock.\r\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Brian Stansberry\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Chimney-tops-capstone-base1.jpg\" --><!-- @@license=\"CC BY 2.5\" --><img id=\"x-ck12-SFMtRVMtMDQtMDQtMjctUGxhdHktbWV0YW1vcnBoaWM.\" title=\"Example of platy layers in metamorphic rock\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223220\/201412291419878244159903_d5f31268021ba47f3e5411995a253ef9-201412291419879667824619.jpg\" alt=\"Example of platy layers in metamorphic rock\" longdesc=\"The%20platy%20layers%20in%20this%20large%20outcrop%20of%20metamorphic%20rock%20show%20the%20effects%20of%20pressure%20on%20rocks%20during%20metamorphism.%20\" \/>\r\n\r\nThe platy layers in this large outcrop of metamorphic rock show the effects of pressure on rocks during metamorphism.\r\n\r\n<\/div>\r\n<h2>Metamorphism<\/h2>\r\nAny type of rock \u2013 igneous, sedimentary, or metamorphic - can become a metamorphic rock. All that is needed is enough heat and\/or pressure to alter the existing rock\u2019s physical or chemical makeup without melting the rock entirely. Rocks change during metamorphism because the minerals need to be stable under the new temperature and pressure conditions. The need for stability may cause the structure of minerals to rearrange and form new minerals. Ions may move between minerals to create minerals of different chemical composition. Hornfels, with its alternating bands of dark and light crystals, is a good example of how minerals rearrange themselves during metamorphism. Hornfels is shown in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a>.\r\n\r\nExtreme pressure may also lead to <strong>foliation<\/strong>, the flat layers that form in rocks as the rocks are squeezed by pressure (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjgtRm9saWF0ZWQtbWV0YW1vcnBoaWMtcm9jay5wbmc.\">below<\/a>). Foliation normally forms when pressure is exerted in only one direction. Metamorphic rocks may also be non-foliated. Quartzite and limestone, shown in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a>, are nonfoliated.\r\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Jim Kravitz\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/jimmypk\/6094869265\/\" --><!-- @@license=\"CC BY 2.0\" --><img id=\"x-ck12-SFMtRVMtMDQtMDQtMjgtRm9saWF0ZWQtbWV0YW1vcnBoaWMtcm9jay5wbmc.\" title=\"A foliated metamorphic rock\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223223\/201412291419878244258751_1b00fd5585c4c975ec6616ee9f5cae57-201412291419879668789616.jpg\" alt=\"A foliated metamorphic rock\" longdesc=\"A%20foliated%20metamorphic%20rock.%20\" \/>\r\n\r\nA foliated metamorphic rock.\r\n\r\n<\/div>\r\nThe two main types of metamorphism are both related to heat within Earth:\r\n<ol id=\"x-ck12-YjIxM2M3YzNlNzc2ZGM3NTY1YmQzOTU3OTgwNWNkZTg.-cg4\" class=\"x-ck12-decimal\">\r\n\t<li><strong>Regional metamorphism:<\/strong> Changes in enormous quantities of rock over a wide area caused by the extreme pressure from overlying rock or from compression caused by geologic processes. Deep burial exposes the rock to high temperatures.<\/li>\r\n\t<li><strong>Contact metamorphism:<\/strong> Changes in a rock that is in contact with magma because of the magma\u2019s extreme heat.<\/li>\r\n<\/ol>\r\n<strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a> shows some common metamorphic rocks and their original parent rock.\r\n<table id=\"x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\" title=\"Common Metamorphic Rocks\" border=\"1\" summary=\"Common Metamorphic Rocks\">\r\n<thead>\r\n<tr>\r\n<th>Picture<\/th>\r\n<th>Rock Name<\/th>\r\n<th>Type of Metamorphic Rock<\/th>\r\n<th>Comments<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223224\/201412291419878244319677_3df77cdc7f7afb966f5fdd826579a864-201412291419879669134836.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Slate<\/td>\r\n<td>Foliated<\/td>\r\n<td>Metamorphism of shale<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223225\/201412291419878244338130_3f935f4a848330f55589b70654286d1f-201412291419879669791334.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Phyllite<\/td>\r\n<td>Foliated<\/td>\r\n<td>Metamorphism of slate, but under greater heat and pressure than slate<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223227\/201412291419878244365101_a00b3989a5106534aa4e6e36d8dc9e04-201412291419879670539025.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Schist<\/td>\r\n<td>Foliated<\/td>\r\n<td>Often derived from metamorphism of claystone or shale; metamorphosed under more heat and pressure than phyllite<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223228\/201412291419878244464274_5e26197dc61ecc3c47ba76460a23cadc-201412291419879670992271.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Gneiss<\/td>\r\n<td>Foliated<\/td>\r\n<td>Metamorphism of various different rocks, under extreme conditions of heat and pressure<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223230\/201412291419878244482216_3a204384e2f5b443ba89a25f86c44dc3-201412291419879671601388.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Hornfels<\/td>\r\n<td>Non-foliated<\/td>\r\n<td>Contact metamorphism of various different rock types<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223231\/201412291419878244498917_822d242fcf6ba95a5f553d939c258121-201412291419879672275249.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Quartzite<\/td>\r\n<td>Non-foliated<\/td>\r\n<td>Metamorphism of sandstone<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223233\/201412291419878244514689_6b0eb3c05b9b94ddb23f9f837448c0a0-201412291419879672665149.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Marble<\/td>\r\n<td>Non-foliated<\/td>\r\n<td>Metamorphism of limestone<\/td>\r\n<\/tr>\r\n<tr>\r\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223234\/201412291419878244528963_0e81b60857dfe5035c4bdc921291375e-201412291419879672960116.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\r\n<td>Metaconglomerate<\/td>\r\n<td>Non-foliated<\/td>\r\n<td>Metamorphism of conglomerate<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<h2>Uses of Metamorphic Rocks<\/h2>\r\nQuartzite and marble are commonly used for building materials and artwork. Marble is beautiful for statues and decorative items such as vases (see an example in <strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjktTWFyYmxlLXZhc2U.\">below<\/a>). Ground up marble is also a component of toothpaste, plastics, and paper.\r\n<div class=\"x-ck12-img-thumbnail x-ck12-nofloat\"><!-- @@author=\"Vincent de Groot\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Elisabeth02.jpg\" --><!-- @@license=\"CC BY 2.5\" --><img id=\"x-ck12-SFMtRVMtMDQtMDQtMjktTWFyYmxlLXZhc2U.\" title=\"A decorative marble vase\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223235\/201412291419878244551423_2d651f1996a5c4589ea319ccdcbc2f79-201412291419879673376744.jpg\" alt=\"A decorative marble vase\" longdesc=\"Marble%20is%20used%20for%20decorative%20items%20and%20in%20art.%20\" \/>\r\n\r\nMarble is used for decorative items and in art.\r\n\r\n<\/div>\r\nQuartzite is very hard and is often crushed and used in building railroad tracks (see <strong>Figure<\/strong> <a href=\"#x-ck12-RVM0LjQuMTI.\">below<\/a>). Schist and slate are sometimes used as building and landscape materials. Graphite, the \u201clead\u201d in pencils, is a mineral commonly found in metamorphic rocks.\r\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Image copyright Artography, 2014\" --><!-- @@url=\"http:\/\/www.shutterstock.com\" --><!-- @@license=\"Used under license from Shutterstock.com\" --><img id=\"x-ck12-RVM0LjQuMTI.\" title=\"Crushed quartzite under railroad tracks\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223236\/201412291419878244568098_d6a00a4b98f1d9ee84f45f0812ca5423-201412291419879673797712.jpg\" alt=\"Crushed quartzite under railroad tracks\" longdesc=\"Crushed%20quartzite%20is%20sometimes%20placed%20under%20railroad%20tracks%20because%20it%20is%20very%20hard%20and%20durable.%20\" \/>\r\n\r\nCrushed quartzite is sometimes placed under railroad tracks because it is very hard and durable.\r\n\r\n<\/div>\r\n<h2>Lesson Summary<\/h2>\r\n<ul>\r\n\t<li>Metamorphic rocks form when heat and pressure transform an existing rock into a new rock.<\/li>\r\n\t<li>Contact metamorphism occurs when hot magma transforms the rock that it contacts.<\/li>\r\n\t<li>Regional metamorphism transforms large areas of existing rocks under the tremendous heat and pressure created by geologic processes.<\/li>\r\n<\/ul>\r\n<h2>Review Questions<\/h2>\r\n<ol id=\"x-ck12-ZjNhNmE5NTlhOWRlYWI0MGEyYTg1OGVlZjQyYmNiNTg.-qzz\" class=\"x-ck12-decimal\">\r\n\t<li>Why do minerals change composition as they undergo metamorphism?<\/li>\r\n\t<li>Describe the process by which minerals in a rock rearrange to become different minerals when exposed to heat or pressure.<\/li>\r\n\t<li>Describe the conditions that lead to foliated versus non-foliated metamorphic rocks.<\/li>\r\n\t<li>List and describe the two main types of metamorphism.<\/li>\r\n\t<li>What can geologists look at in a metamorphic rock to understand that rock's history?<\/li>\r\n\t<li>Suppose a phyllite sample was metamorphosed again. How might it look different after this second round of metamorphism?<\/li>\r\n<\/ol>\r\n<h2>Further Reading \/ Supplemental Links<\/h2>\r\n<ul>\r\n\t<li><a href=\"http:\/\/media.wr.usgs.gov\/movies\/index.html?id=living_rock\">Film: The Living Rock: Earth\u2019s Continental Crust<\/a>.<\/li>\r\n<\/ul>\r\n<h2>Points to Consider<\/h2>\r\n<ul>\r\n\t<li>What type of rock forms if an existing rock heats up so much that it melts completely and then forms a different rock?<\/li>\r\n\t<li>What clues can a rock give about its history if it was so altered by metamorphism that it is unrecognizable?<\/li>\r\n<\/ul>\r\n&nbsp;\r\n\r\n[footnote]\r\n\r\nFor the rocks in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6c2VkaW1lbnRhcnlfcm9ja3M.\">above<\/a>, from top to bottom:\r\n<ul>\r\n\t<li>Hannes Grobe. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Konglomerat-cyprus1_hg.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Konglomerat-cyprus1_hg.jpg<\/a>. CC BY 3.0.<\/li>\r\n\t<li>Peter Bockstaller. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Rochechouart-Breccia-Chassenon.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Rochechouart-Breccia-Chassenon.jpg<\/a>. CC BY 2.5.<\/li>\r\n\t<li>Courtesy of US GS Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Sandstone%28quartz%29USGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Sandstone%28quartz%29USGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Courtesy of US GS Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:SiltstoneUSGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:SiltstoneUSGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Michael Quinn\/National Park Service. <a href=\"http:\/\/www.flickr.com\/photos\/grand_canyon_nps\/4749606608\/\">http:\/\/www.flickr.com\/photos\/grand_canyon_nps\/4749606608\/<\/a>. CC BY 2.0<\/li>\r\n\t<li>Nate Steiner. <a href=\"http:\/\/www.flickr.com\/photos\/nate\/27476159\/\">http:\/\/www.flickr.com\/photos\/nate\/27476159\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Jeff Barton. <a href=\"http:\/\/www.flickr.com\/photos\/chipdatajeffb\/8269420081\/\">http:\/\/www.flickr.com\/photos\/chipdatajeffb\/8269420081\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>User:Tigerente\/Wikimedia Commons. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:DachsteinkalkBivalvia.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:DachsteinkalkBivalvia.jpg<\/a>. CC BY 2.5.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n<\/ul>\r\n[\/footnote]\r\n\r\n&nbsp;\r\n\r\n[footnote]\r\n\r\nFor the rocks in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">above<\/a>, from top to bottom:\r\n<ul>\r\n\t<li>Erich Ferdinand. <a href=\"http:\/\/www.flickr.com\/photos\/erix\/479616320\/\">http:\/\/www.flickr.com\/photos\/erix\/479616320\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Courtesy of US Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:PhylliteUSGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:PhylliteUSGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Image copyright Marafona, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>User:Huhulenik\/Wikimedia Commons. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Orthogneiss_Geopark.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Orthogneiss_Geopark.jpg<\/a>. CC BY 3.0.<\/li>\r\n\t<li>User:Fed\/Ru.Wikipedia. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Hornfels.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Hornfels.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>Mark A. Wilson (User:Wilson44691\/Wikimedia Commons). <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Metaconglomerate112709.JPG\">http:\/\/commons.wikimedia.org\/wiki\/File:Metaconglomerate112709.JPG<\/a>. Public Domain.<\/li>\r\n<\/ul>\r\n[\/footnote]\r\n\r\n&nbsp;","rendered":"<p>&nbsp;<\/p>\n<h2>Lesson Objectives<\/h2>\n<ul>\n<li>Describe how metamorphic rocks form.<\/li>\n<li>Describe the properties of some common metamorphic rocks.<\/li>\n<li>Relate some common uses of metamorphic rocks.<\/li>\n<\/ul>\n<h2>Vocabulary<\/h2>\n<ul>\n<li>contact metamorphism<\/li>\n<li>foliation<\/li>\n<li>regional metamorphism<\/li>\n<\/ul>\n<h2>Introduction<\/h2>\n<p>In the large outcrop of metamorphic rocks in <strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjctUGxhdHktbWV0YW1vcnBoaWM.\">below<\/a>, the rocks\u2019 platy appearance is a result of the process metamorphism. Metamorphism is the addition of heat and\/or pressure to existing rocks, which causes them to change physically and\/or chemically so that they become a new rock. Metamorphic rocks may change so much that they may not resemble the original rock.<\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Brian Stansberry\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Chimney-tops-capstone-base1.jpg\" --><!-- @@license=\"CC BY 2.5\" --><img decoding=\"async\" id=\"x-ck12-SFMtRVMtMDQtMDQtMjctUGxhdHktbWV0YW1vcnBoaWM.\" title=\"Example of platy layers in metamorphic rock\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223220\/201412291419878244159903_d5f31268021ba47f3e5411995a253ef9-201412291419879667824619.jpg\" alt=\"Example of platy layers in metamorphic rock\" longdesc=\"The%20platy%20layers%20in%20this%20large%20outcrop%20of%20metamorphic%20rock%20show%20the%20effects%20of%20pressure%20on%20rocks%20during%20metamorphism.%20\" \/><\/p>\n<p>The platy layers in this large outcrop of metamorphic rock show the effects of pressure on rocks during metamorphism.<\/p>\n<\/div>\n<h2>Metamorphism<\/h2>\n<p>Any type of rock \u2013 igneous, sedimentary, or metamorphic &#8211; can become a metamorphic rock. All that is needed is enough heat and\/or pressure to alter the existing rock\u2019s physical or chemical makeup without melting the rock entirely. Rocks change during metamorphism because the minerals need to be stable under the new temperature and pressure conditions. The need for stability may cause the structure of minerals to rearrange and form new minerals. Ions may move between minerals to create minerals of different chemical composition. Hornfels, with its alternating bands of dark and light crystals, is a good example of how minerals rearrange themselves during metamorphism. Hornfels is shown in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a>.<\/p>\n<p>Extreme pressure may also lead to <strong>foliation<\/strong>, the flat layers that form in rocks as the rocks are squeezed by pressure (<strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjgtRm9saWF0ZWQtbWV0YW1vcnBoaWMtcm9jay5wbmc.\">below<\/a>). Foliation normally forms when pressure is exerted in only one direction. Metamorphic rocks may also be non-foliated. Quartzite and limestone, shown in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a>, are nonfoliated.<\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Jim Kravitz\" --><!-- @@url=\"http:\/\/www.flickr.com\/photos\/jimmypk\/6094869265\/\" --><!-- @@license=\"CC BY 2.0\" --><img decoding=\"async\" id=\"x-ck12-SFMtRVMtMDQtMDQtMjgtRm9saWF0ZWQtbWV0YW1vcnBoaWMtcm9jay5wbmc.\" title=\"A foliated metamorphic rock\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223223\/201412291419878244258751_1b00fd5585c4c975ec6616ee9f5cae57-201412291419879668789616.jpg\" alt=\"A foliated metamorphic rock\" longdesc=\"A%20foliated%20metamorphic%20rock.%20\" \/><\/p>\n<p>A foliated metamorphic rock.<\/p>\n<\/div>\n<p>The two main types of metamorphism are both related to heat within Earth:<\/p>\n<ol id=\"x-ck12-YjIxM2M3YzNlNzc2ZGM3NTY1YmQzOTU3OTgwNWNkZTg.-cg4\" class=\"x-ck12-decimal\">\n<li><strong>Regional metamorphism:<\/strong> Changes in enormous quantities of rock over a wide area caused by the extreme pressure from overlying rock or from compression caused by geologic processes. Deep burial exposes the rock to high temperatures.<\/li>\n<li><strong>Contact metamorphism:<\/strong> Changes in a rock that is in contact with magma because of the magma\u2019s extreme heat.<\/li>\n<\/ol>\n<p><strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">below<\/a> shows some common metamorphic rocks and their original parent rock.<\/p>\n<table id=\"x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\" title=\"Common Metamorphic Rocks\" summary=\"Common Metamorphic Rocks\">\n<thead>\n<tr>\n<th>Picture<\/th>\n<th>Rock Name<\/th>\n<th>Type of Metamorphic Rock<\/th>\n<th>Comments<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223224\/201412291419878244319677_3df77cdc7f7afb966f5fdd826579a864-201412291419879669134836.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Slate<\/td>\n<td>Foliated<\/td>\n<td>Metamorphism of shale<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223225\/201412291419878244338130_3f935f4a848330f55589b70654286d1f-201412291419879669791334.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Phyllite<\/td>\n<td>Foliated<\/td>\n<td>Metamorphism of slate, but under greater heat and pressure than slate<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223227\/201412291419878244365101_a00b3989a5106534aa4e6e36d8dc9e04-201412291419879670539025.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Schist<\/td>\n<td>Foliated<\/td>\n<td>Often derived from metamorphism of claystone or shale; metamorphosed under more heat and pressure than phyllite<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223228\/201412291419878244464274_5e26197dc61ecc3c47ba76460a23cadc-201412291419879670992271.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Gneiss<\/td>\n<td>Foliated<\/td>\n<td>Metamorphism of various different rocks, under extreme conditions of heat and pressure<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223230\/201412291419878244482216_3a204384e2f5b443ba89a25f86c44dc3-201412291419879671601388.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Hornfels<\/td>\n<td>Non-foliated<\/td>\n<td>Contact metamorphism of various different rock types<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223231\/201412291419878244498917_822d242fcf6ba95a5f553d939c258121-201412291419879672275249.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Quartzite<\/td>\n<td>Non-foliated<\/td>\n<td>Metamorphism of sandstone<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223233\/201412291419878244514689_6b0eb3c05b9b94ddb23f9f837448c0a0-201412291419879672665149.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Marble<\/td>\n<td>Non-foliated<\/td>\n<td>Metamorphism of limestone<\/td>\n<\/tr>\n<tr>\n<td><span class=\"x-ck12-img-inline\"><!-- @@author=\"\" --><!-- @@license=\"\" --> <img decoding=\"async\" title=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223234\/201412291419878244528963_0e81b60857dfe5035c4bdc921291375e-201412291419879672960116.jpg\" alt=\"\" longdesc=\"\" \/><\/span><\/td>\n<td>Metaconglomerate<\/td>\n<td>Non-foliated<\/td>\n<td>Metamorphism of conglomerate<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Uses of Metamorphic Rocks<\/h2>\n<p>Quartzite and marble are commonly used for building materials and artwork. Marble is beautiful for statues and decorative items such as vases (see an example in <strong>Figure<\/strong> <a href=\"#x-ck12-SFMtRVMtMDQtMDQtMjktTWFyYmxlLXZhc2U.\">below<\/a>). Ground up marble is also a component of toothpaste, plastics, and paper.<\/p>\n<div class=\"x-ck12-img-thumbnail x-ck12-nofloat\"><!-- @@author=\"Vincent de Groot\" --><!-- @@url=\"http:\/\/commons.wikimedia.org\/wiki\/File:Elisabeth02.jpg\" --><!-- @@license=\"CC BY 2.5\" --><img decoding=\"async\" id=\"x-ck12-SFMtRVMtMDQtMDQtMjktTWFyYmxlLXZhc2U.\" title=\"A decorative marble vase\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223235\/201412291419878244551423_2d651f1996a5c4589ea319ccdcbc2f79-201412291419879673376744.jpg\" alt=\"A decorative marble vase\" longdesc=\"Marble%20is%20used%20for%20decorative%20items%20and%20in%20art.%20\" \/><\/p>\n<p>Marble is used for decorative items and in art.<\/p>\n<\/div>\n<p>Quartzite is very hard and is often crushed and used in building railroad tracks (see <strong>Figure<\/strong> <a href=\"#x-ck12-RVM0LjQuMTI.\">below<\/a>). Schist and slate are sometimes used as building and landscape materials. Graphite, the \u201clead\u201d in pencils, is a mineral commonly found in metamorphic rocks.<\/p>\n<div class=\"x-ck12-img-postcard x-ck12-nofloat\"><!-- @@author=\"Image copyright Artography, 2014\" --><!-- @@url=\"http:\/\/www.shutterstock.com\" --><!-- @@license=\"Used under license from Shutterstock.com\" --><img decoding=\"async\" id=\"x-ck12-RVM0LjQuMTI.\" title=\"Crushed quartzite under railroad tracks\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/682\/2015\/07\/22223236\/201412291419878244568098_d6a00a4b98f1d9ee84f45f0812ca5423-201412291419879673797712.jpg\" alt=\"Crushed quartzite under railroad tracks\" longdesc=\"Crushed%20quartzite%20is%20sometimes%20placed%20under%20railroad%20tracks%20because%20it%20is%20very%20hard%20and%20durable.%20\" \/><\/p>\n<p>Crushed quartzite is sometimes placed under railroad tracks because it is very hard and durable.<\/p>\n<\/div>\n<h2>Lesson Summary<\/h2>\n<ul>\n<li>Metamorphic rocks form when heat and pressure transform an existing rock into a new rock.<\/li>\n<li>Contact metamorphism occurs when hot magma transforms the rock that it contacts.<\/li>\n<li>Regional metamorphism transforms large areas of existing rocks under the tremendous heat and pressure created by geologic processes.<\/li>\n<\/ul>\n<h2>Review Questions<\/h2>\n<ol id=\"x-ck12-ZjNhNmE5NTlhOWRlYWI0MGEyYTg1OGVlZjQyYmNiNTg.-qzz\" class=\"x-ck12-decimal\">\n<li>Why do minerals change composition as they undergo metamorphism?<\/li>\n<li>Describe the process by which minerals in a rock rearrange to become different minerals when exposed to heat or pressure.<\/li>\n<li>Describe the conditions that lead to foliated versus non-foliated metamorphic rocks.<\/li>\n<li>List and describe the two main types of metamorphism.<\/li>\n<li>What can geologists look at in a metamorphic rock to understand that rock&#8217;s history?<\/li>\n<li>Suppose a phyllite sample was metamorphosed again. How might it look different after this second round of metamorphism?<\/li>\n<\/ol>\n<h2>Further Reading \/ Supplemental Links<\/h2>\n<ul>\n<li><a href=\"http:\/\/media.wr.usgs.gov\/movies\/index.html?id=living_rock\">Film: The Living Rock: Earth\u2019s Continental Crust<\/a>.<\/li>\n<\/ul>\n<h2>Points to Consider<\/h2>\n<ul>\n<li>What type of rock forms if an existing rock heats up so much that it melts completely and then forms a different rock?<\/li>\n<li>What clues can a rock give about its history if it was so altered by metamorphism that it is unrecognizable?<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><a class=\"footnote\" title=\"For the rocks in Table above, from top to bottom:\n\n\tHannes Grobe. http:\/\/commons.wikimedia.org\/wiki\/File:Konglomerat-cyprus1_hg.jpg. CC BY 3.0.\n\tPeter Bockstaller. http:\/\/commons.wikimedia.org\/wiki\/File:Rochechouart-Breccia-Chassenon.jpg. CC BY 2.5.\n\tCourtesy of US GS Geological Survey and Mineral Information Institute. http:\/\/commons.wikimedia.org\/wiki\/File:Sandstone%28quartz%29USGOV.jpg. Public Domain.\n\tCourtesy of US GS Geological Survey and Mineral Information Institute. http:\/\/commons.wikimedia.org\/wiki\/File:SiltstoneUSGOV.jpg. Public Domain.\n\tMichael Quinn\/National Park Service. http:\/\/www.flickr.com\/photos\/grand_canyon_nps\/4749606608\/. CC BY 2.0\n\tNate Steiner. http:\/\/www.flickr.com\/photos\/nate\/27476159\/. CC BY 2.0.\n\tJeff Barton. http:\/\/www.flickr.com\/photos\/chipdatajeffb\/8269420081\/. CC BY 2.0.\n\tImage copyright Tyler Boyes, 2014. http:\/\/www.shutterstock.com. Used under license from Shutterstock.com.\n\tUser:Tigerente\/Wikimedia Commons. http:\/\/commons.wikimedia.org\/wiki\/File:DachsteinkalkBivalvia.jpg. CC BY 2.5.\n\tImage copyright Tyler Boyes, 2014. http:\/\/www.shutterstock.com. Used under license from Shutterstock.com.\" id=\"return-footnote-173-1\" href=\"#footnote-173-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a><\/p>\n<p>&nbsp;<\/p>\n<p><a class=\"footnote\" title=\"For the rocks in Table above, from top to bottom:\n\n\tErich Ferdinand. http:\/\/www.flickr.com\/photos\/erix\/479616320\/. CC BY 2.0.\n\tCourtesy of US Geological Survey and Mineral Information Institute. http:\/\/commons.wikimedia.org\/wiki\/File:PhylliteUSGOV.jpg. Public Domain.\n\tImage copyright Marafona, 2014. http:\/\/www.shutterstock.com. Used under license from Shutterstock.com.\n\tUser:Huhulenik\/Wikimedia Commons. http:\/\/commons.wikimedia.org\/wiki\/File:Orthogneiss_Geopark.jpg. CC BY 3.0.\n\tUser:Fed\/Ru.Wikipedia. http:\/\/commons.wikimedia.org\/wiki\/File:Hornfels.jpg. Public Domain.\n\tImage copyright Tyler Boyes, 2014. http:\/\/www.shutterstock.com. Used under license from Shutterstock.com.\n\tImage copyright Tyler Boyes, 2014. http:\/\/www.shutterstock.com. Used under license from Shutterstock.com.\n\tMark A. Wilson (User:Wilson44691\/Wikimedia Commons). http:\/\/commons.wikimedia.org\/wiki\/File:Metaconglomerate112709.JPG. Public Domain.\" id=\"return-footnote-173-2\" href=\"#footnote-173-2\" aria-label=\"Footnote 2\"><sup class=\"footnote\">[2]<\/sup><\/a><\/p>\n<p>&nbsp;<\/p>\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-173\">\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><hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-173-1\">\r\n\r\nFor the rocks in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6c2VkaW1lbnRhcnlfcm9ja3M.\">above<\/a>, from top to bottom:\r\n<ul>\r\n\t<li>Hannes Grobe. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Konglomerat-cyprus1_hg.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Konglomerat-cyprus1_hg.jpg<\/a>. CC BY 3.0.<\/li>\r\n\t<li>Peter Bockstaller. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Rochechouart-Breccia-Chassenon.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Rochechouart-Breccia-Chassenon.jpg<\/a>. CC BY 2.5.<\/li>\r\n\t<li>Courtesy of US GS Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Sandstone%28quartz%29USGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Sandstone%28quartz%29USGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Courtesy of US GS Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:SiltstoneUSGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:SiltstoneUSGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Michael Quinn\/National Park Service. <a href=\"http:\/\/www.flickr.com\/photos\/grand_canyon_nps\/4749606608\/\">http:\/\/www.flickr.com\/photos\/grand_canyon_nps\/4749606608\/<\/a>. CC BY 2.0<\/li>\r\n\t<li>Nate Steiner. <a href=\"http:\/\/www.flickr.com\/photos\/nate\/27476159\/\">http:\/\/www.flickr.com\/photos\/nate\/27476159\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Jeff Barton. <a href=\"http:\/\/www.flickr.com\/photos\/chipdatajeffb\/8269420081\/\">http:\/\/www.flickr.com\/photos\/chipdatajeffb\/8269420081\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>User:Tigerente\/Wikimedia Commons. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:DachsteinkalkBivalvia.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:DachsteinkalkBivalvia.jpg<\/a>. CC BY 2.5.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n<\/ul>\r\n <a href=\"#return-footnote-173-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><li id=\"footnote-173-2\">\r\n\r\nFor the rocks in <strong>Table<\/strong> <a href=\"#x-ck12-dGFibGU6bWV0YW1vcnBoaWNfcm9ja3M.\">above<\/a>, from top to bottom:\r\n<ul>\r\n\t<li>Erich Ferdinand. <a href=\"http:\/\/www.flickr.com\/photos\/erix\/479616320\/\">http:\/\/www.flickr.com\/photos\/erix\/479616320\/<\/a>. CC BY 2.0.<\/li>\r\n\t<li>Courtesy of US Geological Survey and Mineral Information Institute. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:PhylliteUSGOV.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:PhylliteUSGOV.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Image copyright Marafona, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>User:Huhulenik\/Wikimedia Commons. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Orthogneiss_Geopark.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Orthogneiss_Geopark.jpg<\/a>. CC BY 3.0.<\/li>\r\n\t<li>User:Fed\/Ru.Wikipedia. <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Hornfels.jpg\">http:\/\/commons.wikimedia.org\/wiki\/File:Hornfels.jpg<\/a>. Public Domain.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>Image copyright Tyler Boyes, 2014. <a href=\"http:\/\/www.shutterstock.com\">http:\/\/www.shutterstock.com<\/a>. Used under license from Shutterstock.com.<\/li>\r\n\t<li>Mark A. Wilson (User:Wilson44691\/Wikimedia Commons). <a href=\"http:\/\/commons.wikimedia.org\/wiki\/File:Metaconglomerate112709.JPG\">http:\/\/commons.wikimedia.org\/wiki\/File:Metaconglomerate112709.JPG<\/a>. Public Domain.<\/li>\r\n<\/ul>\r\n <a href=\"#return-footnote-173-2\" class=\"return-footnote\" aria-label=\"Return to footnote 2\">&crarr;<\/a><\/li><\/ol><\/div>","protected":false},"author":277,"menu_order":7,"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-173","chapter","type-chapter","status-publish","hentry"],"part":1290,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/173","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":3,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/173\/revisions"}],"predecessor-version":[{"id":1338,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/173\/revisions\/1338"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/parts\/1290"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapters\/173\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/media?parent=173"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/pressbooks\/v2\/chapter-type?post=173"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/contributor?post=173"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/earthscienceck12\/wp-json\/wp\/v2\/license?post=173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}