{"id":697,"date":"2019-06-11T14:52:33","date_gmt":"2019-06-11T14:52:33","guid":{"rendered":"https:\/\/opentextbc.ca\/physicalgeology2ed\/part\/chapter-16-glaciation\/"},"modified":"2021-12-08T20:44:28","modified_gmt":"2021-12-08T20:44:28","slug":"chapter-16-glaciation","status":"publish","type":"part","link":"https:\/\/opentextbc.ca\/physicalgeology2ed\/part\/chapter-16-glaciation\/","title":{"raw":"Chapter 16 Glaciation","rendered":"Chapter 16 Glaciation"},"content":{"raw":"<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\">Learning Objectives<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nAfter reading this chapter, completing the exercises within it, and answering the questions at the end, you should be able to:\r\n<ul>\r\n \t<li>Describe the timing and extent of Earth\u2019s past glaciations, going as far back as the early Proterozoic.<\/li>\r\n \t<li>Describe the important geological events that led up to the Pleistocene glaciations and how the Milankovitch orbital variations along with positive feedback mechanisms have controlled the timing of those glaciations.<\/li>\r\n \t<li>Explain the differences between continental and alpine glaciation.<\/li>\r\n \t<li>Summarize how snow and ice accumulate above the equilibrium line and are converted to ice.<\/li>\r\n \t<li>Explain how basal sliding and internal flow facilitate the movement of ice from the upper part to the lower part of a glacier.<\/li>\r\n \t<li>Describe and identify the various landforms related to alpine glacial erosion, including U-shaped valleys, ar\u00eates, cols, horns, hanging valleys, truncated spurs, drumlins, roches mouton\u00e9es, glacial grooves, and striae.<\/li>\r\n \t<li>Identify various types of glacial lakes, including tarns, finger lakes, moraine lakes, and kettle lakes.<\/li>\r\n \t<li>Describe the nature and origins of lodgement till, ablation till, and glaciofluvial, glaciolacustrine, and glaciomarine sediments.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n\r\n[caption id=\"attachment_696\" align=\"aligncenter\" width=\"900\"]<a href=\"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2.png\"><img class=\"wp-image-696\" src=\"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2.png\" alt=\"\" width=\"900\" height=\"394\" \/><\/a> Figure 16.0.1 Glaciers in the Alberta Rockies: Athabasca Glacier (centre left), Dome Glacier (right), and the Columbia Icefield (visible above both glaciers). The Athabasca Glacier has prominent lateral moraines on both sides.[\/caption]\r\n\r\nA <strong>[pb_glossary id=\"1822\"]glacier[\/pb_glossary]<\/strong> is a long-lasting body of ice (decades or more) that is large enough (at least tens of metres thick and at least hundreds of metres in extent) to move under its own weight. About 10% of Earth\u2019s land surface is currently covered with glacial ice, and although the vast majority of that is in Antarctica and Greenland, there are many glaciers in Canada, especially in the mountainous parts of B.C., Alberta, and Yukon and in the far north (Figure 16.0.1). At various times during the past million years, glacial ice has been much more extensive, covering at least 30% of the land surface at times.\r\n\r\nGlaciers represent the largest repository of fresh water on Earth (~69% of all fresh water), and they are highly sensitive to changes in climate. In the current warming climate, glaciers are melting rapidly worldwide, and although some of the larger glacial masses will last for centuries more, many smaller glaciers, including many in western Canada, will be gone within decades, and in some cases, within years. That is much more than just a troubling thought and a scenic loss for western Canadians because we rely on glacial ice for our water supplies\u2014if not for water to drink, then for water to grow food. Irrigation systems in B.C. and across Alberta and Saskatchewan are replenished by meltwater originating from glaciers in the Coast Range and the Rocky Mountains.\r\n<h3>Media Attributions<\/h3>\r\n<ul>\r\n \t<li>Figure 16.0.1: \u00a9 Steven Earle. CC BY.<\/li>\r\n<\/ul>","rendered":"<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\">Learning Objectives<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>After reading this chapter, completing the exercises within it, and answering the questions at the end, you should be able to:<\/p>\n<ul>\n<li>Describe the timing and extent of Earth\u2019s past glaciations, going as far back as the early Proterozoic.<\/li>\n<li>Describe the important geological events that led up to the Pleistocene glaciations and how the Milankovitch orbital variations along with positive feedback mechanisms have controlled the timing of those glaciations.<\/li>\n<li>Explain the differences between continental and alpine glaciation.<\/li>\n<li>Summarize how snow and ice accumulate above the equilibrium line and are converted to ice.<\/li>\n<li>Explain how basal sliding and internal flow facilitate the movement of ice from the upper part to the lower part of a glacier.<\/li>\n<li>Describe and identify the various landforms related to alpine glacial erosion, including U-shaped valleys, ar\u00eates, cols, horns, hanging valleys, truncated spurs, drumlins, roches mouton\u00e9es, glacial grooves, and striae.<\/li>\n<li>Identify various types of glacial lakes, including tarns, finger lakes, moraine lakes, and kettle lakes.<\/li>\n<li>Describe the nature and origins of lodgement till, ablation till, and glaciofluvial, glaciolacustrine, and glaciomarine sediments.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<figure id=\"attachment_696\" aria-describedby=\"caption-attachment-696\" style=\"width: 900px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-696\" src=\"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2.png\" alt=\"\" width=\"900\" height=\"394\" srcset=\"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2.png 1241w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-300x131.png 300w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-768x336.png 768w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-1024x448.png 1024w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-65x28.png 65w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-225x98.png 225w, https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-content\/uploads\/sites\/298\/2019\/06\/athabasca-2-350x153.png 350w\" sizes=\"auto, (max-width: 900px) 100vw, 900px\" \/><\/a><figcaption id=\"caption-attachment-696\" class=\"wp-caption-text\">Figure 16.0.1 Glaciers in the Alberta Rockies: Athabasca Glacier (centre left), Dome Glacier (right), and the Columbia Icefield (visible above both glaciers). The Athabasca Glacier has prominent lateral moraines on both sides.<\/figcaption><\/figure>\n<p>A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_697_1822\">glacier<\/a><\/strong> is a long-lasting body of ice (decades or more) that is large enough (at least tens of metres thick and at least hundreds of metres in extent) to move under its own weight. About 10% of Earth\u2019s land surface is currently covered with glacial ice, and although the vast majority of that is in Antarctica and Greenland, there are many glaciers in Canada, especially in the mountainous parts of B.C., Alberta, and Yukon and in the far north (Figure 16.0.1). At various times during the past million years, glacial ice has been much more extensive, covering at least 30% of the land surface at times.<\/p>\n<p>Glaciers represent the largest repository of fresh water on Earth (~69% of all fresh water), and they are highly sensitive to changes in climate. In the current warming climate, glaciers are melting rapidly worldwide, and although some of the larger glacial masses will last for centuries more, many smaller glaciers, including many in western Canada, will be gone within decades, and in some cases, within years. That is much more than just a troubling thought and a scenic loss for western Canadians because we rely on glacial ice for our water supplies\u2014if not for water to drink, then for water to grow food. Irrigation systems in B.C. and across Alberta and Saskatchewan are replenished by meltwater originating from glaciers in the Coast Range and the Rocky Mountains.<\/p>\n<h3>Media Attributions<\/h3>\n<ul>\n<li>Figure 16.0.1: \u00a9 Steven Earle. CC BY.<\/li>\n<\/ul>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_697_1822\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_697_1822\"><div tabindex=\"-1\"><p>a long lasting (centuries or more) body of ice on land that moves under its own weight<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"parent":0,"menu_order":16,"template":"","meta":{"pb_part_invisible":false,"pb_part_invisible_string":""},"contributor":[],"license":[],"class_list":["post-697","part","type-part","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/pressbooks\/v2\/parts\/697","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/pressbooks\/v2\/parts"}],"about":[{"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/wp\/v2\/types\/part"}],"version-history":[{"count":3,"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/pressbooks\/v2\/parts\/697\/revisions"}],"predecessor-version":[{"id":2353,"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/pressbooks\/v2\/parts\/697\/revisions\/2353"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/wp\/v2\/media?parent=697"}],"wp:term":[{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/wp\/v2\/contributor?post=697"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/physicalgeology2ed\/wp-json\/wp\/v2\/license?post=697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}