Glaciers & Glaciation GLG Physical Geology Bob Leighty These lecture notes are very similar to the ones I use in my traditional classes. Youll find they are loaded with imagery and streamlined text that highlight the most essential terms and concepts. The notes provide a framework for learning and, by themselves, are not meant to be a comprehensive source of information. To take advantage of the global knowledge base known as the Internet, I have included numerous hyperlinks to external web sites (like the Wikipedia, USGS, NASA, etc.). Follow the links and scan them for relevant info. The information from linked web sites is meant to supplement and reinforce the lecture notes you wont be responsible for knowing everything contained in them. As a distance learning student, you need to explore and understand the content more independently than in a traditional class. As always, I will help guide you through this learning adventure. Remember,Dr. Bob if you have any questions about todays lecture Leave no questions behind! Explore and have fun! These notes and web links are your primary lecture content in this class. Additionally, various articles are assigned each week to supplement this lecture information. I believe youll have enough information to reference without having to purchase a costly textbook. Fiction - There was one great Ice Age in the pastIce Age Glaciation Misconceptions Glaciers & Glaciations Fact There have been many Ice Ages (2 Ga, 600 Ma, 400 Ma, 3 Ma) Fiction If all the ice melted, wed all drown! Glaciation Misconceptions Glaciers & Glaciations Fiction If all the ice melted, wed all drown! Fact Global mean sea level would rise ~70 m (~230 ft) Glaciation Misconceptions Glaciers & Glaciations Fiction North America was entirely covered by ice during the last Ice Age Glaciation Misconceptions Glaciers & Glaciations Fiction North America was entirely covered by ice during the last glaciation Fact Not even close! Glaciation Misconceptions Glaciers & Glaciations A thick mass of compacted snow & ice Flows under its own weight What is a Glacier? Glaciers & Glaciations Forms on land (ice shelves form over water) How Do Glaciers Form? Glaciers & Glaciations How Do Glaciers Move? Glaciers & Glaciations How Do Glaciers Move? Glaciers & Glaciations Where Do Glaciers Form? Glaciers & Glaciations Examples: Antarctica, GreenlandAntarcticaGreenland Large ones at high latitudes (near the poles) Examples: Alps, Himalayas, Andes, etc.AlpsHimalayasAndes Smaller ones in mountainous areas Where Do Glaciers Form? Glaciers & Glaciations On other worlds Extraterrestrial Ice Glaciers & Glaciations Examples: Mars, EuropaMarsEuropa Types of Glaciers Glaciers & Glaciations Alpine Form in mountainous terrain Types of Glaciers Glaciers & Glaciations Alpine Erosion Caused by rock in the ice, not the ice itself Types of Glaciers Glaciers & Glaciations Alpine Erosion U-shaped valleys Glacier-carved valleys U-shaped valleys Types of Glaciers Glaciers & Glaciations Alpine Erosion Fjords - U-shaped valleys flooded by the sea Fjords Types of Glaciers Glaciers & Glaciations Alpine Erosion Cirques Bowl-shaped hollows where glaciers originate Cirques Types of Glaciers Glaciers & Glaciations Alpine Erosion Horns & Aretes Peaks & ridges formed by 2 or more glaciers HornsAretes Types of Glaciers Glaciers & Glaciations Alpine Erosion Striations Grooves etched into bedrock by icebound rock debris Striations >Help determine flow direction (in ancient rocks, too) Types of Glaciers Glaciers & Glaciations Alpine Deposition Moraine Unconsolidated material deposited by glacial ice Moraine Glacial till Unsorted debris Glacial till Types of Glaciers Glaciers & Glaciations Continental Ice Sheets Ice covering vast land areas Types of Glaciers Glaciers & Glaciations Continental Ice Sheets Erosion Striations Types of Glaciers Glaciers & Glaciations Continental Ice Sheets Deposition Drift = Glacial till (ice-deposited) & outwash (stream-deposited) Causes of Glaciation Glaciers & Glaciations 1) Continents collect at high latitudes (at the poles) 2) Ocean circulation patterns 3) Variations in Earths orbital dynamics a)orbit shape more elliptical b)changes in tilt of rotation axis c)precession of the axis Causes of Glaciation Glaciers & Glaciations Meteorites collect along mountain ranges as ice is sublimated off by strong winds Meteoritessublimated Antarctic Meteorites Glaciers & Glaciations WWW Links in this Lecture > Ice Age -> Glacier -> Antarctica -> Greenland -> Alps -> Himalayas -> Andes -> Martian north polar ice cap -> Europa -> U-shaped valleys -> Fjord -> Cirque - > Horn -> Arete -> Glacial striation -Glaciers & Glaciations WWW Links in this Lecture > Moraine -> Glacial till -> Ice sheet -> Milankovitch cycles -> Antarctic meteorites -> The Antarctic Search for Meteorites -> Sublimation -Glaciers & Glaciations