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GLACIERS. CHAPTER 5 HONORS EARTH SCIENCE. What is a glacier?. a thick mass of moving ice. http://www.jadecoast.ca/Sawyer%20glacier.JPG. How do glaciers form?. Step 1: Snow accumulates. More snow falls during the winter than melts in the summer. Trans Labrador Highway.

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  2. What is a glacier? a thick mass of moving ice http://www.jadecoast.ca/Sawyer%20glacier.JPG

  3. How do glaciers form? Step 1: Snow accumulates. More snow falls during the winter than melts in the summer.

  4. Trans Labrador Highway

  5. Step 2: Snow changes to firn. As snow accumulates, its weight compress the individual snowflakes to form firn. FIRN http://www.gsw.edu/~bcarter/physgeol/glac/firn.jpg

  6. Firn http://crevassezone.org/Photos/Graphics/3441L-(Firn).jpg

  7. Step 3: Firn is compressed to form solid glacial ice. http://patti.tensegrity.net/album/alaska/thompson/ice4.jpg

  8. http://www.asf.alaska.edu:2222/img/firn_diagram.gifhttp://

  9. Step 4: The ice begins to move. Plastic flow- weight of glacier moves out like pancake batter http://www-math.science.unitn.it/Bike/Countries/Europe/Tour_Reports/Tour_of_the_Alps/Gallery/glacier.jpg

  10. When the climate cooled… Ice advanced over the land, moving southward from Canada over the Great Lakes Region.

  11. Glaciar Perito Moreno, in Santa Cruz province, Argentina. It hasn’t happened since 1988 and it is said to be one of the most extraordinary natural events in the world. - Roberto Cerrudo

  12. Glacier terms • Zone of Ablation- melting • Zone of Accumulation- snow accumulates • Crevasse- cracks • Advance- more accumulation than melting • Retreat- more melting than accumulation

  13. VALLEY GLACIER http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images3/alpine_glacier_processes_side_view_800.jpg

  14. How do glaciers erode the surface? • Plucking –freeze/thaw process lifts particles into ice Striations- parallel scratches made from rocks in ice scraping against bedrock

  15. Glaciers pick up lots of sediment as they advance over the land. http://www.geographyjim.org/Newzealandglacier.jpg

  16. TYPES OF GLACIERS • Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys • Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.

  17. http://daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/GEO_9/geo_images_9/Fig9.20.gifhttp://daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/GEO_9/geo_images_9/Fig9.20.gif

  18. Cirque • A bowl-shaped depression located where a glacier begins to form

  19. http://crevassezone.org/Photos/Graphics/4163L-(Cirque).jpg

  20. Horn Kinnerly Peak - Glacier National Park • A tall, pointed rock peak left at the top of a mountain http://www2.nature.nps.gov/geology//parks/glac/car0348.jpg

  21. The most famous horn in the Alps…The Matterhorn • Located on the boundary between Switzerland and Italy, the Matterhorn’s summit is 4478 m above sea level.

  22. Arete – spines or ridges of rock that separate glacial valleys

  23. U-shaped Valley - Yosemite National Park

  24. V-shaped valleys become U-shaped valleys as glaciers move through them… Step 2 Step 1 A typical river valley Over time, running water cuts a deeper V-shape. Step 3 Glacier fills valley, widening and straightening the channel Step 4 Glaciers melt leaving a U-shaped valley

  25. Hanging Valley • a small valley that has not eroded as deep as the main valley that it is connected to • Waterfalls often form at hanging valleys.

  26. TYPES OF GLACIAL DRIFT(Sediments) • TILL- unsorted; deposited by ice • STRATIFIED DRIFT- layered; deposited by meltwater streams • OUTWASH- sorted sand; deposited by meltwater

  27. Erratics • Boulders carried great distance by the glacier • Don’t match surrounding rock

  28. Erratics along Lake Michigan Shoreline

  29. TYPES OF GLACIERS • Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys • Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.

  30. MORAINES • Deposited along edge of glacier during melting • Terminal- very end of glacier • Lateral- side of glacier • Recessional- progresses behind terminal

  31. MORAINES • MADE OF TILL- unsorted sediment http://www.helsinki.fi/~jhyvonen/PB/M/Cerro%20Tronador%20moraine-pp.JPG

  32. terminal moraine – unsorted sediments deposited at the edge of the melting glacier

  33. Ground Moraine- flat till deposits between recessional moraines

  34. Kettle Lakes • Made from ice blocks

  35. Kettle Lakes • Kettle lakes form when blocks of ice break off the front edge of a glacier, become buried by sediment. The ice melts leaving a hole which fills with water creating a lake.

  36. Drumlins • Hills of sediment deposited by the glacier- till

  37. Winding ridges of stratified drift Deposited by meltwater streams Mined for gravel ESKERS

  38. KAMES Cone shaped deposits Deposited at end of meltwater streams Stratified drift

  39. Why do scientists believe that glaciers once covered Michigan?

  40. Moraine Deposits = unsorted sediments Moraines are made of unsorted sediments. Only mass movements and glaciers deposit unsorted sediments. Since there are no large hills or mountains in Michigan for this sediment to fall down, it must have been deposited by the glaciers.

  41. Moraine Deposits have the same shape as the Great Lakes. • Michigan moraines run parallel to the shoreline. • The same process that formed the moraines formed the Great Lakes.

  42. Each of the Great Lakes began as a river. Image from Earth Science, Tarbuck and Lutgens, 2003

  43. As the climate cooled… • The rivers froze. • Glaciers moved through them – widening and deepening them to form today’s lake bottoms.

  44. The sediment removed from the river valleys was deposited in the moraines covering our state. This is why the moraines run parallel to the shorelines of the Great Lakes.

  45. When the climate began to warm, the glaciers began to melt and retreat. http://www.msstate.edu/dept/geosciences/CT/TIG/WEBSITES/LOCAL/Spring2002/Michael_Marsicek/images/Great_Lakes_Formation.gif

  46. The fresh water from the melting glaciers filled in the deep U-shaped valleys that they had carved and turned them into the lakes we have today. http://www.ofps.ucar.edu/gapp/networks/images/greatlakes_map.jpg

  47. What other evidence do we have that glaciers once covered our state? • Depositional features such as drumlins and kettle lakes. Kalkaska, Michigan

  48. Kettle Lakes

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