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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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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.
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
Firn http://crevassezone.org/Photos/Graphics/3441L-(Firn).jpg
Step 3: Firn is compressed to form solid glacial ice. http://patti.tensegrity.net/album/alaska/thompson/ice4.jpg
http://www.asf.alaska.edu:2222/img/firn_diagram.gifhttp://207.239.98.44/IcelandI%20232.jpghttp://www.asf.alaska.edu:2222/img/firn_diagram.gifhttp://207.239.98.44/IcelandI%20232.jpg
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
When the climate cooled… Ice advanced over the land, moving southward from Canada over the Great Lakes Region.
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
Glacier terms • Zone of Ablation- melting • Zone of Accumulation- snow accumulates • Crevasse- cracks • Advance- more accumulation than melting • Retreat- more melting than accumulation
VALLEY GLACIER http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images3/alpine_glacier_processes_side_view_800.jpg
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
Glacial Striations Granite Island, Lake Superior MI Calumet, MI N47°14’77’’ W88°26’82’’
TYPES OF GLACIERS • Alpine (Valley)Glaciers – glaciers that form at high elevation in mountain valleys • Ice sheets or Continental Glaciers.
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
Cirque • A bowl-shaped depression located where a glacier begins to form
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
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.
Arete – spines or ridges of rock that separate glacial valleys
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
Glaciers pick up lots of sediment as they advance over the land. http://www.geographyjim.org/Newzealandglacier.jpg
TYPES OF GLACIAL DRIFT(Sediments) • TILL- unsorted; deposited by ice • STRATIFIED DRIFT- layered; deposited by meltwater streams • OUTWASH- sorted sand; deposited by meltwater
Erratics • Boulders carried great distance by the glacier • Don’t match surrounding rock
TYPES OF GLACIERS • Alpine (Valley)Glaciers – • Ice sheets or Continental Glaciers form in polar regions such as Greenland and Antarctica.
MORAINES • MADE OF TILL • Deposited along edge of glacier during melting http://www.helsinki.fi/~jhyvonen/PB/M/Cerro%20Tronador%20moraine-pp.JPG
MORAINES • Terminal- very end of glacier • Lateral- side of glacier • Recessional- progresses behind terminal
Ground Moraine- flat till deposits between recessional moraines
Kettle Lakes • Made from ice blocks
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.
Drumlins • Hills of sediment deposited by the glacier- till
Winding ridges of stratified drift Deposited by meltwater streams Mined for gravel ESKERS
KAMES Cone shaped deposits Deposited at end of meltwater streams Stratified drift Mined for gravel