GLACIERS CHAPTER 11 GEOLOGY

Top 10 glacier facts 10. Approximately 10 percent of the Earth is covered by glaciers; during the last Ice Age, they covered one-third of the Earth’s surface. 9. Glacier ice is the largest reservoir of fresh water on the planet, storing an estimated 75 percent of the world’s supply. 8. Glaciers are found in 47 countries. 7. A glacier can range in length from the equivalent of a football field to more than 100 miles. 6. The Antarctic ice sheet is actually a glacier and has existed for at least 40 million years. If it were to melt in its entirety, sea levels would rise 210 feet worldwide, according to the U.S. Geological Service.

5. Though it sits on the equator, Mount Kilimanjaro is glaciated. 4. On steep slopes, a glacier can be as thin as 50 feet. 3. Mountain valleys are typically “V” shaped before being taken oven by a glacier; during glaciation, the valley widens and deepens and thus becomes “U” shaped. 2. A single glacier ice crystal can grow to be as large as a baseball. 1. Alaska is estimated to have more than 100,000 glaciers. Most remain unnamed

World glaciers

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

Glaciar Perito Moreno, in Santa Cruz province, Argentina 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

Trans Labrador Highway

Snow to firn to glacial ice

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

Kelly’s Island Glacial grooves

Glacial polish

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.

http://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

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

Horn A tall, pointed rock peak left at the top of a mountain 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 1500 feet above sea level.

Arete – spines or ridges of rock that separate glacial valleys

U-shaped Valley - Yosemite National Park

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

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

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

till outwash

Erratics Boulders carried great distance by the glacier Don’t match surrounding rock “strange rock”

Erratics along Lake Michigan Shoreline

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.

MORAINES Deposited along edge of glacier during melting Ridges of till Terminal- very end of glacier Lateral- side of glacier Recessional- progresses behind terminal

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

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

Ground Moraine- flat till deposits between recessional moraines

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.

Drumlins Hills of sediment deposited by the glacier- till

Boyne, Nubs Nob, Irish Hills are drumlins in MI

MI Drumlins

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

Mt. Holly is a kame

ESKERS Meandering ridges of stratified drift Deposited by meltwater streams Mined for gravel

Mt. Brighton Mason esker

Kettle Lakes Made from ice blocks Deep inland lakes rocky

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.

Outwash plain From melt water (lake) in front of ice Flat; sandy Contains outwash and often kettle lakes

Pleistocene Epoch “Ice Age” 2my- present

1.5 mya

mastodon

Mammoth Bigger than mastodon Curvy tusk

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

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

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

Why do scientists believe that glaciers once covered Michigan?

Moraine Deposits =unsorted sediments What can deposit unsorted sediment? Mass movement? ice

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.

3 ice lobes

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

The Glacial History of Michigan The depth of the lake is determined by the thickness of the ice at the time of glaciation. The farther north the lobe of ice, the thicker it was. Consequently, the lakes get more shallow in the southern Great Lakes region. LAKE: GREATEST DEPTH: Superior = 1,333 ft. Michigan = 925 ft. Huron = 725 ft. Ontario = 283 ft. Erie = 212 ft.

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

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

Isostatic (crustal) rebound land is rebounding up from weight of glacier about 53 cm/ century

Pictured Rocks

Kettle Lakes

Why do scientists believe that glaciers once covered Michigan? Michigan is covered with till The moraine deposits follow the outline of Great Lakes Erratics Striations Isostatic rebound

What glacier evidence do we see in Grosse Pointe? Erratics Old beach ridges Ridge road Mack avenue Till

Resources http://cse.cosm.sc.edu/erth_sci/Erosion/plucking.jpg http://www.skidmore.edu/academics/geo/courses/ge101/Pictures/Glaciers/GlacialStriations.jpg http://www.go2moon.com/image/Valdez-Glacier.jpg http://www.glaciers.pdx.edu/kennicott/photos99/glacier.jpg http://www.brownbearsw.com/photos/pws/moraine.jpg http://www.homepage.montana.edu/~geol445/hyperglac/depproc1/moraine.JPG http://www.ucalgary.ca/~dgsmit/MORAINE.jpg http://mac01.eps.pitt.edu/harbbook/c_viii/images/icefields/Hwb0530.GIF http://www.geographyhigh.connectfree.co.uk/s3glacgeoghigh34b.gif http://www.uwsp.edu/geo/faculty/lemke/images/lithosphere/drumlin_diagram_small.gif http://online.sd43.bc.ca/della/images/drumlin.jpg http://www.geology.wisc.edu/~qlab/g420/drumlin.jpg http://www.bbc.co.uk/scotland/education/bitesize/standard/img/geography/glaciation/g98.gif http://pbisotopes.ess.sunysb.edu/esp/Science_Walks/carmans/kettle-hole.gif

http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images3/southern_Kettle_Moraine_lakes_WI_800.jpg http://images3.vrbo.com/vrbo/images/18982c.jpg http://www.on.ec.gc.ca/greatlakeskids/images/g_lakes_form.gif http://wrgis.wr.usgs.gov/docs/parks/glacier/UvalleyB.gif http://wrgis.wr.usgs.gov/docs/parks/glacier/UvalleyC.gif http://www.jchl.co.uk/photos/greenland/Valley.jpg http://www.emporia.edu/earthsci/student/martel1/ice.jpg http://wrgis.wr.usgs.gov/docs/parks/glacier/gifJPGdisplay.html http://www.uwsp.edu/geo/faculty/lemke/alpine_glacial_glossary/images/more_examples/canada_cirque01_dh.jpg http://www.uoregon.edu/~millerm/Kluane1.jpeg http://people.surfaceeffect.com/pete/photos/folksholiday/yosemitevalley/valley2.jpg http://www.theotherpages.org/images/image200.jpg http://www.northforkmedia.com/spiveyscience/images/glacialerosion/pages/grinnellcirqueareteetc_jpg.htm http://www3.uakron.edu/modlang/97trip/d16f.jpg http://tvl1.geo.uc.edu/ice/Image/icland/Greenland.html http://www.bougerolle.net/photos/matterhorn.jpg

http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images3/glacial_erratics_Lake_Michigan_WI_800.jpg http://www.fettes.com/Cairngorms/images/Easter_Island.jpg http://rt23.com/Scenery/spring/images/tripod_rock.jpg http://ic.ucsc.edu/~rocks/eart109/Photo_Composition/Top_Pothole.jpg http://perth.uwlax.edu/faculty/stoelting/Intro/Guides/Images3/southern_Kettle_Moraine_lakes_WI_800.jpg