CHAPTER 5 HONORS EARTH SCIENCE GLACIERS CHAPTER 5 HONORS EARTH SCIENCE

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

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

Trans Labrador Highway

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.gif http://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 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’’

Kelly’s Island Glacial grooves

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.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 4478 m 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

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

Erratics along Lake Michigan Shoreline

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 MADE OF TILL Deposited along edge of glacier during melting

MORAINES Terminal- very end of glacier Lateral- side of glacier Recessional- progresses behind terminal

terminal moraine –

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

Drumlin Formation

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

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

What glacial landform are the arrows pointing to?

Why do scientists believe that glaciers once covered Michigan?

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

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.

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

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 them – widening and deepening them to form today’s lake bottoms.

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

Kettle Lakes

Mt. Holly

Boyne Mountain

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

http://homepage.tinet.ie/~jconsidi/BWS/karst4.jpg

Isostatic rebound The land is rebounding once the weight of the glacier left 3 cm/year

Isostatic rebound Pictured Rocks

Glacial polish

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 Glacial polish

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