How do Glaciers affect the land?WED V17

What is a glacier?

0A large, long-lasting mass of ice which forms on land and moves downslope because of gravity.

What metaphors do we use for glaciers?

0Glaciers are often referred to as a River of Ice or0Bulldozer of Ice

http://upload.wikimedia.org/wikipedia/commons/1/1e/CAT-D10N-pic001.jpg

How do glaciers form?

http://library.thinkquest.org/3876/images/howgla.gif

How do glaciers form?

Glaciers form over many years in places where the snowfall in winter exceeds the snow melt in summer

Gravity pulls the ice down the hill

http://www.swisseduc.ch/glaciers/earth_icy_planet/icons-11/20.jpg

What are the two types of glaciers?

Alpine and Continental

Alpine Glaciers

0A.k.a. Valley Glaciers

0 form near mountain tops and slide down the valleys

0They can be hundreds of feet thick.

Tyndall Glacier, Alaska

Aletsch Glacier, Switzerland 115 sq miles

http://travelguide.all-about-switzerland.info/pictures-famous-swiss-glaciers.html

Continental Glaciers

Continental Glaciers

0 cover large areas (Antarctica, Canada)

0 can be 2 – 3 miles thick

0Weight of the ice depresses the ground

0When these glaciers melt the land ‘rebounds’

0Some areas depressed during the last ice age are still rising

http://www.prolitegear.com/prolitegear/images/large/antarctica_02_lg.jpg

http://exposedplanet.com/images/antarctica-group-sled-vinsonbc-camp1.jpg

http://exposedplanet.com/images/mountain-rangefrom-ph-antarctica.jpg

What are the Landscape Features of Glaciated Areas?

What are the landscape features left by Alpine or mountain

glaciers?0Till- direct deposit of glacier; unsorted sediment0Mountain shape: 0Rugged landscapes 0Jagged peaks

0U-shaped valley0Moraine- a mass of till

Rugged LandscapesJagged Peaks

Northeast-looking oblique aerial photograph showing the snow-covered summit accumulation area of Mount Fairweather, Fairweather Range,

Glacier Bay National Park, Alaska.

Materhorn

http://www.kuleuven.ac.be/geologie/geo-algemeen.html

West-looking photograph showing an angular arete ridge, composed of schist, on the upper Taku Glacier, Juneau Icefield, Tongass National

Forest, Coast Mountains, Alaska.

U-Shaped Valley

http://www.nps.gov/history/history/online_books/brochures/1936/glac/images/fig13c.jpg

River Valley Glacial Valley

Moraine

0Mass of till (unsorted sediment) left by a glacier

http://www.yosemite.ca.us/library/geologic_story_of_yosemite/images/62.jpg

The u-shaped valley to the right side of the photo is the ice-free valley of Talkeetna Glacier, Talkeetna Mountains, Alaska. Note cirque at the top of

the valley on the left.

Aletsch Glacier, Switzerland

http://travelguide.all-about-switzerland.info/pictures-famous-swiss-glaciers.html

Ground Moraine

Terminal Moraine

Mendenhall Glacier, Tongas National Park

What are the characteristics left by Continental Glaciers?0Valleys- u shaped

0Till - unsorted sediment0Kettle lakes0Scratches and grooves0Drumlins

Kettle Lake

http://www.scienceclarified.com/images/uesc_06_img0334.jpg

http://dnr.metrokc.gov/wlr/waterres/smlakes/LakeStewWeb25/GeoDrawing.JPG

Finger Lakes

0streams and lakes were modified by glaciers

0Retreating glaciers deposited recessional moraines that blocked the water flow and created deep lakes

0Examples0 Seneca lake: 40 miles long, 618 feet deep0 Cayuga: 40 miles long, 435 feet deep

http://upload.wikimedia.org/wikipedia/commons/5/5f/Fingerlakesmap.png

NASA photo

Striations (Scratches)

http://images.google.com/imgres?imgurl=http://education.usgs.gov/schoolyard/IMAGES/GlacialStriations2.jpg&imgrefurl=http://education.usgs.gov/schoolyard/CoolGeologyActivity.html&h=297&w=447&sz=45&hl=en&start=1&tbnid=y1qmEFaxgJ64ZM:&tbnh=84&tbnw=127&prev=/images%3Fq%3Dglacial%2Bstriations%26gbv%3D2%26svnum%3D10%26hl%3Den

Grooves

Polished Rock

http://3dparks.wr.usgs.gov/nyc/images/fig21.jpg

Drumlin

http://oz.plymouth.edu/~sci_ed/Turski/Courses/Earth_Science/Images/4.drumlin.jpg

http://geoscape.nrcan.gc.ca/calgary/geotour/6_e.php

A SWARM OF DRUMLINS

http://www.drumlinarealandtrust.org/images/drumlins.jpg

IcebergsForm when chunks of ice ‘calve’ off the front of the glacier and land

in the water

http://images.google.com/imgres?imgurl=http://www.atacamaphoto.com/antarctica/antarctica22.jpg&imgrefurl=http://www.atacamaphoto.com/antarctica/antarctica22.htm&h=408&w=608&sz=101&hl=en&start=37&tbnid=raJxaBCeP2TyMM:&tbnh=91&tbnw=136&prev=/images%3Fq%3Dantarctica%26start%3D20%26gbv%3D2%26ndsp%3D20%26hl%3Den%26sa%3DN

Iceberg in Antarctica

Floating Icebergs

A Zodiak is cruising along a glacier front, showing the tremendous size of the ice blocks

Giant Iceberg

Gentoo penguin family, Antarctica

What are the tell-tale signs that a glacier was in the area?0________________ valley0________________ sediment0________________ in bedrock

See you in class!