How do Glaciers affect the land? WED V17

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

What metaphors do we use for glaciers? 0 Glaciers are often referred to as a River of Ice or 0 Bulldozer of Ice

How do glaciers form?

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

What are the two types of glaciers? Alpine and Continental

Alpine Glaciers 0 A.k.a. Valley Glaciers 0 form near mountain tops and slide down the valleys 0 They can be hundreds of feet thick.

Tyndall Glacier, Alaska

Aletsch Glacier, Switzerland 115 sq miles

Continental Glaciers

0 cover large areas (Antarctica, Canada) 0 can be 2 – 3 miles thick

0 Weight of the ice depresses the ground 0 When these glaciers melt the land ‘rebounds’ 0 Some areas depressed during the last ice age are still rising

What are the Landscape Features of Glaciated Areas?

What are the landscape features left by Alpine or mountain glaciers? 0 Till- direct deposit of glacier; unsorted sediment 0 Mountain shape: 0 Rugged landscapes 0 Jagged peaks 0 U-shaped valley 0 Moraine- a mass of till

Rugged Landscapes Jagged Peaks

Northeast-looking oblique aerial photograph showing the snow-covered summit accumulation area of Mount Fairweather, Fairweather Range, Glacier Bay National Park, Alaska.

Materhorn

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

ges/fig13c.jpg River ValleyGlacial Valley

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

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

Ground Moraine

Terminal Moraine

Mendenhall Glacier, Tongas National Park

What are the characteristics left by Continental Glaciers? 0 Valleys- u shaped 0 Till - unsorted sediment 0 Kettle lakes 0 Scratches and grooves 0 Drumlins

Kettle Lake

Finger Lakes 0 streams and lakes were modified by glaciers 0 Retreating glaciers deposited recessional moraines that blocked the water flow and created deep lakes 0 Examples 0 Seneca lake: 40 miles long, 618 feet deep 0 Cayuga: 40 miles long, 435 feet deep

NASA photo

Striations (Scratches) n.usgs.gov/schoolyard/CoolGeologyActivity.html&h=297&w=447&sz=45&hl=en&start=1&tbnid=y1qmEFaxgJ64ZM:&tbnh=84&tbnw=12 7&prev=/images%3Fq%3Dglacial%2Bstriations%26gbv%3D2%26svnum%3D10%26hl%3Den

Grooves

Polished Rock

Drumlin

A SWARM OF DRUMLINS

Icebergs Form when chunks of ice ‘calve’ off the front of the glacier and land in the water

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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 ________________ valley 0 ________________ sediment 0 ________________ in bedrock

See you in class!