© K. Coder 2015

  Erosion & Deposition By:

Glaciers

Guided Notes

Surface Processes

© K. Coder 2015

26) How does moving ice erode and deposit sediments?

• Glaciers (Movement of Ice): a naturally formed mass of ice and snow that moves downhill on land under the influence of gravity

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28) How do glaciers move?• Glaciers will advance (move forward) when

there is more snow accumulating than melting.

• Glacier will retreat (move backward) when there is more melting than snow accumulating.

29) What evidence do we have of glacial erosion?

a) Striations: parallel scratches on bedrock

• Formed when rocks that are transported on the bottom of the glacier leaves scratches and grooves in the bedrock over which they pass.

• Indicate the direction the glacier moved.

29) What evidence do we have of glacial erosion?

b) U-shaped Valley: when a glacier moves down a mountain valley, the glacier and its load of sediment pluck, scrape, and scour the sides of the valley changing its profile to a broader U-shape.

30) What landscape features are evidence that glaciers deposited sediments?

a) Till: unsorted, unlayered glacial sediments that are deposited directly by a glacier.

© K. Coder 2015

30) What landscape features are evidence that glaciers deposited sediments?

b) Moraine: a hill of till deposited directly from an edge or bottom of a glacier

An exposed area of the Harbor Hill Moraine (Long Island, NY)

30) What landscape features are evidence that glaciers deposited sediments?

c) Outwash plain: horizontal sorted layers of glacial material in front of the glacier, formed by the meltwater of the glacier

Moraine

Outwash plain

30) What landscape features are evidence that glaciers deposited sediments?

d) Drumlin: glacial hills of unsorted, unlayered sediment that are shaped like the back of a spoon by the ice • Indicates the direction of glacial movement (toward the

gentle slope).

Glacier movement

© K. Coder 2015

30) What landscape features are evidence that glaciers deposited sediments?

e) Kettle lake: when blocks of ice are left behind, form a depression, and melt.

• If they the meltwater hits the water table, a lake will form.

• Example in NY: Lake Ronkonkoma (Long Island)

30) What landscape features are evidence that glaciers deposited sediments?

f) Erratic: rocks that have been transported to an area (type of rock not normally found in that area)

• Example in NY: Many glacial erratic found in Central Park

Central Park, NYC Glacial Erratic

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30) What landscape features are evidence that glaciers deposited sediments?

g) Glacial Lakes 1. New York State Finger Lakes: • Lakes that fill in long, deep, U-shaped valleys. • Indicate direction of glacier movement (in a north-south position).

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

1. The elongated hills labeled R are most useful in determining the (1) age of the glacier (2) direction the glacier has moved (3) thickness of the glacier (4) rate at which the glacier is melting

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

2. Which feature will most likely form when the partially buried ice block melts? (1) drumlin (3) kettle lake (2) moraine (4) finger lake

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

3. The ridge of sediments from X to Y can best be described as (1) sorted and deposited by ice (3) unsorted and deposited by ice (2) sorted and deposited by meltwater (4) unsorted and deposited by meltwater

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

4. Describe one difference between the arrangement of sediment in the moraines and the arrangement of sediment in the outwash plain.

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

5. Describe one piece of evidence likely to be found on the exposed bedrock surfaces that could indicate the direction this glacier moved.

© K. Coder 2015

✓ Review – Glaciers The diagram below shows the edge of a continental glacier that is receding. R indicates elongated hills. The ridge of sediments from X to Y represents a landscape feature.

6. The diagram below shows a partial cross section of a valley. On this diagram, draw a line beginning at X and ending at Y to show the shape of this valley after it was eroded by glacial ice that flowed down the valley.