Glaciers

How are

Glaciers and Long Island

related?

Glaciers

Snowfall exceeds melting.

High altitudes and polar regions.

Gravity moves mass downhill.

Firn = very dense snow layer.

Continental Glaciers

Ice sheets that cover continents.

Kilometers thick.

Only 2 exist:

- Greenland and Antarctica

Valley Glaciers

Begins in a cirque = bowl-shaped basin at mountaintop.

Crevasses = cracks in the glacier.

Erosion

U-shaped Valleys

Cirques, Aretes and Horns.

Hanging Valleys - from tributary

Erosion

Striations = parallel scratches on bedrock... from rocks on bottom of glacier

Polish = fine material rubs rock smooth.

Striations

Polish

DepositionMoraines - Unsorted pile of debris = till

Erratics = large isolated boulders.

Drumlins = long, low mounds of till with teardrop shape.

Outwash Plain (sorted) = sediments that are “washed out” in front of glacier.

Erratic

Central Park, NYC

Drumlin

Lakes

Kettle Formation:

Kettle Lakes

Glacial LakeForms when ice dams a stream.

Ice Age Glacier Limit