Post on 26-Mar-2015
transcript
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