Earth Science

7.1 Glaciers

Ice Age

A period of time when much of Earth’s land is covered by glaciers

Glaciers

A thick mass of ice origination on land from the compaction and recrystallization of from snow that slows evidence of past or present flow

Snowline

Lowest elevation in a particular area that remains covered in snow all year

Valley Glaciers

A glacier confined to a mountain valley, which in most instances had previously been a stream valley; also known as an alpine glacier

Ice Sheet

Are enormous ice masses that flow in all directions from one or more centers and covered everything but the highest land

Glacial trough

The once narrow V-shaped valley is changed into U-shaped

Till

Sediment of different sizes deposited directly by glacier

Stratified drift

Is sediment laid down by glacial meltwater

Moraine

A ridge of unsorted sediment left by a glacier

Key Concepts

What types of glaciers exist, and where is each type found?Valley GlaciersIce Sheets

How do glaciers move?Plastic FlowBasal Slip

What distinguishes the various types of glacial drift? Weight of overlying ice and the associated

pressureWhat landscape features do glaciers

form?Glaciated ValleysCirquesAretes and Horns