Glaciers Glaciation Glaciers Glacier a large longlasting mass

Glaciers & Glaciation

Glaciers • Glacier: a large, long-lasting mass of ice, formed on land that moves under the influence of gravity and its own weight • Glaciers form by accumulation and compaction of snow – Packed snow becomes firm – Then refreezes to ice

Glaciation Types • Alpine glaciation: found in mountainous regions • Continental glaciation: exists where a large part of a continent is covered by glacial ice Cover vast areas

Two types of glaciers Alpine Glaciers Continental Glaciers

Features of Alpine Glaciation

Horn A steep-sided, pyramidshaped peak produced by headward erosion of several cirques. Arete A sharp, jagged, knife-edge ridge between two cirques or glaciated valleys.

Cirques Glacial Valley Horn Arete

Hanging Valley A glacial trough of a tributary glacier elevated above the main trough.

a lake in a cirque Tarns

Glacier Braided Stream A plain formed by a blanket-like deposition of glacial outwash. Outwash Plain

U-shaped Valleys

Glacial Sediments Glacial Till __________ Unsorted and unstratified sediments that collect directly from the melting of ice. Unstratified sheets of clayey silt that are transported beyond the margins of a glacier by wind and/or braided streams ___________ Loess

Moraines are large piles of rocks composed of Unsorted Till (glacial debris) Unsorted Till

Lateral Moraines Medial Moraines

Drumlins Ice Flow

Kettles A round lake in a depression in glacial drift. . . formed by melting of an isolated block of ice.

Kame A steep-sided mound of stratified drift. . . that formed in contact with glacial ice.

Erratic A boulder that was carried far from its source by a glacier.

Esker A long, narrow, sinuous ridge of stratified drift. . . deposited by meltwater streams flowing beneath the glacier.