Glaciers & Glaciation

Glaciers

• Glacier: a large, long-lasting mass of ice, formed on Glacier: a large, long-lasting mass of ice, formed on land that moves under the influence of gravity and land that moves under the influence of gravity and its own weight its own weight

• Glaciers form by accumulation and compaction of Glaciers form by accumulation and compaction of snowsnow– Packed snow becomes Packed snow becomes firm– Then refreezes to iceThen refreezes to ice

Glaciation Types

• Alpine glaciation: found in mountainous Alpine glaciation: found in mountainous regions regions

• Continental glaciation: exists where a Continental glaciation: exists where a large part of a continent is covered by large part of a continent is covered by glacial iceglacial iceCover vast areas

Continental GlaciersAlpine Glaciers

Two types of glaciers

Features of Alpine Glaciation

Horn Arete

A steep-sided, pyramid-shaped peak produced

by headward erosion ofseveral cirques.

A sharp, jagged, knife-edge ridge

between two cirques or glaciated valleys.

Cirques Glacial Valley

Horn

Arete

A glacial trough of a tributary glacierelevated above the main trough.

Hanging Valley

Tarns

a lake in a cirque

Outwash

Plain

Braided Stream

Glacier

A plain formed by a blanket-likedeposition of glacial outwash.

U-shaped Valleys

GlacialTill

Loess

GlacialSediments ___________________

Unsorted and unstratified sediments

that collect directlyfrom the melting of ice.

Unstratified sheets ofclayey silt that are

transported beyond themargins of a glacier by

wind and/or braided streams______________________

Moraines

Unsorted Till

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

Medial Moraines

Lateral Moraines

Drumlins

IceFlow

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.