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
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.