Glaciers and Glaciation Flashcards
The formation of glaciers requires both ___ and sufficient ___ for ice to accumulate to a sufficient thickness for it to flow.
Cold temperatures; Moisture
Snow falls and becomes compacted, forming a granular ice called ___.
Firn
When the thickness reaches ___ meters the pressure becomes great enough for the firn to be transformed to glacial ice, which can begin to flow.
50
___ is the balance between the accumulation of snow and ice at one end of a glacier and the melting and evaporation of ice at the other end.
Glacial budget
The dividing line between those areas where there is a net gain of ice and where there is a net loss is called the ___.
Snow line
The area above the snow line is called the zone of
___; the area below the snow line is called the zone of ___
accumulation; wastage
The ice deforms and flows like putty under the force of gravity
Plastic flow
The ice mass slides on a film of water at its base.
Basal slip
Rapid movement of glaciers (called ___) is usually attributable to basal slip.
Surges
a glacier that formed at a high altitude and flows in a mountain valley
Alpine Glacier
a broad, thick expanse of glacial ice covering land in a cold climate.
Continental Ice Sheet
Glacial ice often includes sand, gravel, and boulders, which can gouge bedrock to form ___ or abrade the bedrock to give it a ___.
Glacial striations; glacial polish
Rock and sediment are picked up by the ice and absorbed into the glacial by a process called ___.
Plucking
A major feature of landscapes that have been eroded by glaciers is that V-shaped stream valleys become converted to ___ glacial valleys.
U-shaped
a U-shaped mountain valley that has been widened and deepened by a glacier.
Glacial trough
a valley entering a glacial trough whose floor is high above the trough’s floor.
Hanging valley
a narrow ridge separating two glacial valleys.
Are^te
a sharp mountain peak sculpted by 3 or more adjoining cirques.
Horn
an amphitheater-shaped basin at the head of a glacial valley.
Cirque
a small lake in a cirque
Tarn
a chain of small lakes in a glacial trough.
Pater noster lakes
a glacial trough that has been flooded by sea level rise and is now a deep steep-sided bay
Fjord
general term for all glacial sediments.
Glacial drift
unsorted sediment left behind by the melting of a glacier.
Glacial till
