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
well-sorted sediment deposited by glacial meltwater.
Stratified drift
a large boulder deposited by a glacier far from the bedrock from which it originated
Glacial erratic
a mound of till deposited by a glacier.
Moraine
a plain of debris deposited by meltwater from an ice-sheet.
Outwash plain
a streamlined hill formed from glacial deposits
Drumlin
a hill of stratified glacial deposits, formed by sediments collecting in water on top of or adjacent to a melting glacier.
Kame
a lake filling a depression in the land surface that formed by the melting of buried blocks of ice.
Kettle lake
a ridge of sand and gravel, formed from a stream flowing beneath a glacier.
Esker
the vast quantities of water tied up in glacial ice can lower sea level.
Sea level change cause of glaciation
the weight of thick ice sheets during the Pleistocene caused the crust to sag. The ice sheets melted and the weight was removed the crust began to “bounce back”. Features associated with this term are raised beaches.
Glacial rebound cause of glaciation
