Chapter Review Assess your understanding of concepts related to this chapter by answering the questions below. Click the question to reveal the correct answer.
Glaciation occurs where the winter-time accumulation of snow exceeds the summer loss. Through time, snow accumulates to a sufficient depth to metamorphose into ice. Conditions for glaciation usually occur at high latitudes or high altitudes where temperatures are cool enough to inhibit melting.
If the mass balance is positive the glacier will
advance. If the mass balance is
negative it will retreat.
Glaciers move when the weight of ice causes the ice to deform and bulge outwards from the zone of accumulation and bby basal slip, the sliding of ice over the surface on a film of meltwater.
Crushing, plucking and abrasion.
Till is an unsorted mixture of material deposited by ice. Stratified drift is sorted material deposited by melt water.
Striations and grooves are oriented in the direction
of flow, while chatter marks are perpendicular to flow.
A moraine is an accumulation of till producing irregular topography and often taking the form of a belt of low hills. A terminal moraine marks the furthest advance of a glacier. A recessional moraine forms when the glacier recedes and stagnates for a period of time. Ground moraine is an irregular deposit of till spread over the surface beneath the ice.
Kettles are depressions left by melting ice blocks surrounded by till or stratified drift. Kames are steep-sided hills built by the deposition of stratified drift laid down in or around ice.
The "tail" of the drumlin points in the direction of movement.
Eskers form by the deposition of glacial drift,
composed mostly of glacio-fluvial gravel in a subglacial stream
during ice stagnation.
Cirques are bowl-shaped depressions scoured into the side of a mountain by an alpine glacier. Tarns are small depressions filled with water on the cirque floor.
A hanging valley is a tributary valley left hanging at a high elevation above the main valley glacier floor.
A horn is a pyramidal peak formed by the headward erosion of cirque glaciers. Arêtes are serrated ridges formed by the erosion of an interfluve by valley glaciers.
Stream valleys are V-shaped while glaciated valleys
are U-shaped.
Staircase lakes form when mountain valley streams are blocked by and fill depressions behind rock steps or moraines.
Medial moraines form by the merger of lateral moraines.
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