Glaciers Flashcards
What is the zone of ablation in a glacier?
This is below the snowline. It is the zone where melting occurs.
What is the zone of accumulation?
This is above the snowline. It is where snowfall occurs.
What is the snowline?
This is the boundary between the accumulation zone and the zone of ablation. It is in the middle.
What happens when ablation exceeds accumulation?
The glacier retreats.
What happens when accumulation exceeds ablation?
The glacier advances.
How does a glacier form?
It starts as snow which is compacted into firn and then ice. As ice develops, its mass forces it to move downhill.
Iceberg
A piece of ice that breaks off of a ice sheet into water.
Ice sheet
A large ice mass that covers a smaller landmass.
Ice shelf
A floating piece of ice attached to the landmass.
How does a glacier move?
It moves using basal slip and internal plastic flow.
What is basal slip?
A thin layer of water develops under the ice sheet due to pressure, melting, geothermal heat, and thermal regime. The ice sheet then moves on the water.
What is internal plastic flow?
Top particles move faster than bottom particles because they “piggyback” on the below particles and there is less friction.
What are the depositional features of a glacier?
Drumlin, erratic, presumpscot formation, end morraine, till, kame, esker, and kettle lake.
What are the erosional features of a glacier?
striations,u-shaped valleys, hanging valleys, Roche moutonnees, cirques, tarns, paternosters, horns, and aretes.
What is a drumlin?
A drumlin is an a-symmetrical hill with a sloping side and a steep side. The steep side is where the glacier came in from.
