Glacial Systems

Question 1

ablation

Answer 1

The loss of ice or snow from a glacier. This can occur by melting, by evaporation, and by icebergs breaking off of a glacier if the glacier borders a sea or lake.

Question 2

ablation zone

Answer 2

The lower area of a glacier where the rate of ablation is higher than the rate of accumulation.

Question 3

accumulation

Answer 3

The gain of snow and ice in a glacier. This is usually from precipitation in the form of snow, but also includes snow blown onto the glacier from surrounding slopes.

Question 4

accumulation zone

Answer 4

The upper area of a glacier where the rate of accumulation is higher than the rate of ablation.

Question 5

advance (of a glacier)

Answer 5

Occurs over a time period when accumulation averaged across the whole glacier exceeds ablation averaged across the whole glacier. The glacier becomes larger and extends further.

Question 6

calving

Answer 6

Where glaciers reach the sea or a lake, it is the process by which pieces of the glacier break off and float away.

Question 7

crevasses

Answer 7

Fractures (or breaks) that can be seen at the surface of the glacier caused by stretching (extending) of the ice.

Question 8

equilibrium line

Answer 8

The boundary between a glacier’s accumulation zone and its ablation zone. Along this boundary, averaged over the year, accumulation is equal to the amount of ablation.

Question 9

glacier ice

Answer 9

Ice formed from snow which has been compacted by the weight of snow being added above it. The pressure forces the glacier ice to move downslope.

Question 10

glacier terminus

Answer 10

The downward end of the glacier.

Question 11

mass balance

Answer 11

The relation between accumulation and ablation for a glacier (also called ‘glacier budget’). It is positive if over a year there is more accumulation than ablation. It is negative if there is more ablation than accumulation.

Question 12

moraine

Answer 12

Accumulations of rock debris being transported or deposited by a glacier. This term also refers to the landforms made of the debris after it has been deposited by the glacier.

Question 13

retreat (of a glacier)

Answer 13

Occurs over a time period when ablation averaged across the whole glacier exceeds accumulation averaged across the whole glacier. The glacier becomes smaller and the end of the glacier goes back.

Question 14

snout

Answer 14

The lower part of a valley glacier’s ablation zone.