Unit 2

Question 1

What is an Ice Sheet?

Answer 1

Completely submerged rock/land, forming a gently sloping dome of ice.

• Several Km thick
• 50,000km^2 in size
• Unconstrained

eg Greenland ice sheet

Question 2

What is an ice cap?

Answer 2

Smaller version of ice sheet. Occupies upland areas.

• Smaller than 50,000km^2
• Unconstrained

eg Devon Ice Cap (Canada)

Question 3

What is an Ice field?

Answer 3

Ice covering an upland area, but not thick enough to bury topography.

• 10-10,000km^2
• Constrained

eg Colombia Ice field (Canada)

Question 4

What is an ‘Unconstrained ice mass’?

Answer 4

These masses have a morphology and flow pattern that is the most part independent of underlying topography.

Question 5

What is a ‘Constrained ice mass’?

Answer 5

These masses have a morphology and flow pattern that is strongly dependent on underlying topography.

Question 6

What is ‘topography’

Answer 6

Natural shape of the land.

Question 7

What is morphology?

Answer 7

The form, shape, structure of an ice mass.

Question 8

What is a Valley glacier?

Answer 8

A glacier confined between valley walls and terminating in a narrow tongue.
• Forms ice caps, sheets or cirques.
• May terminate in sea as a tidewater glacier

• 3-1,500km^2
• Constrained

eg The Alps

Question 9

What is a Piedmont glacier?

Answer 9

A valley glacier that extends beyond the end of a mountain valley into a flatter area and spreads out as a fan.

• 3-1000km^2
• Constrained

eg Malaspina Glacier, USA

Question 10

What is a Cirque glacier

Answer 10

Smaller glacier occupying a hollow on the mountain side - carving out a cirque

• 0.5-8km^2
• Constrained

eg Lower Curtis Glacier

Question 11

What is an Ice shelf?

Answer 11

Large area of floating glacier ice from the coast where several glaciers have reached the sea and coalesce.

• 10-100,000km^2
• Constrained

eg Ward Hunt (Canada)

Question 12

What is thermal regime?

Answer 12

Temperature of ice.

Question 13

What is a Cold Based (polar) Glacier?

Answer 13

• Found at high LATITUDES
• Average ice temp. is well below 0°C
• May be up to 500m thick
• Glacier is permanently frozen to bedrock

Question 14

What is a Warm Based (temperate) Glacier?

Answer 14

• Found at high ALTITUDE areas
• Temp. fluctuates above and below melting point (seasonal)
• Water exists as a liquid below 0°C due to pressure
• Not permanently frozen to bedrock

Question 15

What is pressure melting?

Answer 15

Pressure melting is where ice will melt at temperatures below 0°C due to the pressure from the weight of the overlaying glacial ice.

Warm based glaciers experience pressure melting at their base.

Question 16

What is regelation?

Answer 16

Providing pressure on ice which turns it into water.
Once this pressure is removed, it freezes and turns into ice again.

Question 17

What is basal sliding?

Answer 17

Basal Sliding occurs where there is meltwater at the base of the glacier (therefore only beneath warm based glaciers). There are 2 specific basal sliding processes: ENHANCED BASAL CREEP & REGELATION SLIP.

EBC: Ice deforming around the topography, due to rocks and boulders protruding into overlying ice.

RS: Regelation occurring.

Question 18

What is internal deformation?

Answer 18

Deformation within the glacial ice.
• Intergranular Flow
- Involves the displacement of ice grains relative to each other
• Laminar Flow
- Involves the layers of ice within the glacier slipping over each other

Question 19

What are Glacial Surges?

Answer 19

Surges are periods of rapid movement when a glacier snout advances up to 1000x faster than normal.