4.2: Present and Past distribution of Ice Cover

Question 1

Define the Cryosphere

Name its features

Answer 1

The parts of the Earth crust and atmosphere subject to temperatures below 0 degrees for at least part of the year

It consists of ice sheets, glaciers, sea ice, lake ice, ground ice (permafrost) and snow cover.

Question 2

1. Define what an Ice Sheet is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 2

1. Complete submergence of topography; form a gently sloping dome of ice several kilometres thick in the centre
2. 10 - 100,000 sq Km
3. Unconstrained
4. Antarctica

Question 3

1. Define what an Ice Cap is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 3

1. Smaller version of an ice sheet occupying upland areas; outlet glaciers and ice sheets drain both ice sheets and ice caps
2. 3 - 10,000 sq Km
3. Unconstrained
4. VatnaJokull (Iceland)

Question 4

1. Define what an Ice Field is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 4

1. Ice covering an upland area but not thick enough to bury topography
2. 10 - 10,000 sq Km
3. Unconstrained
4. Patagonia (Chile)

Question 5

1. Define what a Valley Glacier is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 5

1. Glacier confined between valley walls and terminating in a narrow tongue; forms from ice caps and ice/sheets and cirques; may terminate in sea as a tidewater glacier
2. 3 - 1500 sq Km
3. Constrained
4. Aletsch Glacier (Switzerland)

Question 6

1. Define what a Piedmont Glacier is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 6

1. Valley glacier which extends beyond the end of a mountain valley into a flatter area and spread out like a fan
2. 3 - 1500 sq Km
3. Constrained
4. Malaspina (Alaska)

Question 7

1. Define what an Cirque Glacier is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 7

1. Smaller glacier occupying a hollow on the mountainside - carves out a corrie or cirque; smaller version is a niche glacier
2. 0.5 - 8 sq Km
3. Constrained
4. Hodges Glacier Grytviken (south Georgia)

Question 8

1. Define what an Ice Shelf is
2. its size
3. whether it is constrained or unconstrained
4. name an example

Answer 8

1. Large area of floating glacier ice extending from the coast where several glaciers have reached the sea
2. 10 - 100,000
3. Unconstrained
4. Ronne and Ross Ice Shelf (Antarctica)

Question 9

Warm Based Glaciers

Where do they occur

specific example

2 features

Answer 9

1. Occur in high altitude areas outside of the polar region
2. the Alps

• The temperature of the surface fluctuates above and below melting point depending on the time of year whereas the rest of the ice extending downward to the base is close to melting point
• Because of the pressure of overlying ice, water exits as a liquid at temps below 0 causing the basal ice to melt continually
• The glacier is not frozen to its bed
• The glacier has lots of debris in its basal layers and significant sub glacial depositional features

Question 10

Cold Based Glaciers

Where do they occur

specific example

2 features

Answer 10

1. Occur in high latitudes
2. Antarctica

• As the average temp of ice is usually well below 0, as a result of extreme surface temperatures (as low as -20 to -30), the accumulation of heat from geothermal sources is not great enough to raise the base temp of the glacier to 0, despite the ice being up to 500m thick
• Relatively little surface melt in the very short and cool polar summers - little meltwater percolates downwards
• The glacier is permanently frozen to its bed, so there is no debris-rich basal layer

Question 11

Present distribution of ice cover

1. where is 85% of the worlds ice contained
2. How much of world ice cover is present in Greenland
3. Where is the remaining distributed?

Answer 11

1. Antarctica
2. 11%
3. across ice caps (e.g: Canada), highland ice fields and many smaller glaciers in high altitude areas (e.g: Andes)

Question 12

what are the 5 factors that influence distribution of ice cover?

Answer 12

1. Latitude
2. Altitude
3. Aspect
4. Relief
5. Direction of slope

Question 13

How does Latitude affect distribution of ice cover?

Answer 13

In high latitudes the sun’s rays hit the ground at a lower angle so the solar energy received has to heat a larger area

Question 14

How does Altitude affect distribution of ice cover?

Answer 14

Ice cover is Impacted by environmental lapse rate whereby temperature declines by 1 degree for every 100m

Question 15

How does Aspect affect distribution of ice cover?

Answer 15

Can determine the amount of snow falling and settling

Question 16

How does Relief affect distribution of ice cover?

Answer 16

In mountainous areas, aspect and relief can combine to affect the distribution of cirque glaciers

Question 17

How does Direction of slope affect distribution of ice cover?

Answer 17

In the northern hemisphere, north and east facing slopes are more sheltered and shadier, thus being more conducive to snow accumulation

Question 18

Past Distributions of Ice Cover

1. In the Pleistocene how many times greater was global ice cover than it is today?
2. Were the Greenland and Antarctic Ice sheets any bigger? If so by how much?
3. How thick was the Scandinavian Ice sheet? And what affect did it have?

Answer 18

1. 3 times
2. They only covered a slightly greater area than they do today
3. It grew to a thickness of 3000 - 4000 m and transformed the landscape of Europe