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Glaciated Landscapes > Unit 2 Notes > Flashcards

Unit 2 Notes Flashcards

1
Q

What is the Crysosphere?

A

The parts of the earth’s crust and atmosphere that are below 0 degrees for at least part of each year.

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2
Q

What parts of a glaciers does climate control?

A

The annual temperature cycle of a region, the amount of precipitation that falls as snow.

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3
Q

How does topography control a glacier?

A

Provides the land surface for a glacier, and dimensions.

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4
Q

What is an unconstrained ice mass?

A

Ice masses which have a morphology and flow pattern which is independent of underlying topography.

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5
Q

What is a constrained ice mass?

A

Ice masses which have a morphology which is dependent on underlying topography

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6
Q

What is an ice sheet?

A

An ice mass of complete submergence of regional topography. Over 50,000 km.

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7
Q

Are ice sheets constrained on unconstrained?

A

Unconstrained. e.g. Greenland, Antarctica.

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8
Q

What is an ice cap?

A

Occupies upland areas, a smaller version of an ice sheet. Smaller than 50,000 km.

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9
Q

Are ice caps constrained or unconstrained?

A

Unconstrained. e.g. Jostedal glacier, Norway.

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10
Q

What is an ice field?

A

Ice covering an upland area, not thick enough to bury underlying topography. 10 - 10,000 km.

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11
Q

Are ice fields constrained or unconstrained?

A

Constrained. e.g. Columbia glacier, Canada.

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12
Q

What is a valley glacier?

A

A glacier confined between valley walls, terminating in a narrow tongue. 3 - 1500 km.

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13
Q

Are valley glaciers constrained or unconstrained?

A

Constrained.

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14
Q

What is a piedmont glacier?

A

Valley glacier that extends beyond the end of a mountain valley into a flatter area. 3 - 1000 km.

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15
Q

Are piedmont glaciers constrained or unconstrained?

A

Constrained.

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16
Q

What are cirque glaciers?

A

Smaller glaciers occupying a hollow on the mountain side carving as a corrie or cirque. 0.5 - 8km.

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17
Q

Are cirque glaciers constrained or unconstrained?

A

Constrained.

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18
Q

What is an ice shelf?

A

A large area of floating glacier ice extending from the coast, where several glaciers have reached the sea. 10 - 100,000 km.

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19
Q

Are ice shelves constrained or unconstrained?

A

Unconstrained.

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20
Q

How does thermal regime affect glacial movement?

A

Creates two different types of glaciers.

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21
Q

What are the characteristics of cold based glaciers?

A

High latitude locations, Average ice temperature well below 0 degrees, Glaciers up to 500m thick, Permanently frozen to bedrock.

22
Q

What are the characteristics of warm based glaciers?

A

Found outside of polar regions, Temperature fluctuates above and below melting point, increased pressure of overlying ice.

23
Q

What is the pressure melting point?

A

The temperature below 0 degrees at which ice can melt due to pressure of glacial ice.

24
Q

What is the normal melting point of ice?

A

0 degrees.

25
Q

What is the rate of pressure melting?

A

1 degree for every 100kg/cm of pressure.

26
Q

Why is there more meltwater at the base of a warm based glacier?

A

There isn’t enough pressure to melt cold based glaciers.

27
Q

What happens when warm based glaciers move over weak rock?

A

The sediment can deform under the weight of the glacier, which moves ice on top of it.

28
Q

How much does glacial movement vary per year?

A

3 - 300 metres per year.

29
Q

What experiment is done to show regelation?

A

Putting a wire through ice, staying solid. Ice will melt beneath, and ice stays solid because ice compresses itself, and turns into water, then re-solidifies when pressure is taken off.

30
Q

What is Basal sliding?

A

Occurs when there is meltwater at the base of a glacier, can only occur beneath warm based glaciers.

31
Q

How does basal sliding allow movement to occur?

A

Meltwater acts as a lubricant, and reduces friction between the base of the glacier, and underlying bedrock.

32
Q

What are the two types of basal sliding?

A

Enhanced basal creep, regelation slip.

33
Q

What is enhanced basal creep?

A

Bedrock is rarely smooth, and rocks and boulders go above into the overlying ice- Ice deforms when it comes into contact with obstacles, but doesn’t reach the point of melting pressure.

34
Q

What is regelation slip?

A

When the temp of basal ice is close to the pressure melting point, so pressure on the up glacier side will induce melting. The glacier starts to slip, meltwater flows around the obstacle to the down glacier side.

35
Q

What process do cold based glaciers move by?

A

Internal deformation.

36
Q

What is internal deformation?

A

The response of individual grains of ice within the glacier to stop overlying pressure.

37
Q

What are the two types of internal deformation?

A

Intergranular flow, laminar flow.

38
Q

What is intergranular flow?

A

The displacement of ice grains relative to each other, by constant rotation.

39
Q

What is laminar flow?

A

Layers of ice within the glacier slipping over each other.

40
Q

What is ice creep?

A

The deformation of ice in response to stress - as a result of ice thickness increased, and surface slope angle.

41
Q

What can happen when ice is unable to deform quickly?

A

Can lead to fracture and ice faulting.

42
Q

What is extensional flow?

A

The gradient of ice becomes steeper, so ice moves faster, stretching the ice mass, making it thinner.

43
Q

What is compressional flow?

A

Gradient is reduced, as leading ice, slows down, enabling ice behind to catch up, leading to thickening of ice.

44
Q

How does slope angle affect glacial movement?

A

Steeper gradient - Faster movement of glaciers. Less steep angles - slower movement. Gentle slopes mean basal sliding.

45
Q

How does thermal regime affect glacial movement?

A

Cold based glaciers flow more slowly, as they’re frozen to the bedrock. Warm based glaciers move faster.

46
Q

What is a glacial surge?

A

A period of rapid movement when a snout advances up to 1,000 times faster than normal, because of a change in the flow pattern of sub glacial meltwater.

47
Q

What is a example of a glacial surge?

A

Mudrow Glacier, Alaska. The last glacial surge at this glacier, before 2021, was 60 years ago. Surface of glacier became cracked, crevasses could be seen along the whole length.

48
Q

What are the first two stages of a glacial surge?

A

Water builds up underneath glaciers during a phase of normal glacier flow. During winter, subglacial meltwater channels are closed, increasing ice accumulation.

49
Q

What are the third and fourth stages of a glacial surge?

A

During summer, weight of ice accumulation is so great, subglacial meltwater channels don’t open. Pressure melting point separates basal ice from its bed, which lubricates it, causes overlying ice to flow more easily.

50
Q

What are the last two stages of a glacial surge?

A

Abundance of water increases water pressure of subglacial sediment, adding to rapid movement. Surge occurs, and glacier resumes normal flow.

Glaciated Landscapes (13 decks)

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