5.2: the processes that case glacier movement Flashcards

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1
Q

What is the fundamental cause of ice movement?

A

Gravity

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2
Q

What is the accumulation zone?

A

the area above the firn line, where snowfall accumulates and exceeds the losses from ablation

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3
Q

What is the Firn Line

A

A line across the glacier, from edge to edge, that marks the transition between exposed glacier ice and the snow-covered surface of a glacier

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4
Q

What is the ablation zone

A

Refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, blown snow, avalanche, and any other ablation.

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5
Q

Describe what shear stress is

A

force tending to cause deformation of a material by slippage along a plane or planes parallel to the imposed stress.

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6
Q

Describe how a glacier moves.

Reference the accumulation zone, ablation zone, shear stress

A

As ice mass builds up in an accumulation zone the weight of the snow and ice exerts an increasing downslope force due to gravity - known as shear stress
Shear stress increases as the slope angle increases
Once the shear stress is great enough to overcome the resisting forces of ice strength and friction, the glacier ice pulls away and moves downward away from the zone of accumulation where it eventually looses mass

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7
Q

Where are warm based glaciers found?

A

temperate maritime climates

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8
Q

Warm wet based glaciers experience greater snowfall in winter and more rapid ablation in the summer; therefore the imbalance between accumulation and ablation zones is …? so the glacier ice must move downslope more rapidly to maintain …? with the slope angle

A
  1. greater
  2. equilibrium
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9
Q

In cold based polar glaciers the slower the rates of accumulation, and especially ablation, result in a …? gradient of equilibrium and ..? ice movement

A
  1. smaller
  2. slow
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10
Q

Basal Sliding relates to the presence of …? beneath a glacier

A

meltwater

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11
Q

Basal sliding is movement that only applies to …? based glaciers?

A

warm-based glaciers

it can’t occur where the glacier is frozen to the bed

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12
Q

Describe the process of basal sliding

Refer to meltwater and friction in your explanation

A

The meltwater acts a lubricant reducing friction with both the entrained debris and underlying bedrock (this is known as slippage)

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13
Q

Regelation Creep (sometimes known as …?), occurs as basal ice deforms under …? when encountering obstructions such as rock steps. As a glacier moves the pressure on the basal ice will increase and it will ..?. Once the glacier had flowed over the obstruction the pressure is …? and the water refreezes

A
  1. slip
  2. pressure
  3. melt
  4. lowered
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14
Q

What base type of glaciers move by internal deformation?

And what region of the world are they found in?

A

Cold-based polar glaciers

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15
Q

internal deformation which has 2 main elements:

  1. Intergranular flow
  2. Laminar flow

Explain them both

A
  1. Intergranular flow when individual ice crystals deform and move in relation to each other
  2. Laminar flow when there is movement of individual layers within the glacier
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16
Q

When ice creep can’t respond quickly enough to a glaciers speed of movement what occurs

A

ice faulting occurs causing crevasse’s at the surface

A crevasse is a deep crack that forms in a glacier or ice sheet that can be a few inches across to over 40 feet

17
Q

Warm based glaciers have a …? velocity of movement than the …?-based glaciers because of the addition of basal sliding to internal deformation. Even greater velocities are reached when a warm-based glacier moves over deformable …?

A
  1. greater
  2. cold
  3. sediment
18
Q

What 5 factors impact glacial movement?

A
  1. Altitude
  2. Slope
  3. Lithology
  4. Size
  5. Mass balance
19
Q

How does Altitude impact glacial movement?

A

affects the temperature and precipitation inputs

20
Q

How does Slope impact glacial movement?

A

is directly related to flow - steeper slopes lead to faster speeds

21
Q

How does Lithology impact glacial movement?

A

can affect basal processes and the possibility

22
Q

How does Size impact glacial movement?

A

can affect the rapidity of the response

23
Q

How does Mass Balance impact glacial movement?

A

affects the equilibrium of the glacier and also whether its advancing or retreating

24
Q

What are outlet glaciers?

A

Outlet glaciers are valley glaciers that originate in ice sheets, ice caps, and ice fields.