EQ2- What Processes Operate Within Glacier Systems

Question 1

What are the inputs into the glacier system

Answer 1

Direct precipitation - form of snowfall which is compacted to form glacial ice

Avalanches from mountains - massive downhill movement of snow and ice which can be triggered by heavy snowfall, steep slopes and vibrations

Wind deposition - strong winds blow snow onto the glacier

Question 2

What are the stores and flows which operate in the glacier system

Answer 2

Main stores of snow and ice - may be seasonal variations in the size of these stores

Flows - processes like evaporation , sublimation , meltwater flow and glacial movement are flows of energy and material

Question 3

What are the outputs which operate in the glacier systems

Answer 3

Water : results from melting close to the glaciers snout

Ice shelves : the ice front extends over water and calving occurs where chunks of ice break off to form icebergs

Evaporation and sublimation also occurs

Question 4

Explain the process of dynamic equilibrium in the glacier system

Answer 4

The boundary between the accumulation zone (inputs) and the ablation zone (outputs)

The equilibrium line will move depending on the state of the glacier

Question 5

Explain how energy effects the operation of glacier systems

Answer 5

A glaciers mass combines with the force of gravity to generate potential energy

The energy is converted to kinetic to allow the glacier to move and carry out the process of erosion ,transportation and deposition

Question 6

Explain how feedback loops effect the operation of glacier systems

Answer 6

Negative feedback loops regulate systems to restore dynamic equilibrium
Positive feedback enhances and speeds up the process

Both feedback loops occur in glacial systems

Question 7

Define accumulation

Define abaltion

Answer 7

Is where there are inputs into the glacial system

The outputs in a glacial system

Question 8

Explain the factors that cause variations in the rate of accumulation

Answer 8

Accumulation varies with climate
Accumulation rates increase when there is high levels of precipitation, low average temperatures, low levels of insolation and strong winds
Strong winds at high altitudes causes snow to be blow into hollows
Highest rates of accumulation is found at high altitudes on slopes facing away from the sun (less insolation)
As temperatures are low and other losses like sublimation are low, meltwater is likely to refreeze

Question 9

Explain the role of feedback loops in the variations in the rate of accumulation

Answer 9

Positive feedback amplify change
If a glacier has a positive mass balance , there will be an increase in ice albedo
Causes a further reduction in temperature , increasing accumulation and initiating a cycle where the glacier will continue to grow and advance

Question 10

What is a positive mass balance

What is a negative mass balance

Answer 10

When accumulation is greater than ablation , the glacier advances

When ablation is greater than accumulation, the glacier retreats

Question 11

Explain the factors that cause variations in the rate of ablation

Answer 11

Rate of ablation varies with climate
Found further downslope so temperatures will be higher and melting occurs
Snow is lost to glacial meltwater and evaporation/sublimation
In polar regions large ice shelves extend over water, calving can occur when ice breaks off to form and iceberg. High rates of ablation means large masses of ice can be lost at one

Question 12

Explain the role of feedback mechanisms with the factors which cause variations in the rate of ablation

Answer 12

Negative feedback is about trying to restore a dynamic equilibrium
When ablation is higher than accumulation , negative feedback operates to try and restore balance
For example high rates of ablation causes increased snowfall due to negative feedback

Question 13

What are the processes in warm based glacier movement

Answer 13

Moves by both basal slip and internal deformation

Question 14

What are the processes in cold based glacier movement

Answer 14

Move only by internal deformation

Question 15

Explain the process of basal slip in glacial movement

Answer 15

Occurs in warm based glaciers
Occurs when the base of the glacier reaches pressure melting point
Meltwater is present and acts as a lubricant allowing the glacier to move quickly over the bedrock
Accounts for 75% of warm based glacier movement

Question 16

Explain the two processes of enhanced basal creep and regelation as processes of basal slip in warm based glaciers

Answer 16

Basal creep occurs over a large bedrock (greater than 1m wide)
When the glacier and the bedrock meet there is increased pressure and makes the ice plastically deform and engulf the bedrock
It very slowly moves over it and takes its shape

Regelation occurs over a small obstacle (less than 1m wide) when the meeting of the glacier and bedrock causes pressure
This causes heat and the base of the glacier melts to form glacial meltwater to act as a lubricant to move over the obstacle.
The meltwater refreezes further downslope where there is less peessure

Question 17

Explain the process of internal deformation and how it effects glacial movement

Answer 17

Accounts for 100% of the cold based glacier movement and 25% of warm based glacier movement.
This occurs when the weight of the glacier and gravity (shear stress) cause the ice crystals to deform
The glacier moves downhill very slowly

Question 18

Explain the two processes of internal deformation and how it causes glacier movement

Answer 18

Inter- granular movement is when individual crystals slip and slide over each other causing movement downhill

Intra- granular movement is when individual crystals become deformed due to stress of ice and moves downhill gradually.

Question 19

Explain the processes of extensional and compressional flow in basal slip and how it effects warm based glacier movement

Answer 19

Extensional flow is at the head of the glacier where there is GPE
This makes ice move quickly causing tension and ice to fracture and slip downwards
Forms seracs

Compressional flow occurs when the fast moving ice pushes down of slower ice and compresses it.
The high pressure causes the ice to fracture into layers, causing transverse crevaces to form.

Question 20

Explain the process of surges in basal slip and how it causes warm based glacier movement

Answer 20

When a glacier advances substantially up to 200m per day
The most common cause is enhanced basal sliding triggered by the build up of meltwater
In Iceland geothermal energy and subglacial bed deformation (glacier moves over rock) is a cause of surges

Question 21

How does ice move in response to the factor of lithology (rock type)

Answer 21

In temperate zones movement is faster over impermeable rock than permeable, as basal meltwater is retained
If the bedrock is permeable meltwater would be able to percolate and it is prone to bed deformation

Question 22

How does ice move in response to the factor of altitude

Answer 22

Altitude effects the temperature and precipitation inputs
The greater the precipitation the lower the temperature.
High snowfall leads to greater accumulation and faster movement

Question 23

How does ice move in response to the factor of gravity/gradient (slope)

Answer 23

Gravity and gradient is directly related to flow

Gravity encourages ice to move, the steeper the gradient the greater the pull of gravity

Question 24

How does ice move in response to the factor of ice temperature

Answer 24

Colder ice moves slower than warmer ice as it does not deform as easily and is more stuck to the bedrock

Question 25

How does ice move in response to the factor of ice thickness

Answer 25

The greater the thickness, the more pressure created and the faster the movement.
Size of ice can effect the rapidity of response
Mass effects the force needed to overcome friction

Question 26

How does ice move in response to the factor of mass balance (rate of ablation)

Answer 26

Mass balance effects the equilibrium and whether it advances or retreats.
The more meltwater there is causes faster movement, due to basal slippage.

Question 27

How does ice move in response to the factor of feedback mechanisms

Answer 27

Positive feedback amplifies change
An example is that continued increased friction causes further basal slip, which continues to happen
Negative feedback restores dynamic equilibrium
An example is that basal slip reduces ice thickness and leads to reduced pressure melting and basal slip.

Question 28

Explain the glacial process of glacial erosion

Answer 28

Is the removal of material by ice and meltwater

Question 29

What are the different processes involved in glacial erosion

5

Answer 29

Abrasion : individual stones eroding rock

Plucking - widening of joints by fracture and plucking of frozen rock from glacier

Fracture and traction - crushing effect of the weight of ice passing over rock and causing thawing

Dilation - overlying material is moved due to fractures in the rock

Meltwater erosion - mechanical or chemical where meltwater dissolves minerals

Question 30

Explain the glacial process of glacial debris entrainment

Answer 30

Is the incorporation of debris into the glacier from supraglacial or subglacial sources

Question 31

Explain the supraglacial and subglacial sources of glacial debris entrainment

Answer 31

Supraglacial sources include material falling from hillsides or atmospheric fallouts from volcanoes

Subglacial sources include include material eroded from the glacier bed and valley walls

Question 32

Explain the glacial process of transport

Answer 32

Is where rock debris is transported on the ice surface , within the ice and at the base of the glacier

Water also transports material

Question 33

Explain the glacial process of deposition

Till and Fluvio-glacial

Answer 33

Till is sediment deposition directly by glacier ice

Fluvio-glacial debris is deposited by glacial meltwater

Question 34

Explain micro-scale landforms

Examples

Answer 34

Are small scale landforms up to 1m long

E.g. stritations, glacier grooves and chatter marks

Question 35

Explain meso-scale landforms

Answer 35

Are medium scale landforms

E.g. drumlins and eskers

Question 36

Explain macro-scale landforms

Answer 36

Are Large scale landforms

E,g, criques and pyramidal peaks

Question 37

Explain a subglacial glacial environments

Answer 37

Is the environments beneath the glacial ice which has immense pressure from the overlying weight of ice

Question 38

Explain an ice marginal glacial environment

Answer 38

Is found at the edge of glacial ice where glacial and fluvio-glacial processes occur

Question 39

Explain a proglacial glacial environment

Answer 39

Is an environment at the front of the glacier which has fluvioglacial processes occur

Question 40

Explain a periglacial glacial environment

Answer 40

Is environments near glaciers and dominated by freeze -thaw processes

Question 41

Explain a upland glacial landscape

Explain a lowland glacial landscape

Answer 41

Are found at higher altitudes

Are found at lower altitudes

Question 42

What are active glacial landscapes

Answer 42

Experience glaciation , active glacial processes and landform development

Question 43

What are relict glacial landscapes

Answer 43

Feature fossilised glacial landforms