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geography > What processes operate within glacial systems? > Flashcards

What processes operate within glacial systems? Flashcards

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1
Q

what are some glacial inputs

A

precipitation
Avalanches
meltwater
rock debris

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2
Q

what are the glacial stores/ processes? (General)

A

the moving glacier erodes transports and deposits rock debris

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3
Q

what are the glacial outputs

A

meltwater
icebergs
water vapour
rock debris

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4
Q

what is accumulation

A

the input of snow and ice into a glacier

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5
Q

what processes cause accumulation

A

precipitation
wind deposits
avalanches

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6
Q

what is ablation

A

the output of snow and ice from a glacier

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7
Q

What are some ablation processes?

A

melting
ice berg calving
sublimation
evaporation

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8
Q

what is iceberg calving

A

when chunks of ice break off at the terminus, or end. of the glacier

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9
Q

what can cause accumulation rate to vary

A

high levels of inputs
low average temperatures
low levels of insolation
low wind speed

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9
Q

where are the highest rates of ablation

A

higher altitudes
on slopes with a poleward aspect

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10
Q

where/ what is the accumulation zone?

A

the uppermost section where there is greater accumulation than ablation

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11
Q

where/ what is the ablation zone

A

lower part of the glacier when the rate of ablation is higher then accumulation

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12
Q

what is the equilibrium line

A

the boundary between zones where rate of accumulation and ablation are equal

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13
Q

how is glacial mass balance calculated

A

subtracting total ablation away from total accumulation for the year

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14
Q

what is positive mass balance

A

when total accumulation exceeds ablation

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15
Q

what is negative mass balance

A

when ablation is higher than accumulation

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16
Q

how does the glacier move in positive mass balance

A

the glacier will advance as there is greater ice content

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17
Q

how will the glacier act when in negative mass balance

A

it will retreat as the input into the glacier is reduced

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18
Q

what will happen to the snout when in dynamic equilibrium

A

the glacier snout will remain stationary

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19
Q

what are feedback loops

A

deviations in in puts or outputs that move systems away from a balanced state

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20
Q

what do negative feedback cycles act to do?

A

minimise the effect of the new input, in order to re-establish stability

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21
Q

what is an example of a negative feedback loop

A

more snow in accumulation zone
increased ice volume, glacial advance
more ice volume in ablation zone
more ablation
overtime output of meltwater equals snow input
return to balance

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22
Q

what do positive feedback loops do?

A

Amplify the initial change and might cause a shift in the system to a new state of equilibrium

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23
Q

what is an example of a positive feedback loop (glacier)

A

positive mass balance
surface area increases
increased albedo
reduced air temperatures
increased accumulation
initiating positive feedback (continued advance)

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24
Q

how fast does the Jakobshavn glacier moving

A

20 meters per day at its snout

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25
Q

what affects glacial movement

A

temperature of ice
if PMP is satisfied

26
Q

what happens to the melting point of ice with increased depth of a glacier

A

the temperature will be fractionally lowered due to the pressure of the overlying ice

27
Q

what does the meltwater do on temperate glaciers

A

acts as a lubricant between the rock and the ice allowing the glacier to move

28
Q

what is the process where meltwater acts as a lubricant for the ice

A

Basal slip

29
Q

what glacier does basal slip happen at

A

most temperate glaciers

30
Q

why cant PMP be satisfied in polar glaciers

A

Too cold to produce melt water

31
Q

what happens between the bedrock and a polar glacier

A

the ice is frozen to the bedrock
movement only occurs by internal deformation

32
Q

what is internal deformation

A

gravity and the pressure of the ice in the accumulation zone cause ice crystals to slide over each other in a series of parallel planes in a ‘crumpling deformation’

33
Q

what can internal deformation form

A

deep crevasses at the surface

34
Q

what factors control the rate of glacial movement

A

ice temperature
rate of ablation
ice thickness
precipitation levels
bedrock permeability
ice and slope gradient

35
Q

how does ice temperature influence movement

A

colder ice moves more slowly as it does not deform as easily and stays stuck to the bedrock more

36
Q

how does rate of ablation affect movement

A

The more melt water there id the faster the movement as basal slippage increases

37
Q

how does ice thickness affect ice glacier movement

A

when the ice is 50m thick plastic flow begins.
the grater the thickness the greater the pressure causing faster movement (more melt water)

38
Q

how does precipitation level affect glacial movement

A

higher snowfall leads to greater accumulation and faster movement

39
Q

how does bedrock permeability affect glacial movement

A

if the bedrock is permeable, then meltwater may be able to soak away slowing the glacier

40
Q

what is the process of water soaking into rocks

A

percolation

41
Q

will movement be slow or quick over clay

A

quick as clay is deformable

42
Q

how does ice and slope gradient affect movement

A

the steeper the slope the faster the movement due to gravity

43
Q

what type of glacier is Briksdalbreen

A

a temperate/ warm based glacier

44
Q

what ice cap feeds the Briksdalsbreen glacier

A

Jostedalsbreen ice cap

45
Q

what is the altitude range for the brikdalsbreen glacier

A

1910m to 350m

46
Q

what erosional processes take place in a glacial environment

A

frost shattering
abrasion
plucking
fracture/traction
dilation
meltwater erosion

47
Q

What are the 3 areas in a glacier where material is transported

A

Sub-glacially
En-glacially
Supra-glacially

48
Q

Where does deposition occur in a glacier?

A

At the snout
Where surrounding ice sublimates
Friction against the base

49
Q

What is a relict glacial landscape

A

A area not currently glacially active but features fossilised glacial landforms due to past glacial activity

50
Q

What are macro-scale landforms? (definition)

A

Large scale landforms that have been created by a combination of glacial processes over time

51
Q

What is an example of a macro scale landform

A

Cirques
Arêtes
Pyramidal peaks
Terminal moraines
(Ice sheet eroded landscapes- all features combined)

52
Q

What are meso-scale landforms

A

Intermediate scale landforms that have been created mostly by erosion but can also be created by meltwater erosion

53
Q

What are some examples of meso-scale landforms

A

Roches moutonnes
Drumlins
Kames
Eskers
Kettle holes (fluvioglacial landform)

54
Q

What are micro-scale landforms? (Definition)

A

Small scale landforms in some cases quite small in size

55
Q

What are some examples of micro-scale landforms

A

Striations
Chatter marks
Erratics

56
Q

What are the 4 main glacial environments we need to know about?

A

Subglacial
Ice marginal
Proglacial
Periglacial

57
Q

What is the subglacial environment

A

The environment beneath the glacier ice subject to immerse pressure from the overlying ice

58
Q

What is the ice marginal environment

A

Environment at the edge of the glacial ice where a combination of a glacial and fluvioglacial processes take place

59
Q

What is a proglacial environment

A

Located at the front of the glacier, ice cap or ice sheet dominated by fluvioglacial activity

60
Q

What is a Periglacial environment

A

Environment found near the glaciers dominated by freeze thaw activity but not dominated by moving ice

61
Q

What are past glacial landscapes useful for

A

Allows us to see exact position and extent of ice cover
This process is called inversion modelling

62
Q

what processes of glacial erosion are there

A

plucking
crushing
abrasion
fluvio-glacial erosion

63
Q

What is frost heave?

A

Physical weathering process involving the cyclic freezing and thawing of water in soil or rock
Heave is the upward movement of the ground due to ice crystal/lenses in the soil

geography (103 decks)

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