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geography > ❄️ glaciation sg1 > Flashcards

❄️ glaciation sg1 Flashcards

1
Q

what is a glacier

A

land based ice mass which is thick enough to flow under its own weight

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2
Q

how much of the earths surface is covered in glaciers

A

10%

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3
Q

where are glaciers found

A
  • high altitude (height above sea level)
  • high latitude (distance from equator)
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4
Q

what kind of system is a glacier

A

open system

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5
Q

inputs of matter into a glacier

A

precipitation
avalanches
rockfall

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6
Q

inputs of energy into a glacier

A

thermal energy from sun
kinetic energy from ice moving & wind
potential energy from high altitude

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7
Q

processes of erosion in a glacier

A

abrasion
plucking
freeze thaw weathering

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8
Q

outputs in a glacier

A

meltwater
evaporation
calving ice bergs
glacial drift
sublimation
debris
thermal energy from friction

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9
Q

what is accumulation

A

gain of snow and ice to a glacier over a long period of time

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10
Q

what is the zone of accumulation

A

upper reaches of a glacier where accumulation > ablation

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11
Q

what is ablation

A

loss of ice through melting, calving, evaporation & sublimation

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12
Q

what is the zone of ablation

A

lower altitudes where ablation > accumulation

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13
Q

what is the equilibrium line

A

seperates 2 zones, accumulation = ablation

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14
Q

what is the glacier mass balance

A

difference between accumulation and ablation
- winter = positive mass balance
- summer = negative mass balance

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15
Q

what is dynamic equilibrium

A

where short term changes and inbalance, balance out over time due to negative feedback loops

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16
Q

what is diagnesis

A

1: low density fresh snowfall traps a lot of air when it survives the year as it becomes denser
2: layers of snow build onto each other so air is expelled so density increases due to pressure melting and compression
3: over a long period of time (30-40 - 100 years) glacial ice forms, becomes blue rather than white

17
Q

what is a valley glacier

A

‘rivers’ of ice which flow down from high mountains in river valleys
- 10-30km long
- eg Swiss Alps
- could be outlet glaciers from ice sheets

18
Q

what is an ice sheet

A

areas of thick ice spread out over land and sea
- 69% of worlds ice
- 50,000 km^2 of ice
- largest accumulation of ice
- eg Antarctica

19
Q

what is pressure melting point

A

temperature at which ice is at the verge of melting due to pressure (does not have to be 0^c, could be lower)

20
Q

what is a warm based glacier

A

high altitude locations
areas of steep relief
water acts as lubricant
ice moves freely and erodes rock
moved up to 1000m per year

21
Q

what is a cold based glacier

A

high latitude locations
low relief ice frozen as base so little movement
little erosion
only moves a few meters per year

22
Q

what is basal sliding

A

main type of movement for warm based glaciers (90% of their movement

23
Q

what is slippage

A

when base is melted bc PMP has been reached so water acts as lubricant to reduce friction. water could also come from moulins

24
Q

what is regelation

A

when base of ice meets a rock outcrop.
before rock: pressure increases = high temps = ice deforms & goes over rock like putty
after rock: pressure decreases = water refreezes = FTW

25
Q

what is substrate deformation

A

when meltwater seeps into sediments under glacier so sediment becomes saturated so acts as lubricant so ice will slide (kind of like roller boots)

26
Q

what is internal deformation

A

main type of movement in cold based glaciers due to little meltwater. slow movement

27
Q

what is intergranular slip

A

weight of ice makes individual ice crystals change shape. ice crystals become flat so slide over each other. ice moved downslope due to gravity

28
Q

what is laminar flow

A

the movement of individual layers within the glacier (between annual accumulation layers)

29
Q

what is extending flow

A

ice moves over steep slope so is unable to deform quickly so ice fractures as ice in front pulls away from ice behind it

30
Q

what is compressing flow

A

when gradient is reduced so ice thickens and flowing ice pushes over slow moving ice in front of= thicker ice = more erosion

geography (18 decks)

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