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physical geography > physical part 1 > Flashcards

physical part 1 Flashcards

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1
Q

glacial definition

A

when there is lots of glaciers in middle and high latitudes.
Lasting tens of thousands of years

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2
Q

inter-glacial definition

A

period of less glaciers due to climate warming
10,000 years

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3
Q

quaternary definition

A

period of time
the last 2.6 million years

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4
Q

holocene definition

A

last 11-12,000 years

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5
Q

epoch definition

A

geological time period
smallest category

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6
Q

ice age definition

A

period of cold climate

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7
Q

cryosphere definition

A

the frozen water part of the Earth’s atmosphere

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8
Q

ice sheet definition

A

on top of land
e.g. Antarctica

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9
Q

sea ice definition

A

sits on top of the sea

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10
Q

glaciers definition

A

found in the mountains

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11
Q

how much of the earth today is covered in ice

A

10%

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12
Q

how often are ice ages

A

every 200 - 250 million years

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13
Q

what was the last ice age called

A

quaternary ice age

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14
Q

extent of ice from Britain from last ice age

A

-upto 2 miles deep
-melted in Britain about 11,500 years ago
-this ice shaped most of out landscape

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15
Q

what are system comprised of

A
  • inputs
  • stores
  • throughputs
  • outputs
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16
Q

are glaciated landscapes open or closed?
and why?

A

open systems
Energy and matter can enter as inout and leave as output

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17
Q

stores in a glacier

A

-ice
-water
-debris accumulation
-movement of ice - due to gravity

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18
Q

inputs of a glacier

A

-potential energy - height/gravity
-kinetic energy - from wind
-thermal energy - from sun
-precipitation
-deposition, weathering, mass movements, avalanches

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19
Q

outputs of a glacier

A

-sediment - deposition and erosion
-calving
-ablation - melting, evaporation, sublimation

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20
Q

energy inputs in a glacier system

A

-thermal from sun - evaporation
-gravitational potential energy - ice mass are elevated
-kinetic energy - debris and snow as avalanches
-geothermal heat energy - at base of glacier

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21
Q

energy throughputs in glacier system

A

-gravitational energy - ice moves down hill
-frictional heat energy - ice movement - increase temp
-release of latent heat - when meltwater freezes

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22
Q

energy stores in a glacier

A

gravitational potential energy - stored in rock

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23
Q

what is energy outputs in a glacier

A

when energy leaves glacial system in form of heat

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24
Q

material inputs in a glacier

A

precipitation of snow/rock debris
e.g. form avalanche

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25
Q

material throughputs in a glacier

A

movement of snow, ice, meltwater, and rock debris

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26
Q

material stores in a glacier

A

storage of ice, meltwater, and rock debris above, beneath or below the glaciers

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27
Q

material outputs in a glacier

A

water vapour, water, ice, rock debris and Aoelian (by wind) processes

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28
Q

Flows of solar energy through the glacial system

A

-evaporation and sublimation (output)
-without this there would be no snowfall

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29
Q

flows of variations in solar energy in a glacial system

A

determines differences in high latitudes ‘v’ low latitude glaciers - greater sow accumulation (more glacier)

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30
Q

flows of wind energy in a glacial system

A

importance in role of ‘snow blow’ and snow formation and at local scale.

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31
Q

flows of gravity through a glacial system

A

provide potential energy. determine flow of kinetic energy as ice/rock debris flows downhill.

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32
Q

flows of geothermal energy through a glacial system

A

influence gravitational energy available - causing uplift.
might also provide meltwater at base of glacier encouraging movement

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33
Q

system feedback in glacial system

A

characterised by feedback.
if [inputs=outputs] then the system is at equilibrium, i.e. glacier stays same size.
glaciers are dynamic equilibrium - ‘self regulates’

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34
Q

positive feedback definition

A

a change creates a response in the system reinforces the effect of the original change. - amplifying that change and creating a ‘snowball effect’ which leads to new state of equilibrium

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34
Q

negative feedback definition

A

system will self-regulate to re-establish stability through counteracting the change and will maintain a state of equilibrium

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35
Q

albedo definition

A

expression of the ability of the earths surfaces to absorb the suns rays
water absorbs more light (lower albedo)
ice absorbs less light (higher albedo)

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35
Q

what is the mass balance / glacial budget

A

the glacier system constantly adjusts to the changes in the balance between accumulation and ablation

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36
Q

the balance year for calculating net balance

A

Time from minimum mass of one year to the minimum mass of next year

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37
Q

positive mass balance

A

when accumulation is greater than ablation.
gain of ice i.e. in winter
results in glacier advancing

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38
Q

negative mass balance

A

ablation is greater than accumulation.
loss of ice i.e. in spring or summer
glacial retreat (maybe)

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39
Q

equilibrium in glacier system

A

accumulation= ablation
glacier remains stable equilibrium
if net balance is negative, it moves under gravity

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40
Q

what are the two zones a glacier can be divided into?

A

accumulation zone
ablation zone
separated by the equilibrium line altitude (balance of inputs and outputs)

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41
Q

what are the two zones a glacier can be divided into?

A

accumulation zone
ablation zone

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42
Q

accumulation zone

A

where accumulation exceeds ablation

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43
Q

ablation zone

A

where ablation exceeds accumulation

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44
Q

factors influencing the growth of ice sheets

A
  • accumulation of snow and ice formation
  • climate - cold winter - hot summer
  • further snow - gradually snow turn into ice, fern, Neve, glacial ice
  • aspect - direction the glacier is facing
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45
Q

factors influencing the decay of ice sheets

A
  • ablation
  • summer temperature is higher
  • outputs exceed inputs
  • loss of ice resulting from calving
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46
Q

sublimation

A

when ice changes directly from ice to water vapour without being a liquid.
Specific case of vaporisation

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47
Q

temporal differences in mass balance

A

change
short term variations
long term variations

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48
Q

short term variations

A

instant, day, monthly, year
mass balance varies throughout the year, glaciers typically get more accumulation in winter and more ablation in summer

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49
Q

long term variations

A

100s, 1000s of years
cumulative mass balance is mass of glaciers at stated time, relative to mass at earlier time.
These measurements give us detailed info about climate change

50
Q

what does glacier analysis show

A

the vast majority of European glaciers are receding, with the rate of recession accelerating since the 1980s

51
Q

precipitation in high latitude areas

A

high pressure areas/bands with low levels of clouds and low precitipation

52
Q

precipitation in high altitude areas

A

increase in altitude means clouds may condense and result in precipitation

53
Q

Lithology definition

A

what rocks are made of
e.g. limestone, granite, basalt, sandstone

54
Q

Cracks in rocks

A

-more rocks means more easily eroded
-jointing (stress)
-bedding (water build up in between layers)
-faulting (techtonic plate movement)

55
Q

Impact of climate on glaciers?

A
  • wind
  • precipitation
  • temperature
56
Q

How does wind affect glaciers?

A
  • can carry erosion, transportation, and deposition
  • known as aeolian processes
  • can shape glaciated landscapes
57
Q

How does precipitation affect glaciers?

A

-major input
- determine glacial mass balance
- vary seasonally

58
Q

How does temperature affect glaciers?

A
  • if temp rise above 0, there will be increase in ablation and higher outputs (mainly in summer months
  • high latitude - temp might never rise above 0
59
Q

Joints and faults

A

a fault is due to techtonic movement
joint is due to stress

60
Q

Impact of geology on glaciers

A
  • lithology - refers to physical and chemical composition of rock
  • structure - properties of individual rock
61
Q

impact of latitude on glaciers

A

-high latitude - cold dry climate, little seasonal variation - larger stable ice sheets (Greenland)
-low latitude but high altitude - variable temp and higher precipitation - more dynamic glaciers which shape the glaciers

62
Q

impact of altitude on glaciers

A
  • glaciers can be found in high latitudes due to reduction in temp with altitude
  • decreases at rate 0.6C/100m increase in height
63
Q

impact of relief on glaciers

A
  • steeper the relief - the more potential energy (gravity) - glacier will have more energy to move downslope
64
Q

impact of aspect on glaciers

A
  • if slope is facing away from sun, temp might never go above 0C
  • less melting
  • more likely to have positive mass balance, so glacial advance
65
Q

what is the snowline?

A

Where snow starts on a mountain varies depending on climate

66
Q

what are the different types of glacier?

A
  • ice sheets
  • ice caps
  • mountain ice caps
  • ice field
  • valley glacier
  • corrie glacier
  • piedmont glacier
  • ice shelf
67
Q

ice sheets

A
  • e.g. Greenland and Antartica
  • 96% of worlds ice is held here
  • largest ice feature
  • above 50,00km2
  • only two exist
68
Q

ice caps

A
  • e.g. Vatajokull, Iceland
  • huge, dome shaped masses of ice on high plateaus
69
Q

Mountain ice caps

A
  • e.g. Kilimanjaro, Tanzania
  • mass of ice covering less than 50,00km2 on mountains
70
Q

ice fields

A
  • e.g. Patagonian Ice Field, Chile
  • large area of interconnected glaciers with only tallest peaks (nunataks) exposed
71
Q

Valley glacier

A
  • e.g. Athabasca Glacier
  • confined by valley sides
  • follow course of existing river valley
  • typically 10-30km long
72
Q

Corrie valley

A
  • small, on mountains
  • N-NE facing
  • cover area of 0.5 to 10km2
  • gradually erode hollows through glacial erosion
73
Q

piedmont glaciers

A
  • e.g. Malaspina glacier, Alaska
  • large lobes of ice
  • form when glaciers spread out on reaching lowland areas and escapes confines of the valley
74
Q

ice shelf

A
  • e.g. Ross Ice Shelf, Antarctica
  • extensions of ice sheets, reaching out over sea
  • can be up to 1000, thick
75
Q

tidewater glacier

A

a valley glacier that reaches the sea (small iceburgs)

76
Q

iceburg

A

floating mass of ice thats been calved from snout of glacier

77
Q

outlet glacier

A

glacier flowing out from an ice sheet, cap or field

78
Q

Glacieret

A

small mass of ice in hollows, accumulated due to snow drifts and avalanches. Existed for two consecutive summers

79
Q

Tributary glacier

A

small glacier flow into into a bigger one

80
Q

Ice apron

A

small, steep, smooth glacial masses that cling to high mountainsides

81
Q

how is snow made

A
  • snow traps air when it falls and has low density - 0.1g/cm3
  • snow accumulates and starts to compress. forces air out. Ice formation begins (diagenesis)
82
Q

how long does it take for glacial ice to form in Alaska

A

within 5 years

83
Q

how long does it take for glacial ice to form on Antarctica

A

150 to 200 years

84
Q

what is polar

A

a cold environment, mainly covered in snow

85
Q

what is temperate

A

a climate with no extreme temperature

86
Q

example of a cold based glacier

A

Meserve Glacier (Antarctica)

87
Q

characteristics of a cold based glacier

A
  • high latitude - 66°N to 90°N or S of equator
  • low relief
  • temperates throughout -17°C
  • glacier is frozen to the bed
  • PMP is not reached so no meltwater
  • movement of often a few metres a year
  • limited ablation and accumulation - less seasonal variation and high pressure
  • cold desert - less than 250mm of precipitation per year
  • little erosion due to slow movement
  • moves by intergranular flow or laminar flow
88
Q

how do cold based glaciers move

A

intergranular flow
laminar flow

89
Q

characteristics of warm based glaciers

A
  • high altitude - 2000-3000m above sea level
  • high accumulation in winter/ablation in summer (relief precipitation)
  • basal temp is around 0°C which is PMP
  • often steeper gradient
  • may move up to 2-3m per day
  • powerful erosion
  • mainly moves by basal slippage
90
Q

how do warm based glaciers move

A

basal slippage

91
Q

what does basal slippage in warm based glaciers result in

A
  • regelation slip
  • creep
  • glacial surge
92
Q

Meserve Glacier (Antarctica) details

A
  • small north flowing glacier in Antarctica
  • 7km long
  • tongues of the glacier terminate at almost vertical cliff
  • basal temperature is -17°C
  • silt rich basal layer - give distinct amber colour
  • slow movement - 0-few mm a day as frozen to the bed
93
Q

Athabasca glacier (Canada) details

A
  • one of the 6 glaciers which flow out of Columbia ice filed in the Canadian Rockies
  • moves at 2-3m per year
  • approx 6km long
  • 90-300m thick
  • basal temp is at PMP
  • most visited glacier - as close to the Icefields Parkway
  • Retreated overall 1.5km
94
Q

where do glaciers move fastest?

A

in the centre

95
Q

where do glaciers move the slowest

A

moves more slowly at the base and sides as the ice might have frozen to the valley base and sides. Obstructions may have created frictional resistance

96
Q

characteristics of ice

A
  • when it’s solid / rigid it will crack, forming crevasses
  • when under steady pressure it will deform and behave like plastic
97
Q

what is inter - granular flow? ( cold based glacier)

A

Individual ice crystals re-orientate and move in relation to each other

98
Q

what is laminar flow? ( cold based glacier)

A

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

99
Q

what is regelation slip?

A

I’ve melts to go over and obstacle and then refreezes on the other side (due to pressure)

100
Q

what is creep? (warm based glacier)

A

if ice encounters a large obstacle on bedrock floor, it’s put under increased strain and so deforms plastically and flows or creeps around the obstacle

101
Q

what is bed deformation (warm based glacier)

A

when ice is carried by saturated bed sediments moving beneath it. The water is under high pressure, carrying the ice above it

102
Q

what is sheer?

A

pressure from above along with slip

103
Q

what are crevasses a result of?

A

a) friction between glacier and valley sides and bed
b) tensions within the ice when there is a change in gradient

104
Q

what are crevasses

A

A deep tensional crack which can form in glacial ice. Rarely more than 30m deep

105
Q

what are the different types of crevasses

A
  • marginal crevasses
  • transverse crevasses
  • longitudinal crevasses
  • radial crevasses
106
Q

Marginal crevasses

A

Result of friction along valley sides as ice advances

107
Q

transverse crevasses

A

extend across glacier at steepening of gradient - common at ‘ice falls’

108
Q

longitudinal crevasses

A

valley becomes wider and ice surface widens to fill the valley
Long crevasses

109
Q

how much does water expand when frozen?

A

8-9%

110
Q

what is frost shattering weathering

A
  • water trapped in rock pores will freeze and expand at very low temperature
  • expansion causes stress which causes rock to disintegrate to small bits
111
Q

what is pressure release

A
  • as melting causes a reduction in the weight of overlaying ice, the underlying rock expands
  • it fractures parallel to the surface
  • these fractures (dilation) are sometimes known as pseudo-bedding planes
112
Q

what is chemical weathering

A

weathering through chemical reactions/ change can produce weak residues of materials from rock which is then easily removed by erosion

113
Q

when is chemical weathering particularly importanr

A

when meltwater is present and in contact with rock

114
Q

what are the types of chemical weathering in a glacial environment

A
  • oxidation
  • solution
  • carbonation
  • hydration
  • hydrolysis
115
Q

what is carbonation

A
  • carbonic acid reacts with calcium carbonate in rock (limestone) to produce calcium bicarbonate
116
Q

what is oxidation

A
  • minerals in rock react with oxygen
  • either O2 in water or air
117
Q

what is hydrolysis

A

minerals in rock can undergo a chemical reaction when in contact with water.
It’s the hydrogen in water that causes this

118
Q

what is solution

A

any process where a mineral dissolved in water is known as solution
Some become soluble when water is more acidic

119
Q

what is hydration

A

when water molecules are added to rock minerals, they create minerals of a larger volume
Causes flaking

120
Q

how likely is biological weathering in glacial areas

A

generally of low significance because plant and animal activity are limited by the low temperatures

121
Q

what are the two types of biological weathering

A
  • tree roots
  • chelation (organic acids)
122
Q

tree roots - biological weathering

A
  • the roots grow into cracks / joints in the rock, they exert pressure, forcing the rock apart
123
Q

chelation - biological weathering

A
  • as plant and animal litter decomposes, organic acids are released
  • causes soil to become more acidic
  • react with minerals and break rock down

physical geography (4 decks)

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