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Geography 1 > Glaciers > Flashcards

Glaciers Flashcards

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1
Q

What are greenhouse and ice-house conditions?

A

greenhouse conditions - warmer interglacial conditions

ice-house conditions - colder glacial conditions

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2
Q

What are interglacials and glacials?

A

interglacials - warmer periods similar to present

glacials - colder ice-house periods within the Pleistocene

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3
Q

What are the 3 types of cold environments?

A
  • polar
  • alpine
  • periglacial
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4
Q

How are polar environments categorised?

A
  • glacial environment
  • high latitudes (Antarctic and Arctic)
  • extremely cold temperatures (-30/40 degrees)
  • low levels of precipitation
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5
Q

How are alpine environments categorised?

A
  • glacial environmentalists
  • high altitudes (in mountain ranges e.g. Alps)
  • high levels of precipitation
  • wide temperature range with frequent freeze-thaw
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6
Q

How are periglacial environments categorised?

A
  • non-glacial cold, dry environments with treeless vegetation (also called tundra)
  • found next to glacial areas e.g. Alaska
  • permafrost
  • high latitude or high altitude areas
  • seasonal temperature varies above and below freezing
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7
Q

What is the most recent ice age?

A

the Quaternary Ice Age - 2.6 million years to present

  • is subdivided into the Pleistocene - up to 10,000 years
  • the Holocene - began 10,000 years ago
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8
Q

How is the Pleistocene period characterised?

A
  • 50 glacial-interglacial cycles
  • last glacial maximum was 18,000 years ago (the Devensian)
  • last glacial advance in the UK was the Loch Lomond Stadial 12,000-10,000 years ago, marking the end of the Pleistocene period
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9
Q

What are the long term natural causes of climate change?

A 
- continental drift
Milankovitch cycles:
- eccentricity of the orbit
- axil tilt 
- wobble
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10
Q

How does continental drift cause climate change?

A

3 million years ago North and South American plates collided, re-routing ocean currents so warm Caribbean waters were forced northwest, creating the Gulf Stream

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11
Q

How does eccentricity of the orbit cause climate change?

A

shape of the Earth’s orbit varies from circular to elliptical every 100,000 years (earth receives less solar radiation in the elliptical orbit)

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12
Q

How does axil tilt cause climate change?

A

tilt of earth’s axis varies over 41,000 years, changing the severity of seasons

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13
Q

How does the earth’s wobble cause climate change?

A
  • earth wobbles as it spins on its axis, meaning the season at which earth is closest to the sun varies every 21,000 years (causing different severity of seasons) e.g. currently the northern hemisphere’s winter occurs when the earth is closest to the sun, causing milder winters
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14
Q

What are the short term natural causes of climate change?

A
  • variations in solar output (sunspots)

- volcanic activity

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15
Q

How do variations in solar output cause climate change?

A

sunspots, caused by intense magnetic activity in the sun’s interior, make the sun more active causing it to give off more energy - 11 year cycle

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16
Q

How does volcanic activity cause climate change?

A

large eruptions eject huge volumes of ash, sulphur dioxide, water vapour, CO2 into the atmosphere
these are globally distributed by winds
- this volcanic aerosol blocks sun radiation - cooling the earth
- this effect can take place for up to 3 years in the atmosphere

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17
Q

What is the cyrosphere?

A

the layer of the earth’s surface where water is in solid form (includes ice sheets, glaciers, sea ice, lake ice, permafrost and snow cover)
- important role in the Earth’s climate. Snow and ice reflect heat from the sun, helping to regulate our planet’s temperature, and many ecosystems depend on it

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18
Q

What are glaciers?

A

slow-moving bodies of ice in valleys that flow downhill under gravity - some are land-based (above sea level) e.g. Mer de Glace, the Alps
some are marine-based (below sea level)

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19
Q

What are the different types of ice mass? (8)

A
  • Piedmont glacier
  • cirque glacier
  • valley glacier
  • ice shelf
  • ice cap
  • ice field
  • ice sheet
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20
Q

What are the characteristics of an ice sheet?

A
  • complete submergence of topography, which forms a sloping dome of ice several km thick e.g. Greenland
  • up to 100,000 sq km
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21
Q

What are the characteristics of an ice cap?

A
  • smaller version of an ice sheet covering upland areas e.g. Vatnajokull, Iceland
  • up to 10,000 sq km
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22
Q

What are the characteristics of an ice field?

A
  • ice covers an upland area but isn’t thick enough to cover topography - many do not exceed the highland source e.g. Patagonia, Chile
  • up to 10,000 sq km
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23
Q

What are the characteristics of an ice shelf?

A

large area of floating glacier ice at the coast, where several glaciers have met the sea and merge e.g. Ross Ice Shelf, Antarctica
- up to 100,000 sq km

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24
Q

What are the characteristics of a valley glacier?

A
  • a glacier formed from ice sheets/cirques, that is confined between valley walls with a narrow tongue (may terminate in the sea) e.g. Athabasca, Canada
  • up to 1,500 sq km
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25
Q

What are the characteristics of a Piedmont glacier?

A
  • a valley glacier that has extended beyond the mountain valley into a flatter area, spreading out like a fan e.g. Malaspina, Alaska
  • up to 1,000 sq km
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26
Q

What are the characteristics of a cirque glacier?

A
  • small glacier occupying s hollow on the mountain side (carving out a cirque/corrie) e.g. Hodges Glacier, Georgia
  • up to 8 sq km
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27
Q

What is a glacial system?

A

the system of a glacier which includes inputs (precipitation, avalanches, rock debris, wind deposition), transfers, and outputs (melting, sublimation, calving, rock debris)

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28
Q

What is glacial mass balance and the equilibrium line in terms of the glacial system?

A

glacial mass balance is the total accumulation and ablation of a glacier in a year
the equilibrium line is the point at which losses from ablation are balanced by gains of accumulation in a glacier

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29
Q

What are the components causing a glacier to advance? (accumulation)

A
  • precipitation/snowfall
  • avalanche
  • wind deposition
  • rock debris
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30
Q

What are the components causing a glacier to retreat? (ablation)

A
  • rock debris
  • sublimation/evaporation
  • calving
  • meltwater
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31
Q

What are the two shorter-term climatic events?

A
  • The Loch Lomond Stadial (Pleistocene)

- The Little Ice Age (Holocene)

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32
Q

What was the Loch Lomond Stadial?

A
  • the last glacial advance in the UK, 12,000-10,000 years ago, marking the end of the Pleistocene period
  • characterised by the development of ice caps and cirque glaciers in the Scottish Highlands and a large ice field along the Western Highlands
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33
Q

What was the Little Ice Age?

A
  • cold period between 1300-1870 in which Europe was subject to colder winters (averaging 2 degrees)
  • characterised by the Baltic Sea freezing over, pack ice expanding far south into the Atlantic, widespread crop failure and famine
  • caused by little sunspot coverage and North Atlantic Oscillation (interaction between ocean and atmosphere)
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34
Q

How has glacial distribution changed since the Pleistocene period?

A
  • ice sheets used to reach as far south as the UK, but now only reaches Greenland
  • used to be 2 ice sheets in North America and the Scandinavian Ice Sheet, other extensions include all of SW South America and Siberia
  • at Pleistocene maximum, ice cover was 3x greater than it is today
  • 20% of earth today experiences periglacial conditions compared to 33% in Pleistocene period and at much lower latitudes
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35
Q

What are the 3 factors affecting ice mass distribution?

A
  • latitude
  • altitude
  • aspect
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36
Q

How does latitude affect ice mass distribution?

A

in high latitudes, the sun’s rays hit the ground at a lower angle, so the solar energy received has to heat a larger area - causing lower insolation (so decreased temperature and less melting of glaciers)

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37
Q

How does altitude affect ice mass distribution?

A

high altitudes are implicated by the environmental lapse rate whereby temperature declines by 1 degree every 100m above sea level (particularly affects alpine ice, where as latitude affects polar ice masses)

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38
Q

How does aspect affect ice mass distribution?

A

aspect determines how much ice is falling and where it settles e.g. north/east slopes in the northern hemisphere are more sheltered so have larger ice masses

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39
Q

What is permafrost?

A

permanently frozen ground where sub soil temp remains under zero for at least 2 years

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40
Q

How much of the earth experiences periglacial conditions?

A

20%

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41
Q

What are the different types of permafrost? (with brief description)

A
  • isolated permafrost (covers less than 10% of the landscape)
  • continuous permafrost (found in coldest areas at highest latitudes)
  • discontinuous permafrost (shallow and permanently frozen areas fragmented by patches of unfrozen ground)
  • sporadic permafrost (annual temp averages just below freezing, covers less than 50% of the landscape)
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42
Q

What are the 5 factors affecting distribution of permafrost/periglacial landscapes?

A
  • climate (global factor - temperature determines presence, depth and extent of permafrost)
  • proximity to water bodies (lakes are warmer so remain unfrozen)
  • slope/angle/aspect (influences insolation and therefore melting, freeze-thaw, wind etc)
  • ground surface (rock and soil types)
  • vegetation cover (can insulate the ground)
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43
Q

What are the 6 periglacial processes?

A
  • nivation
  • frost heave
  • freeze-thaw weathering
  • solifluction
  • high winds
  • meltwater erosion
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44
Q

What is freeze-thaw weathering?

A

water freezes in cracks of rocks and expands by 9%, weakening the rock and causing it to break into fragments

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45
Q

What is solifluction?

A

the downslope movement of saturated ground under the influence of gravity

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46
Q

What is nivation?

A

processes such as freeze-thaw, solifluction and meltwater erosion weaken and erode the ground beneath a snow patch

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47
Q

What is frost heave?

A

the ground freezes and large stones are chilled more quickly than soil, water below the stones freezes and expands, pushing the stones upwards and forming small domes on the surface (creates patterned ground)

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48
Q

What is meltwater erosion?

A

thawing in summer creates meltwater, which erodes rivers, refreezing in winter causes a reduction in discharge and sediment deposition in the channel

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49
Q

What are the periglacial landforms?

A
  • ice wedges (and ice wedge polygons)
  • loess
  • patterned ground/stone polygons
  • pingos (open and closed)
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50
Q

How are ice wedges formed?

A

permafrost contracts under low temperatures, causing it to crack - meltwater then enters these cracks, refreezes in the winter, and forces the cracks to widen

  • can extend as far as 10m
  • e.g. Hudson Bay Lowlands
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51
Q

How are loesses formed?

A

aeolian action occurs whereby the wind picks up and transports fine sediment across the surface due to a lack of vegetation, this sediment is then deposited, creating soils of high agricultural potential e.g. Mackenzie Doubter, Canada

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52
Q

How is patterned ground formed?

A
  • frost pushes sediment upwards and outwards to form circles doming from frost heave
  • sediment rolls out to the outside of the pattern under gravity, leaving finer sediment in the middle
  • mass movement can cause stone nets as polygons are elongated
    e. g. North West Canada
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53
Q

How are pingos formed?

A
  • open pingos form when surface water infiltrates into the ground and circulates in sediment before freezing - the water then expands from freezing, forcing overlying sediment upwards into dome shaped features with ice masses underneath
  • closed pingos form when water is trapped under a frozen lake and by the advance of permafrost - the water freezes and expands, forcing the ground above it to rise upwards into a dome
    e. g. Prince Patrick Island, NW Canada
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54
Q

How is ice formed?

A
  1. snow falls and collects, fresh layers of snow fall each day and build up
  2. snow becomes compacted as air gets pressed out and starts freezing together, becoming granular
  3. the granular snow is increasingly compressed to form a névé/firn
  4. as snow layers increase, the process continues and layers become deeper
  5. the névé can then transform into glacier ice
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55
Q

What are the factors affecting accumulation and ablation of glaciers?

A
  • amount of precipitation
  • average temperatures
  • levels of solar insolation
  • levels of wind speeds
  • latitude
  • continentality (proximity to water)
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56
Q

How much of the world’s ice masses are experiencing rising trends in their net negative balance?

A

75%

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57
Q

What are positive and negative feedback cycles?

A
  • a negative feedback cycle is one that is balanced, whereby the glacier minimises the effect of new inputs to regain equilibrium - the input of snowfall would equal the output of snowmelt
  • a positive feedback cycle is not balanced, by amplifying the effects of an input which causes a shift in the system e.g. advancing glaciers leads to more albedo (sunlight reflected) leading to more ice and so glacier continues to advance without being balanced by the output
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58
Q

What is the casestudy involving 1 of the 2 remaining ice sheets?

A

greenland

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59
Q

How much ice does Greenland have stored?

A

2.5 million km3

60
Q

How thick is Greenland’s ice?

A

3km thick in the centre, depressing the crust by 1km in depth

61
Q

What is Greenland’s mass balance?

A

mass balance of the ice sheet has changed recently - negative mass balance: saw a net decline of 329bn tonnes in ice 2018-19

62
Q

Why does Greenland have a negative mass balance?

A

from 2 positive feedback loops

  • ice melts from greenhouse effect - melting reveals bare ground - albedo effect is reduced so land is warmed - less reflection of solar radiation - increase in global warming
  • ice melts from greenhouse effect - melting reveals bare ground - methane is released into atmosphere - increase in global warming
63
Q

What are the characteristics of warm based glaciers?

A
  • occur in high altitude areas outside of polar regions e.g. Alps
  • ice temperature often close to zero
  • summer temperatures cause melting
64
Q

What are the characteristics of cold based glaciers?

A
  • occur in polar regions in high latitude areas e.g. Greenland
  • frozen into bedrock below
  • melting occurs only on the surfacein the summer months
65
Q

What is the pressure melting point?

A
  • the temperature at which the ice begins to melt, which is lower within the glacier due to pressure (e.g. at the base of a glacier ice will melt below 0°C, allowing it to move with help of meltwater even if air temp is below freezing point) - only impacts warm based glaciers
66
Q

How do cold based glaciers move?

A
  • internal deformation
67
Q

How does internal deformation cause cold based glaciers to move?

A
  • the weight of glacier ice and gravity causes ice crystals within the glacier to deform, causing it to move downslope slowly - this movement can be inter-granular (individual crystals slide over eachother) or intra-granular (crystals deform due to stress in ice, moving downhill due to gravity)
  • cold based glaciers are too cold to be affected by PMP so can only move under this process
68
Q

How do warm based glaciers move?

A
  • basal slip
  • creep and regelation
  • extending and compressing flows
  • surges
69
Q

How does basal slip cause a glacier to move?

A
  • base of the glacier is at the PMP, meaning meltwater is present and acts as a lubricant, allowing the glacier to slide over bedrock
70
Q

How does creep and regelation cause a glacier to move?

A
  • large obstacles on valley floor (1m+ wide) cause an increase in pressure, meaning the ice plastically deforms around the feature (known as creep)
  • smaller obstacles (less than 1m wide) cause pressure melting, increasing basal slip, the ice then refreezes (regelation) on the downglacier/lee side of the obstacle
71
Q

How do extending and compressing flows cause a glacier to move?

A
  • basal slip increases on steep slopes, and the ice will accelerate and thin (extending flow)
  • over shallow slopes, basal slip slows and the ice decelerates and thickens (compressing flow)
72
Q

How do surges cause a glacier to move?

A
  • short-lived event in which a glacier advances substantially, up to 100x faster than normal
  • triggered by causes e.g. earthquakes and is enhanced by basal sliding from meltwater building up at the ice-rock interface
73
Q

What are the 6 factors affecting the movement/speed of a glacier?

A
  • altitude (affects precipitation and temp, ie more precipitation and lower temp increase supply of ice and so its mass balance)
  • gravity/slope gradient (steeper the gradient the faster it flows)
  • ice mass/thickness (heavier glaciers have greater pressure in the ice so pmp more affected)
  • rock type (permeable rocks percolate meltwater, slowing movement of the glacier)
  • ice temperature (colder ice doesn’t deform as easily and stays stuck to bedrock)
  • meltwater (more meltwater means more basal slippage so faster movement)
74
Q

What are the glacial erosional processes?

A
  • abrasion
  • plucking/quarrying
  • crushing
  • basal melting
75
Q

What is glacial abrasion?

A
  • angular material in the ice scours the landscape, this includes large rocks that scratch the bedrock to form striations, and rock flour (under 0.1mm) that polished underlying rocks in “sand paper” action
76
Q

What is glacial plucking/quarrying?

A
  • basal meltwater enters cracks in rocks, surrounding the rock and freezing onto it, then as the glacier moves, it pulls the rock, causing it to fracture and thus it is “plucked” from its position
    (only occurs where rocks in the glacier have experienced freeze/thaw)
77
Q

What is glacial crushing?

A

direct fracturing of weak bedrock by the weight of the glacier above it, producing large angular blocks of rock (the bedrock must therefore be weakened prior, either by freeze-thaw weathering or dilation from repeated glacier advance and retreat)

78
Q

What is the greatest recorded thickness of ice?

A

4780m in Antarctica

79
Q

What are the factors that alter the glacial landscape?

A
  • erosion
  • entrainment
  • transport
  • deposition
80
Q

How does erosion alter glacial landscapes?

A
  • weathering of the valley through processes e.g. freeze-thaw weakens the rock
  • this allows the moving glacier to erode/remove rock debris, thus altering the landscape
  • erosional processes include: abrasion, plucking/quarrying, crushing and basal melting (as mentioned previously)
81
Q

How does entrainment alter glacial landscapes?

A

entrainment - process of surface sediment being incorporated into a fluid flow
- this occurs as part of the process of erosion

82
Q

How does transport alter glacial landscapes?

A
  • supraglacial transport: material carried on top of the ice (incl. material from hillsides, volcanic ash etc)
  • englacial transport: supraglacial material that is now buried/carried within the ice
  • subglacial transport: material carried below the ice (incl. material eroded from the bedrock, valley walls, and englacial material that has sunk to the bottom)
83
Q

How does deposition alter glacial landscapes?

A
  • sediment is deposited as the glacier melts (mainly in ablation zone close to the snout)
  • the sediment melts out, the water may then carry it further from the ice often over many km
84
Q

What are cirques/corries/cwms?

A

large rounded hollow high on the mountain side, formed on north facing slopes on mountains in northern hemisphere

85
Q

How do cirques form?

A
  • depression exists on the side of a mountain
  • snow collects in the hollow, and is compressed to form a névé, then glacier ice
  • abrasion, plucking and freeze-thaw makes the hollow bigger
  • gravity encourages a circular motion (rotational slip) of the ice within the hollow, causing it to pull away from the back wall, creating a bergschrund
  • plucked debris from the back wall causes further erosion, deepening the cirque
86
Q

What is an example of a cirque?

A

Red Tarn, Lake District

87
Q

How do arêtes form?

A
  • arêtes are the sharp/narrow ridges between two cirques (that erode backwards towards one another)
88
Q

What is an example of an arête?

A

Striding Edge, Lake District

89
Q

How do pyramidal peaks form?

A
  • a pointed mountain peak between 3+ cirques (that erode backwards towards eachother)
90
Q

What is an example of a pyramidal peak?

A

Matterhorn, the Alps

91
Q

How do glacial troughs/U-shaped valleys form?

A
  • a v-shaped river valley is widened/deepened from plucking and abrasion from a valley glacier, to form a U-shaped valley with steep sides and a wide, flat floor
92
Q

How do truncated spurs form?

A
  • valley glaciers are less flexible than rivers so remove ends of interlocking spurs (through plucking/abrasion), forming steep valley sides where spurs once interlocked
93
Q

How do hanging valleys form?

A
  • U-shaped valleys high above the main glacier floor
  • this occurs as thicker ice in the main floor eroded vertically downwards, more rapidly than the thinner ice in tributary valleys, thus leaving floors of tributary valleys high above the main valley floor
94
Q

What is an example of a hanging valley?

A

Cairngorms

95
Q

How are ribbon lakes formed?

A
  • a valley glacier causes plucking and abrasion that deepens part of the valley floor, forming a long narrow lake along the floor of a glacial trough
96
Q

How do roche moutonnées form?

A
  • outcrop of more resistant rock raises creep and regelation around it
  • as ice slides over the rock it scours and smooths the upside of the valley (stoss)
  • refreezing on the other side causes plucking of the downside (lee) causing smooth stoss and jagged lee
97
Q

What is an example of a roche moutonnée?

A

Snowdonia

98
Q

How do knock and lochans form?

A
  • scouring at the base of a glacier excavates areas of weaker rock, forming hollows that fill with meltwater/precipitation following glacier retreat
  • lowland areas of small rock hills (knock) and hollows (lochan) are therefore created
99
Q

What is an example of knock and lochan?

A

Cairngorms

100
Q

How does crag and tail form?

A
  • a mass of hard rock is resistant to ice scouring and creates a steep stoss (valley upside), reduced glacier velocity on the lee (downside) protects the softer rock and allows deposition, but the sheltering effect diminishes with distance, creating a sloping tail
101
Q

What is an example of a crag and tail?

A

Edinburgh

102
Q

What are the different sizes of glacial landforms?

A
  • macro-scale: landforms 1km or more, forming major elements in the glaciated landscape e.g. arete
  • meso-scale: landforms largely found within macro features e.g. roche moutinnee
  • micro-scale: landforms less than 1m long e.g. striations, moraine
103
Q

What are the types of glaciated landscapes?

A
  • upland (high altitude)
  • lowland (low altitude)
  • active (currently experiencing glaciation with active processes/landform development)
  • relict (not currently characterised by glaciers but have fossilised glaciated landforms from past glaciation)
104
Q

What is till?

A

material deposited under the ice - can be transported long distances

105
Q

What are erratics?

A

till that has been transported and deposited in areas of different geology - can be carried 300km and weigh up to 16,000 tonnes e.g. from Canadian Rockies to plains of Alberta

106
Q

What is moraine?

A

accumulation of till into a glacial landform

107
Q

What are the types of moraine and what are they?

A
  • lateral moraine (high, symmetrical ridge along outer edge of a glacier from freeze-thaw on valley sides that cause material to fall onto edge of glacier below)
  • medial moraine (lateral moraines from 2 merging glaciers join up, leaving behind line of debris in the centre, and as the glaciers melt, the medial moraine is deposited to form a low ridge)
  • terminal moraine (ridge of sediment accumulates at furthest extent of an advancing glacier, can appear as line of hills due to erosive action of meltwater)
  • recessional moraine (retreating glaciers experience periods of stability when a secondary ridge of sediment forms at the snout)
108
Q

What are drumlins?

A
  • oval/egg-shaped hills made of till and aligned in the direction of ice flow - usually around 500m long, and occur in ‘swarms’ on valley floors, forming a ‘basket of eggs’ topography
109
Q

How are drumlins formed?

A
  • sediment is deposited and the glacier moves over it, creating a smooth slope on one side and PMP occurs, making a jagged end
110
Q

How are till plains formed?

A

large section of ice detaches from the glacier body and melts, suspended debris is deposited to form a large plain of unsorted till

111
Q

What is lodgement till?

A
  • subglacial debris that is being transported under a glacier becomes lodged in the glacier bed (due to friction between the debris and bed becoming greater than the drag of ice above, often in slow moving glaciers)
112
Q

What is ablation till?

A
  • any debris that is dumped as glacier melts
113
Q

What is a till fabric analysis?

A

the study of orientation and dip of particles in till deposits, involved: measurement of sediment size, roundness, and orientation
- presented in rose diagram

114
Q

What us a glacial outburst?

A

glacial meltwater behaves like a river, and if it becomes trapped (either beneath ice or as surface lakes), it may burst - the surging meltwater has the power to carve deep channels/gorges e.g. Glacial outburst flood in Nepal 2012

115
Q

How do meltwater channels move?

A
  • travels in supraglacial, englacial and subglacial channels
  • supraglacial water forms from ice melt in summer, flows off glacier and creates cracks
  • glacier ice is permeable but water percolates at a slow rate so is generally considered impermeable
  • pressure of structures within ice allow water to penetrate into ice
  • geothermal heating causes basal melting - basal meltwater flows through subglacial networks
  • saturated neves become ‘swamp zones’
116
Q

What are the types of fluvio-glacial landforms?

A
  • ice contact features (on/within/in contact with ice)

- pro-glacial features (‘in front of’ or immediately beyond glacier margin)

117
Q

What are the different ice-contact features?

A
  • kame
  • kame terrace
  • esker
118
Q

How are kames formed?

A

meltwater streams emerge onto the valley at the glacier snout - velocity of stream drops, depositing mound of fluvio-glacial sediment (kame)

119
Q

How are kame terraces formed?

A

melting at the glacier edge during summer creates meltwater streams that deposit sediment, as glacier retreats, sediment falls to valley floor, forming flat, linear deposit of fluvio-glacial sediment (kame terrace)

120
Q

How are eskers formed?

A

subglacial streams with high hydrostatic pressure carry dense amount of sediment and when the glacier retreats this is deposited at a consistent rate forming long, narrow, sinuous ridge (esker)

121
Q

What are the proglacial features?

A
  • sandur/outwash plain
  • kettle hole
  • proglacial lake
  • meltwater channel
122
Q

How are sandurs formed?

A
  • meltwater streams emerge from glacier and enter lowland areas, gradually losing energy and depositing debris, with coarse gravels deposited in front of the snout, followed by sands, then clay (furthest away from glacier)
123
Q

How are kettle holes formed?

A

glacier retreats and blocks of ice detach from it and remain in place, meltwater then flows over the blocks and covers them in sediment. the ice blocks eventually melt and the sediment subsides to create circular depressions that often fill with water

124
Q

How are proglacial lakes formed?

A

lakes formed from the damming action of terminal/recessional moraine during glacial retreat, or by hills/ice sheet blocking the escape of meltwater

125
Q

How are meltwater channels formed?

A

meltwater erodes deep channels from hydrostatic pressure in the glacier coupled with high sediment load - this pressure allows channels to flow uphill

126
Q

What’s the difference in characteristics between glacial till and fluvio-glacial deposits?

A

in fluvio-glacial debris:

  • rounder/smoother (from attrition, where as till is frozen into ice so shape remains angular)
  • aligned in the direction of the flow and dip upstream (till also aligned in this direction but often horizontally rather than dipping)
  • stratified vertically with distinctive layers reflecting seasonal/annual sediment accumulation (where as till is unsorted and unstratified)
  • sorted horizontally into layers of consistent size (where as till is unsorted as ice had power to transport all sizes)
127
Q

What are the environmental values of glaciated landscapes?

A
  • water cycling
  • climate control
  • carbon cycling
  • weather system control
  • fragile ecosystems
  • carbon sequestration (storage)
  • genetic diversity
128
Q

What are the cultural values of glaciated landscapes?

A
  • spiritual/religious inspiration
  • leisure/recreation e.g. skiing
  • native people with distinct cultures
  • scientific research e.g. ice core analysis
129
Q

How is the Yamal peninsula valuable?

A
  • environmentally: home for migratory species so role in worldwide food web, permafrost acts as carbon store
  • culturally: native Nenets live sustainably with 300,000 reindeer providing transport/clothing/meat/income, migrate seasonally
  • economic value: herder economy driven by reindeer meat, supporting 10,000 nomads, 80% of peninsula owned by herders - however doesnt compete with value of natural resources: contains 1/4 of the worlds known gas reserves
130
Q

How is the Yamal peninsula threatened?

A
  • climate change: earlier spring melts, later freezes affect ability to cross the landscape, large sinkholes discovered potentially from methane as permafrost thawed
  • 1980s infrastructure to exploit Bovanenkovo gas field destroyed pasture, forcing overgrazing of tundra and disrupted migration routes, not environmental impact assessment
  • ‘yamal megaproject’ whereby state-owned Gazprom aims to exploit vast gas reserves on the peninsula - incl construction of railway, pipeline, bridges - already evicted 160 herders, Gazprom says it plans to build housing, kindergartens, hospitals etc which threatens traditional culture
131
Q

In what ways is Svalbard a valuable glaciated landscape?

A
  • home to 3,000 people
  • Svalbard Environmental Protection Act 2002 protected cultural heritage and environment of Svalbard (cultural importance)
  • 60% ice cover with 2,000 glaciers, permafrost common (so important carbon store)
  • 10% of landscape is vegetated, 3500 polar bears (ecologically important)
  • home to many research stations with current research involving atmospheric changes linked to climate change
  • new airport in Longyearbyen increased tourism
  • 700,000 visitors in 2013
  • mining industry thrives under Norweigan state-owned company, employing 1/3 of all Svalbard’s workers (economically important)
132
Q

How is Greenland valuable/threatened?

A
  • 10% of global ice mass (important in global water cycle) - threatened as average rate of ice loss increased 34 gigatonnes (1992-2001) to 215 gigatonnes (2002-2011)
  • contributed to 0.33mm sea level rise (2002-2011)
  • regulates global climate through feedback cycles: ice has high albedo so reflects more solar radiation (reduction in surface means more is absorbed - positive feedback)
  • Greenland Inuit: many now live in modern homes with appliances as part of mining industry, but some retain traditional fishing cultures
  • drilling deep ice cores allow for unique look at climate in the past
  • HEP potential, ice retreat reveals valuable fossil fuels
133
Q

What are the economic activities that take place in glaciated landscapes?

A
  • farming (indigenous communities rely on subsistence farming e.g. Bolivia- 70% live in Andes growing beans, alpacas etc but only earn 30% of GDP, developed countries use Alpine areas for pastoral farming)
  • tourism (year-round activities e.g. walking, skiing, increased communications means more remote areas affected e.g. Arctic - Greenland seen increase in cruise liners)
  • forestry (difficulty to use upland areas for other means so forestry prevails e.g. Forestry Commission in UK with mainly non-native coniferous trees)
  • mining (glacial erosion exposes valuable rocks e.g. rubies in Greenland, outwash deposits provide sand for building industry
  • HEP (Norway and NZ derive 90% of electricity from this using natural ribbon lakes and reservoirs - potential to revolutionise developing countries)
134
Q

What are the limiting factors of vegetation growth in periglacial environments?

A
  • soil thinness
  • lack of sunlight
  • high winds
  • low temperature
135
Q

What are the characteristics of vegetation in periglacial areas?

A
  • only occurs in areas not covered in ice
  • lower arctic latitudes have higher carrying capacity (can support more): continuous cover of ground vegetation incl mosses, dwarf trees, heaths/grasses
  • higher arctic latitudes/altitudes have lower carrying capacity (can support less): polar desert conditions allow just a small range of plants in sheltered locations e.g. arctic poppy and purple saxifrage (heads of flowers follow sun, cushion shape, with deep roots)
  • in summer, surface permafrost melts to form shallow lakes, attracting insects and so migrating birds, in winter plants (which animals rely on) must survive under the snow
136
Q

What is the tundra’s role in the water cycle?

A
  • water cycle is maintained through water storage (75% of freshwater stored in ice, glaciers contain 2% of all water)
  • meltwater is water source for settlements, creating storage in lakes/rivers e.g. Alps transport 216km3 of water a year
137
Q

What is the tundra’s role in the carbon cycle?

A
  • maintained by the tundra as permafrost/peat act as carbon stores - 14% of carbon in permafrost
  • arctic amplification - permafrost melts and increases greenhouse gases (positive feedback loop)
  • Arctic is currently a carbon sink (absorbs more than it releases) however this could change with climate change
  • some think as permafrost thaws, carbon will remain in soil for vegetation use (negative feedback loop) - others believe in arctic amplification
138
Q

What are the natural threats to glaciated landscapes?

A
  • avalanches (sheer stress exceeds sheer strength of snow on a slope, killing approx. 200 people per year mostly in the Alps or Rockies, however follow known tracks and can be predicted)
  • glacial outburst floods (potential for this where meltwater collects behind ice/moraine, large floods that present huge threat to people/property e.g. in Iceland)
  • rock fall
  • debris slides
139
Q

What are the human threats to glaciated landscapes?

A
  • tourism/leisure (resorts in glaciated areas e.g. Zermatt in Switzerland attracts 2 million visitors a year, creating huge demand for resources, pollution etc)
  • dam/reservoir construction (glaciers store 75% of fresh water, Tibetan Plateau has 37,000 glacietsm creating many rivers e.g. Ganges: 2 billion rely on ice fed rivers, China aims to build 59 reservoirs requiring intense heavy machinery)
  • deforestation/urbanisation (settlements predominantly built for resource exploitation e.g. in Yamal peninsula, threatens natives)
140
Q

How is Sagarmatha National Park, Nepal threatened by humans?

A
  • deforestation for farmland, firewood, infrastructure, means only 30% of Nepalese forests remain
  • tourism in the hands of 6,000 Sherpa people - boosting local economy - but led to environmental and socioeconomic change e.g. footpath erosion, water pollution, demand for waste disposal, hotels, changes to Sherpa way of life
141
Q

How is the Lake District threatened by humans?

A
  • walkers destroy vegetation and compact soil, reducing infiltration rates, exposed soil is easily washed away
  • avoidance of eroded footpaths makes bigger problem
  • increased storms worsen issue
  • 2014, visitors spent £1.1 billion supporting local economy, tourism provides 16,000 jobs in Park and money for environmental protection
142
Q

What are the impacts of global warming on cold environments?

A
  • melting of permafrost
  • loss of biodiversity
  • glacial retreat
  • increased glacial outburst floods
143
Q

How has global warming impacted glaciers (examples)?

A
  • majority of glaciers now in retreat
  • on Rocky mountain eastern slopes, glaciers have lost 25-75% of mass since 1850
  • 85% of Himalayan glaciers in rapid retreat
  • Okjokull glacier died in 2014 when it was no longer thick enough to move - mourned in Iceland
144
Q

How will retreating glaciers (from climate change) impact the hydrological cycle?

A
  • affects amount of water available - receding glaciers produce more meltwater and glaciers often feed rivers e.g. Ganges from Himalayas - therefore increased meltwater means steady loss of future supply - huge implications e.g. reduction of meltwater into the Indian Ganes-Brahmaputra system means 500 million will face water shortages and 40% of India’s irrigated land will be affected
  • affects quality of water - during summer months, when glacial ablation his highest, discharge will increase, also increasing sediment yield, meaning water would become increasingly cloudy and sediment-laden, affecting water quality
145
Q

What are the stakeholders for glaciated landscapes?

A
  • IGOs (promote international cooperation incl protection of natural environment to achieve global sustainability e.g. Antarctica protected under treaty of 1959)
  • TNCs (use economic resources to maximise profits e.g. Exxonmobil)
  • Pressure groups (influence public policy e.g. Greenpeace aims protect landscape from exploitation, ANWR campaigns in favour of oil exploitation)
  • National/local gov (management strategies to balance needs of stakeholders)
  • local businesses (use local resources to maintain livelihood)
  • natives (depend on natural environment for survival, spiritual, cultural links to physical environment e.g. Inuit)
  • tourists (require infrastructure to enjoy scenery, strong aesthetic value from environment)
146
Q

What are the different management approaches for glaciated areas?

A
  • total exploitation (maximum economic exploitation without protection of environment e.g. Russian gov may favour total exploitation of Yamal peninsula for gas)
  • sustainable exploitation (aims for a balance between economic needs and conservation needs, takes all stakeholders interests into account to reduce conflict e.g. Alpine Convention aims to manage European Alps
  • total exploitation (to completely conserve natural environment, exploitation limited to scientific research and eco-tourism, often only feasible in remote areas e.g. Antarctica, enforced by legal frames e.g. Antarctica Treaty 1959)

Geography 1 (4 decks)

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