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glaciers Flashcards

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1
Q

how is a glacier formed?

A

summer melts -> snowflake falls -> melting, evaporation and compaction -> over hundreds of years a névé forms (compacted snow)

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2
Q

how does a glacier decline?

A

temperature rises -> snow melts -> decrease in albedo -> more heat absorbed

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3
Q

glacial inputs

A

ice, snow, avalanches, rocks, rain

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4
Q

glacial outputs

A

meltwater, moraine and till, sublimation

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5
Q

how do glaciers balance energy?

A

enters through solar and infrared radiation -> reflected through albedo or absorbed into the glacier -> surplus energy melts snow and ice

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6
Q

what is the positive feedback loop?

A

decrease in temperature -> increase in ice -> increase in albedo -> increase in solar radiation reflected-> decrease in radiation absorbed

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7
Q

what is the negative feedback loop?

A

temperature increases -> ice melts -> less albedo -> more radiation absorbed

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8
Q

when was the last glacial period?

A

started 115,000 years ago
ended 11,700 years ago
large ice sheet over N.America, asia, europe
glaciers formed in greenland and canada

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9
Q

characteristics of a polar environment

A

-large snowy areas
-small amount of precipitation
-large expanses of sea ice
-temperatures below -50
-e.g. Antarctica

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10
Q

characteristics of a glacial environment

A

-mountainous regions
-heavy snow in winter
-ice is the main transport process
-warm summers promote meltwater
-e.g. Greenland

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11
Q

characteristics of a periglacial environment

A

-on the edge of glacial and polar regions
-presence of permafrost
-short summers allow small amounts of surface thaw
-Canada, Russia, Greenland

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12
Q

characteristics of an alpine environment

A

-temperature below 10
- heavy snow in winter
-high altitude
-summer temperatures above 15
-e.g. Alps

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13
Q

what is the antarctic climate?

A

-sunlight hits the surface at a low angle
-has a lower temperature due to being surrounded by sea
-dark winters and light summers
-regular storms

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14
Q

what is the arctic climate?

A

-sunlight hits the surface at a low angle
-dark winters and light summers
-has a higher temperature due to being surrounded by land
-warm ocean currents bring warm moist air

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15
Q

glacial mass balance

A

positive mass balance in winter as more accumulation
negative mass balance in summer as more ablation

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16
Q

what is the vegetation in the tundra?

A

-few trees and low bushy vegetation
-lichen on rocks
-mosses and dwarf shrubs
-freeze thaw in summer

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17
Q

what is the vegetation in the tundra?

A

-few trees so low bushy vegetation
-lichen found on rocks
-mosses and dwarf shrubs
-freeze thaw in summer

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18
Q

what is the vegetation in permafrost?

A

-topsoil can be -30 in winter
-ice lenses
-pingos
-topsoil is 10 in summer

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19
Q

what is the vegetation in the arctic?

A

-1700 species of plant
-shallow rooted plants

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20
Q

what is the vegetation in the antarctic?

A

-500 species of plant
-mosses and lichen

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21
Q

what is the vegetation in cold environments?

A

-shallow roots
-perennials (no seeds)
-asexual reproduction
-grow in groups
-can photosynthesise in low temperature
-small leaves

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22
Q

what is the biosphere?

A

the region on, above and below the earths surface where life exists

23
Q

what is the atmosphere?

A

a mixture of gases that surrounds earth

24
Q

what is the geosphere?

A

the rocks, minerals and landforms of the surface and interior of earth

25
Q

define cryohydration

A

individual particles in the soil are split as a result of freezing and contracting of water on the surface of the mineral particle

26
Q

what is permafrost?

A

-remains frozen all year round for atleast two consecutive years
-found in high altitudes or latitudes
-active layer of soil on top (30-200cm)
-permafrost is up to 1500m thick
-permafrost is in 25% of land in the northern hemisphere
-decomposed plant and animal matter is trapped in the permafrost so when it melts it releases co2 and methane

27
Q

what are periglacial areas?

A

-intense frost action
-development of permafrost
-tundra of N.Russia, Alaska and N.Canada
-some areas of the alps

28
Q

cold based (polar) glaciers

A

-glacier is frozen to the bedrock
-very little ice movement
-internal deformation occurs -> the ice crystals slide on top of eachother in the glacier
-e.g. antarctica and greenland

29
Q

warm based (temperate) glaciers

A

-meltwater under the glacier
-20-200m per year of movement
-basal sliding and internal deformation occurs
-e.g. alps and alaska

30
Q

what is internal deformation?

A

1) jumble of ice crystals
2) when under pressure the ice crystals align
3) the ice crystals can now slide over one another

31
Q

what is basal sliding?

A

-pressure between ice and an obstacle
-pressure causes melting
-water flows around and refreezes
-occurs on temperate or warm based glaciers

32
Q

rate of movement

A

-gravity- gradient steeper = more nonevent
- ice temp - warmer = more movement
-meltwater - more meltwater = more movement
-ice mass - heavier = more movement

33
Q

what happens when there is a steep gradient?

A

-glacier is fast moving
- thinner glacier
-crevasses form
-seracs form
-extensional flow

34
Q

what happens when there is a shallow gradient?

A

-the glacier is slow moving
-thicker glacier
-crevasses close
-compressional flow

35
Q

formation of scree

A

-frost shattering occurs
-scree gathers at the bottom of the slope
-happens in steep areas

36
Q

formation of a nunatak

A

-exposed summit of a ridge
-undergo heavy frost shattering due to proximity to ice
-located within an ice field or glacier

37
Q

what is solifluction?

A
  • a name for the gradual processes when a mass moves down a slope due to freeze thaw activity
  • for example the movement of a temperate glacier
38
Q

what is frost heave?

A

1) active layer refreezes
2) the soil directly beneath a stone freezes and expands which pushes it to the surface
3) stones roll downhill - sorts the material - forms patterned ground

39
Q

formation of ice wedges

A

-refreezing the active layer causes soil to contract
-cracks open during the summer melts
-meltwater enters the cracks
-can be 1m wide and 2-3m deep
-cycle repeats every year

40
Q

formation of pingos

A

-domed shaped hills
-closed and open systems
-500m diameter and 50m high
-caused by seasonally changing active layer

41
Q

formation of closed system pingos

A

1) frozen lake with sediment on the floor insulates the ground from the cold, allowing talik to exist
2) permafrost advances from below, allowing water to turn to ice
3) pressure increases and sediment is pushed up, creating a mound
4) ice core melts during summer - centre caves in - creates a dip

42
Q

what is plucking?

A

when a glacier freezes the substrate beneath it, as gravity continues to drive the glacier downslope it rips the substrate that it has frozen and transports its downstream

43
Q

what is abrasion?

A

rocks and sediment stuck in the base of the glacier are dragged over the underlying bedrock and wears it away. this is often shown by striations and polished surfaces

44
Q

what is freeze thaw weathering?

A

water fills the crack in a rock - it freezes - the ice expands - widens the crack which breaks pieces of rock of - often occurs on the back wall of a corrie, causes rocks to accumulate on the glacier

45
Q

formation of a corrie

A

-snow accumulates in a hollow and is then compacted and the air is squeezed out which forms ice
-plucking and freeze thaw steepen the back wall
-the base becomes deeper due to abrasion
-a rock lip forms
-moraine adds to a rock lip, creating a tarn

46
Q

formation of a ribbon lake

A

-glacier moves over alternate bands of hard and soft bedrock
-sharp edged boulders carried at the base erode softer rock by abrasion
-a rock basin is formed
-harder rock around the edge erode less
-rock bars form, acting as a dam
-rainwater fills the rock basin
-a ribbon lake forms

47
Q

formation of a hanging valley

A

-form where two glacial valleys meet
-tributary valley glacier is smaller with less mass - valley is eroded less
-main valley glacier is larger with a greater mass - valley is eroded more
-tributary halley is left hanging above main valley
-waterfall flows over the edge of

48
Q

formation of a roche moutonnee

A

-glacier meets resistant rock
-ice advances over the rock
-smooth slope is created through abrasion
-ice flows down over the rock
-plucking removes fragments
-a jagged, rough tail is left behind

49
Q

formation of a truncated spur

A

1)interlocking spurs are left behind form a river
2) abrasion and plucking erodes the tips of the spurs
3) steep cliff like outcrops are left

50
Q

formation of a fjord

A
  • found in locations where glacial erosion happened below sea level
    -when the glacier retreats, sea water fills the valley floor
51
Q

formation of an arête

A

-corries erode backwards through plucking and abrasion
-back walls become steeper
-a steel knife centred ridge is left behind

52
Q

formation of a pyramidal peak

A

-three corries and arêtes meet
-glaciers carve away the top of the mountains
-an angular, sharply pointed summit remains

53
Q

formation of a u-shaped valley

A

-corrie glacier leaves source region and descends down old river valley
-scouring occurs as the glacier moves
-a deep, wide, u-shaped valley is left behind

54
Q

formation of a u-shaped valley

A

-corrie glacier leaves source region and descends down old river valley
-scouring occurs as the glacier moves
-a deep, wide, u-shaped valley is left behind

geography (2 decks)

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