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Geography > Glaciation > Flashcards

Glaciation Flashcards

1
Q

Holocene epoch

A

last 11,700 years

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2
Q

the Pleistocene epoch

A

from 11,700 year to 1.8 million years bp

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3
Q

define eccentricity

A

earths orbit moving from more elliptical to circular over 100,000 years changing the amount of solar radiation received by the sun considering the dominant factor

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4
Q

define obliquity

A

tilt of the earths axis varies from 21.8° to 24.2° and back again over 41,000 years changing the intensity of sun radiation received at the poles so the greater the tilt, the greater the difference between summer and winter

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5
Q

define precession

A

the earth wobbles on its axis over 21,000 years causing long-term changes to when different seasons occur along the earths orbit

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6
Q

what is stadial

A

short sharp drop in global temperates where glaciers re-advance

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7
Q

what is interstadial

A

a short sharp increase in global temperatures where glaciers retreat

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8
Q

define temperate glaciers

A

in high altitude areas outside polar regions, water can exist as a liquid below 0, preventing the glacier from freezing to its bed having lots of debris in the basal layer

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9
Q

define polar glacier

A

occur in high latitudes, particularly in Antartica and Greenland. the glacier remains frozen at the base

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10
Q

difference between continuous, discontinuous and sporadic permafrost

A

-continuous permafrost is in the coldest parts of the world and can extend downwards hundreds of metres. —-discontinuous is more fragmented and thinner.
-sporadic occurs at margins of periglacial environments and is usually very fragmented and only a few metres thick.
-the biggest difference between them all is their depth as they range from hundreds of metres to a few metres

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11
Q

nivation

A

the combination of freeze-thaw and meltwater erosion

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12
Q

frost heave

A

the concentration and cracking of rapidly freezing soils

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13
Q

suction

A

the migration of sub-surface water to the ‘freezing front’

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14
Q

solifluction

A

the mass movement of the active layer downslope

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15
Q

freeze-thaw

A

the 9% expansion of water upon freezing

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16
Q

associated landform of wind erosion

A

loess

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17
Q

associated landform of solifluction

A

solifluction lobes

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18
Q

associated landform of nivation

A

nivation hollow

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19
Q

associated landform of freeze-thaw

A

block fields, scree

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20
Q

associated landform of frost heave

A

ice wedges, patterned ground, pingos

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21
Q

associated landform of suction

A

ice lenses, pingos

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22
Q

external factors that influence rate of accumulation and ablation

A

temperature, precipitation type and amount, latitude and altitude

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23
Q

what factors influence glacier movement

A

friction, temperature, gradient and underlying rock

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24
Q

glacial erosional processes

A

abrasion- where rocks and stones become embedded and are then rubbed against the bedrock and rock faces as the glacier moves
plucking- where rocks and stones become frozen to the base or sides of the glacier and are then tears rocks away as the glacier moves leaving a jagged landscape.

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25
Q

associated glacial erosion processes

A

freeze-thaw and meltwater

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26
Q

four different glacial landform environments

A

periglacial, glacial, marginal and proglacial

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27
Q

what is a rouche moutonnees

A

a small bare outcrop of rock shaped by glacial erosion, with one side smooth and gently sloping(abrasion upslope) and the other steep, rough, and irregular(plucking downslope).

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28
Q

landforms of cirque glacier

A

cirques, aretes, pyramidal peak

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29
Q

landforms of valley glaciers

A

u-shaped valleys, truncated spurs, hanging valleys, ribbon lakes

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30
Q

landforms of ice sheet scouring

A

basins, knock & lochans, roche moutonnees

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31
Q

how does a cirque form

A

snow and ice accumulate in a nivation hollow where nivation processes enlarge and deepen it
as more ice accumulates over time it compacts into glacier ice and begins to flow- a cirque glacier is formed

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32
Q

what happens during a cirque

A

freeze-thaw weathering loosens material which is entrained and gathers and sub-glacial basal ice.
the rotational flow of the glacier deepens the hollow through abrasion
whilst plucking of the back wall erodes the cirque backwards, creating a steep, arm-chair shaped hollow. deposition can take place where flow is weakest and a lip can form on the edge of the cirque

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33
Q

how are basins created

A

created where large ice sheets take advantage of differential rates of erosion of rock, deeply eroding the weaker rock to create basins which are subsequently filled by water

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34
Q

how is knock and lochan created

A

topology occurs as the ice sheet advances it preferentially erodes through the ice sheet, scouring areas of dense jointing more than areas without joining

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35
Q

The 2 glacial deposition processes

A

Lodgement and ablation

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36
Q

Define lodgement

A

Beneath the ice mass, subglacial debris being carried,become lodged, occurs when friction is greater than drag force

37
Q

Define ablation

A

Material is deposited as the glacier melts

38
Q

Upland landforms and characteristics

A

Moraines- large glacial deposits.
Drumlin-oval or egg shaped hill

39
Q

Low land landforms and characteristics

A

Erratics - boulders picked up by ice and deposited
Till plains- an extensive plain

40
Q

What is supragcacial hydrology

A

Water on glacier formed by ice melting in summer
Flows off, into a number of cracks similar to ordinary river system.

41
Q

What is englacial hydrology

A

Structures in the ice (crevasses), allow water to penetrate in ice

42
Q

Characteristics of fluvioglacial deposits

A

Smaller, more rounded, sorted horizontally, stratified vertically

43
Q

What are kames and kames terraces and how are they formed

A

K- Material collects within a depression When the glacier melts completely, the material is left on the valley floor. This leaves a mound fine material

Kt-during the summer, meltwater streams are formed at the side of the glacier, which deposit material. a flat, linear deposit of sediment at valley sides

44
Q

Values of glaciated landscapes

A

Cultural, economic, environmental, biodiversity, natural systems

45
Q

2 example environmental values

A

Maintain a gene pool of wild organisms to ensure genetic variety
Arctic and Antarctic environments are living labs

46
Q

2 example economic values

A

Farming, tourism

47
Q

2 biodiversity values

A

Tundra covers 8 million km 2
Permafrost increases fragility

48
Q

how do glaciated landscapes maintain natural systems

A

75% of all freshwater is locked up as ice
the UN estimates that 40% of the global population could be affected by the changes to meltwater regimes in Asia
Permafrost may currently hold 1500 billion tones of carbon

49
Q

3 natural threats

A

Lahars, glacial outburst, avalanches

50
Q

What is a glacial outburst

A

A powerful flood, resulting from a bursting subglacial lake

51
Q

How does tourism affect active temperate environments

A

Both winter and summer sports put pressure on the environment in the form of various types of pollution, though most resorts attempt to minimise the impacts through renewable energy and recycling.

52
Q

Human activity threats to upland active and relict landscapes

A

Resource exploitation- oil in Alaska
Tourism- footpath erosion
Climate Change

53
Q

Environmental impacts of human activities

A

Soil erosion (r)
Changes to hydrological cycle (a)
Thawing permafrost (a)
Invasion of species due to warming(a)

54
Q

Economic impacts of the environmental consequences

A

Decline in agriculture productivity
Decline in tourism as a result of environmental degradation
Decline in tourism from warming
Increased energy insecurity

55
Q

Who are the players in management approaches

A

Local government
National government
Conservationists
NGOs
International organisations
Local people

56
Q

Describe do nothing on the spectrum of management

A

Allows economic activity to flourish
Allow cold environments to be exploited for whatever resources

57
Q

Describe sustainable management on the spectrum of management

A

Used resources to benefit the existing community
Conserve resources for future generations

58
Q

Describe comprehensive conservation on the spectrum of management

A

Aims to protect and conserve glacial and periglacial environments as wilderness
Organised eco-tourism and eco-farming
Exploitative activities not permitted

59
Q

Factors that influence management strategy

A

Population densities
Stakeholders(players)
Legislative frameworks
Mandatory legislation is most effective

60
Q

What is the alpine convention

A

An international treaty between alpine countries for the sustainable development and protection of the Alps

61
Q

How do crevasses form

A

Tension cracks caused by the bucking of the glacier as it flows over a rock step

62
Q

what are lateral moraines

A

Lateral moraine forms at the edge of the glacier and consists of rock fragments from the side of the valley

63
Q

what are medial moraines

A

Medial moraine is found in the middle of a glaciated valley and is formed by the merging of two sets of lateral moraine

64
Q

where do terminal moraines form

A

forms at the furthest end of the glacier and marks its maximum advance

65
Q

what are recessional moraines

A

Recessional moraine is similar to terminal moraine, but these mark locations where the glacier may have paused in its retreat, allowing deposition to occur.

66
Q

what are drumlins

A

oval-shaped small hills and form in previously glaciated lowland area. From their distribution, it is possible to work out the direction of glacier movement.

67
Q

what is an interglacial

A

a relatively warm period of several thousands of years in which glaciers predominately retreat

68
Q

what is calving

A

the breaking up of glacial ice, that extends over oceans, creating ice bergs

69
Q

what is glacier mass balance

A

the net difference between accumulation and ablation over the course of one year

70
Q

what does proglacial mean

A

the environment directly in advance of a glacier

71
Q

how many were killed at south base camp Everest by a 7.8 magnitude earthquake

A

22

72
Q

how much have glaciers shrunk in the last 50 years

A

13%

73
Q

how can you reduce tourism in Sagarmatha national park

A

limit the number of permits given to climbers
reduce group sizes

74
Q

what are ice contact landforms

A

kame
kame terrace
esker

75
Q

what are proglacial landforms

A

outwash plain
kettle hole
proglacial lake
varves

76
Q

what is the difference between ice contact landforms and proglacial landforms

A

ice contact result from the deposition of material carried by the ice
proglacial result from deposition by meltwater beyond the glaciers snout

77
Q

what is an esker

A

a long, narrow ridge of deposits. sub-glacial streams carry large amounts of rock debris due to their high hydrostatic pressure, as glacier melts deposited at a consistent rate

78
Q

what is an outwash plain

A

a flat expanse of debris in front of glacier snout. as meltwater streams emerge from the glacier they gradually lose their energy and deposit their debris load. coarse sands first then clay later

79
Q

what is a kettle hole

A

a circular depression. as the glacier retreats, detached blocks of ice remain, meltwater streams cover them in deposits, so when the ice melts a depression is left

80
Q

what is a proglacial lake

A

a lake formed at the snout of the glacier. formed by the damming action of a terminal or recessional moraine

81
Q

in the little ice age where did glaciers advance and why did it not become an interstadial

A

advanced in the north and south hemisphere
and was stopped by the industrial revolution

82
Q

what factors affect glacier movement

A

size (greater thickness=greater pressure)
altitude (snowfall increases)
variations in mass balance
slope
lithology

83
Q

how many people will be affected if meltwater regimes change in Asia

A

the UN estimates that 40% of the global population could be affected by the changes to meltwater regimes in Asia

84
Q

how many of the Himalayan glaciers are retreating

A

70%

85
Q

how are landscapes vulnerable from uncertain futures of climate change

A

forest dieback: rainforests could change into less productive farmland

86
Q

how will the water cycle be impacted from the uncertain futures of climate change

A

if the thermohaline circulation changes the this could change how oceans and atmosphere transfer heat energy, causing greater warming and more ice melt

87
Q

what human action leads to uncertain futures of climate change

A

governance- decisions
conflict
population growth
technology

88
Q

what physical systems lead to uncertain futures of climate change

A

residency times
feedback mechanisms
tipping points
thermohaline circulation

89
Q

What are varves and how are they formed

A

Found in the deposits of glacial lakes
Consist of two distinct layers of sediment, one being lighter coloured sand material and the other dark clay material

Geography (9 decks)

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