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Glaciation Flashcards

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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
associated glacial erosion processes
freeze-thaw and meltwater
26
four different glacial landform environments
periglacial, glacial, marginal and proglacial
27
what is a rouche moutonnees
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).
28
landforms of cirque glacier
cirques, aretes, pyramidal peak
29
landforms of valley glaciers
u-shaped valleys, truncated spurs, hanging valleys, ribbon lakes
30
landforms of ice sheet scouring
basins, knock & lochans, roche moutonnees
31
how does a cirque form
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
32
what happens during a cirque
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
33
how are basins created
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
34
how is knock and lochan created
topology occurs as the ice sheet advances it preferentially erodes through the ice sheet, scouring areas of dense jointing more than areas without joining
35
The 2 glacial deposition processes
Lodgement and ablation
36
Define lodgement
Beneath the ice mass, subglacial debris being carried,become lodged, occurs when friction is greater than drag force
37
Define ablation
Material is deposited as the glacier melts
38
Upland landforms and characteristics
Moraines- large glacial deposits. Drumlin-oval or egg shaped hill
39
Low land landforms and characteristics
Erratics - boulders picked up by ice and deposited Till plains- an extensive plain
40
What is supragcacial hydrology
Water on glacier formed by ice melting in summer Flows off, into a number of cracks similar to ordinary river system.
41
What is englacial hydrology
Structures in the ice (crevasses), allow water to penetrate in ice
42
Characteristics of fluvioglacial deposits
Smaller, more rounded, sorted horizontally, stratified vertically
43
What are kames and kames terraces and how are they formed
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
Values of glaciated landscapes
Cultural, economic, environmental, biodiversity, natural systems
45
2 example environmental values
Maintain a gene pool of wild organisms to ensure genetic variety Arctic and Antarctic environments are living labs
46
2 example economic values
Farming, tourism
47
2 biodiversity values
Tundra covers 8 million km 2 Permafrost increases fragility
48
how do glaciated landscapes maintain natural systems
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
3 natural threats
Lahars, glacial outburst, avalanches
50
What is a glacial outburst
A powerful flood, resulting from a bursting subglacial lake
51
How does tourism affect active temperate environments
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
Human activity threats to upland active and relict landscapes
Resource exploitation- oil in Alaska Tourism- footpath erosion Climate Change
53
Environmental impacts of human activities
Soil erosion (r) Changes to hydrological cycle (a) Thawing permafrost (a) Invasion of species due to warming(a)
54
Economic impacts of the environmental consequences
Decline in agriculture productivity Decline in tourism as a result of environmental degradation Decline in tourism from warming Increased energy insecurity
55
Who are the players in management approaches
Local government National government Conservationists NGOs International organisations Local people
56
Describe do nothing on the spectrum of management
Allows economic activity to flourish Allow cold environments to be exploited for whatever resources
57
Describe sustainable management on the spectrum of management
Used resources to benefit the existing community Conserve resources for future generations
58
Describe comprehensive conservation on the spectrum of management
Aims to protect and conserve glacial and periglacial environments as wilderness Organised eco-tourism and eco-farming Exploitative activities not permitted
59
Factors that influence management strategy
Population densities Stakeholders(players) Legislative frameworks Mandatory legislation is most effective
60
What is the alpine convention
An international treaty between alpine countries for the sustainable development and protection of the Alps
61
How do crevasses form
Tension cracks caused by the bucking of the glacier as it flows over a rock step
62
what are lateral moraines
Lateral moraine forms at the edge of the glacier and consists of rock fragments from the side of the valley
63
what are medial moraines
Medial moraine is found in the middle of a glaciated valley and is formed by the merging of two sets of lateral moraine
64
where do terminal moraines form
forms at the furthest end of the glacier and marks its maximum advance
65
what are recessional moraines
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
what are drumlins
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
what is an interglacial
a relatively warm period of several thousands of years in which glaciers predominately retreat
68
what is calving
the breaking up of glacial ice, that extends over oceans, creating ice bergs
69
what is glacier mass balance
the net difference between accumulation and ablation over the course of one year
70
what does proglacial mean
the environment directly in advance of a glacier
71
how many were killed at south base camp Everest by a 7.8 magnitude earthquake
22
72
how much have glaciers shrunk in the last 50 years
13%
73
how can you reduce tourism in Sagarmatha national park
limit the number of permits given to climbers reduce group sizes
74
what are ice contact landforms
kame kame terrace esker
75
what are proglacial landforms
outwash plain kettle hole proglacial lake varves
76
what is the difference between ice contact landforms and proglacial landforms
ice contact result from the deposition of material carried by the ice proglacial result from deposition by meltwater beyond the glaciers snout
77
what is an esker
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
what is an outwash plain
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
what is a kettle hole
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
what is a proglacial lake
a lake formed at the snout of the glacier. formed by the damming action of a terminal or recessional moraine
81
in the little ice age where did glaciers advance and why did it not become an interstadial
advanced in the north and south hemisphere and was stopped by the industrial revolution
82
what factors affect glacier movement
size (greater thickness=greater pressure) altitude (snowfall increases) variations in mass balance slope lithology
83
how many people will be affected if meltwater regimes change in Asia
the UN estimates that 40% of the global population could be affected by the changes to meltwater regimes in Asia
84
how many of the Himalayan glaciers are retreating
70%
85
how are landscapes vulnerable from uncertain futures of climate change
forest dieback: rainforests could change into less productive farmland
86
how will the water cycle be impacted from the uncertain futures of climate change
if the thermohaline circulation changes the this could change how oceans and atmosphere transfer heat energy, causing greater warming and more ice melt
87
what human action leads to uncertain futures of climate change
governance- decisions conflict population growth technology
88
what physical systems lead to uncertain futures of climate change
residency times feedback mechanisms tipping points thermohaline circulation
89
What are varves and how are they formed
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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