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Physical Geography > Glaciated Landscapes - Set 3 > Flashcards

Glaciated Landscapes - Set 3 Flashcards

1
Q

Till plains

A

Large, flat plains of till in lowland landscapes - when ice retreats large amounts of material are deposited over a sizeable area due to melting

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2
Q

Lodgement till

A

Often very well rounded but quite structureless

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3
Q

Ablation till

A

More angular clasts - may be sorted than lodgement till

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4
Q

Rose diagrams

A

used to plot the orientation of the clasts

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5
Q

What term did periglacial originally refer to

A

To refer to climate conditions and landscapes - characterised the areas near the margins of the glacier ice during the Pleistocene

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6
Q

What are periglacial landscapes like

A
  • Intense frosts during winter and on snow free ground during the summer
  • Average highest temp = 7 degrees
  • temp below 0 degrees for at least 9 months and -10 degrees for at least 6 months
  • precipitation low = less than 600mm annually
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7
Q

Permafrost

A

Permanently frozen ground

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8
Q

Continuous permafrost

A

Forms in the coldest areas of the world - can extend for 100s of metres down

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9
Q

Discontinuous permafrost

A

More fragmented and thinner than continuous permafrost

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10
Q

Sporadic permafrost

A

Occurs at margins of periglacial environment and is usually fragmented - only a few metres deep

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11
Q

Present day location of permafrost

A
  • Continuous permafrost is located in or just outside the arctic circle e.g. Greenland and Alaska - 20% of Earth experiences periglacial conditions - Had previously been 33%
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12
Q

Factors that effect the distribution of permafrost

A
  • Proximity of water bodies - water retains heat for longer
  • Slope angle - determines amount of solar radiation getting to the floor
  • Character of ground surface = Dark rocks absorb more solar radiation etc
  • Vegetation cover - Insulates ground
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13
Q

Moulins

A

Vertical well-like shaft within a glacier through which water enters from the surface and travels towards the base
-up to 10m wide

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14
Q

When are Fluvio-glacial streams at their most powerful

A

When deglaciation occurs, which leads to high discharge and thus more erosion

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15
Q

Fluvio-glacial landforms - Ice contact - Eskers

A

Material is deposited in subglacial tunnels as the supply of meltwater decreases - sediment slumps into a mound

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16
Q

Fluvio-glacial landforms - Ice contact - Kame-terraces

A
  • Sediment accumulates in ponds and lakes, trapped between lobes of glacier ice
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17
Q

Fluvio-glacial landforms - Ice contact - Delta Kames

A

Deposition of material in a hollow - as the ice melts, the kame emerges as a hump of sediment in a pyramid shape

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18
Q

Fluvio-glacial landforms - Proglacial - Kettle holes

A

Blocks of ice separated from glacier - buried by outwash material - melt and leave behind depressions which fill with water

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19
Q

Fluvio-glacial landforms - Proglacial - Sandur

A

Meltwater stream loses energy - material deposited with largest ear glacier snout and smallest sediment furthest away

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20
Q

Fluvio-glacial landforms - Proglacial - Proglacial lakes

A

Front of glacier where meltwater from glacier becomes impounded - bound by terminal moraines etc - also known as ice margin lake

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21
Q

Fluvio-glacial landforms - Proglacial - Varves

A
  • Stratified sediments found at the bottom of glacial lakes
  • Sediment carried by meltwater streams deposited - larger layers represent summer where lot’s of meltwater is available
22
Q

Ice-contact Fluvio-glacial deposits

A

Meltwater deposits

23
Q

Glacial till

A
  • Angular clasts
  • Unsorted
  • Diamiction = poorly sorted and non-stratified)
24
Q

Lodgement till

A
  • More well rounded than glacial till
  • Unsorted
  • Process occurs beneath the ice mass
25
Ablation till
- Slightly more angular than lodgement till - Often sorted by size - Refers to debris being dumped when glacier melts
26
Fluvio-glacial sediments
- Smaller - Smoothest clasts - Sorted horizontally
27
Frost heave
- Expansion of water as it freezes - pushes stones to surface - then become organised into stone circles etc
28
Solifluction
- Only happens on non-frozen ground - Caused by alternate freezing and thawing - water reduces friction between soil particles
29
Gelifluction
- Occurs on frozen ground - Soil particles breakdown during the winter months - summer temps than melt ice - slight gradient in permafrost causes dislodged material to slump
30
Nivation
- Combined action of freeze-thaw, Solifluction and gelifluction - Occurs under snow patch - causes underlying rocks to be eroded - hollow is left when snow melts
31
Aeolian processes
- Unobstructed winds blow across periglacial landscapes which cause erosion through wind abrasion - Dislodges fine material
32
Periglacial landforms - Ice wedges
- Formed by freeze thaw weathering - repeated until ice wedges grows up to 3 metres deep
33
Periglacial landforms - Patterned ground
- Features including sone circles, nets and polygons etc - Formed through frost heave - Polygon patterned ground found on gently sloping landscapes whereas stone stripes are found on steeper landscapes
34
Periglacial landforms - Nivation hollows
Underlying rocks eroded but snow patch remains. then melts in spring and eroded particles under snow move downslope leaving behind a hollow
35
Periglacial landforms - Pingo
- Dome shaped hills with ice lens in the centre - Ice lens = moisture accumulates in the soil and freezes - up to 70m high
36
Pingo - open system = discontinuous permafrost
- Ice core grows as it draws in ground water - Water gets there through capillary action and hydraulic pressure
37
Pingo - closed system = continuous permafrost
- Lake filled with sediment which traps water underneath - lake then shrinks and permafrost advances - water put under pressure and freezing forms on ice lens - expands pushing up earth above it
38
Rupture pingos
- rupture if become too large - Cracks expose ice lens to the atmosphere - ice then melts m
39
How much of Canada covered in permafrost
- 50% - Most continuous permafrost in north with thhe permafrost becoming more sporadic as it moves south
40
Examples of landforms in Canada
- Ice wedges = Dempster highway - Pingos = Doyle creek - Blockfields = Melville peninsula
41
Economic use of glacial environments - Farming
- Many in developing countries rely on subsidence farming e.g. Bolivia where 70% of pop lives in high Andes - Mobile phones = provide more opportunities for poor
42
Economic use of glacial environments - Forestry
- Carried out by forestry commission in UK - Main tree in UK = Conifers as they grow too quick
43
Economic use of glacial environments - Hydroelectricity
- Norway and New Zealand get over 90% of electricity from HEP - Switzerland has over 500 HEP stations
44
Economic use of glacial environments - Tourism
Examples: - Everest base camp - permitted numbers allowed to visit - South west Iceland - Ski and snowcat rides on glacier
45
Glaciers use for water
- 75% global freshwater locked up in ice - 2% of all water found in glaciers - Lake district contains ribbon lakes which have been dammed and used for water collection - Glaciers also important as they produce most water in late summer when other water sources dry up
46
Carbon sink
natural or artificial reservoir that absorbs more carbon than it releases
47
Tundra environments
- Tundra plants need to adapt to low temps, dry winds and snow blasts - system has low biodiversity and low nutrient content - Humans lead to removal of this vegetation to build infrastructure - Acid rain also damages these plants as it leads to thermokarst conditions = thawing of permafrost
48
Cultural value of glacial environment's - Climbing mount Kailash
- Sacred in 4 religions - never climbed due to this - It is banned to climb as it is a representation of the 'nine-story swastika'
49
Sacred landscape under threat - Nepal and Himalayas
- Home to communities such as the Jirel and Sharchops - Ways of life threatened with changes to environment - WWF committed to supporting them
50
The Arctic's Inuit culture
- Named Eskimos = eaters of raw flesh - First ate whale and walrus etc - left undisturbed until cold war - availability of western healthcare etc changed their way of life - by 1960s they became dependent on Western commodities - now suffer from high obesity rates and drug addiction

Physical Geography (15 decks)

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