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AS Geography > Glacial Systems and Landscapes Definitions > Flashcards

Glacial Systems and Landscapes Definitions Flashcards

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1
Q

What is ablation?

A

The loss of mass from a glacier (e.g. iceberg calving, meltwater, sublimation).

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2
Q

What is abrasion?

A

Small rocks within the base of the glacier rub against and erode the bedrock, leaving behind striations.

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3
Q

What is accumulation?

A

The addition of mass to a glacier (e.g. direct snowfall, blown snow, avalanches).

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4
Q

What is the active layer?

A

The top layer of soil in periglacial environments above the permafrost, which thaws annually in summer.

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5
Q

What is an alpine region?

A

An area of low temperature in high altitude, mountainous areas (3000m+).

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6
Q

What is an arête?

A

A knife-shaped ridge formed between two corries.

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7
Q

What is basal ice melting?

A

The high pressure of a glacier causes meltwater, which will then erode the bedrock through fluvial erosion.

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8
Q

What is basal sliding?

A

The movement of a glacier due to lubrication from subglacial meltwater.

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9
Q

What is a blockfield?

A

A rock-strewn landscape caused by extensive freeze-thaw weathering.

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10
Q

What is a cold-based glacier?

A

Polar glaciers where the temperature remains below freezing and there is little ice movement as the glacier is frozen to the bedrock.

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11
Q

What is compressional flow?

A

Ice builds up and thickens as a glacier travels over a shallow gradient.

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12
Q

What is a corrie?

A

An armchair-shaped rock basin on the sides of mountains, formed through nivation and rotational slip in a hollow.

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13
Q

What is crushing?

A

The weight of a glacier causes the bedrock to fracture.

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14
Q

What is a drumlin?

A

A small dome-shaped hill formed due to deposition behind a resistant obstacle.

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15
Q

What is environmental fragility?

A

When an environment is vulnerable or at risk, with a low resilience and ability to adapt or recover from disruptions.

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16
Q

What is an erratic?

A

A large boulder deposited by a glacier in an area of completely different geology.

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17
Q

What is an esker?

A

A long, sinuous ridge of deposited glacial material which follows the path of a previous subglacial meltwater stream.

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18
Q

What is extensional flow?

A

Ice thins out and creates crevasses as a glacier travels over a steep gradient.

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19
Q

What is fluvial erosion?

A

Water within a glacier erodes the bedrock over time (e.g. hydraulic action, attrition).

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20
Q

What is frost heave?

A

The freezing and expansion of water in the soil, resulting in uplift and patterned ground.

21
Q

What is the glacial budget?

A

The difference between annual accumulation and ablation (mass balance).

22
Q

What is a glacial period?

A

A period of time with colder than average global temperatures, causing glacial advance and falling sea levels.

23
Q

What is a glacial trough?

A

A U-shaped valley formed due to glacial scouring of a pre-existing V-shaped river valley.

24
Q

What is a hanging valley?

A

A tributary valley from before glaciation is left hanging above a main valley due to the main valley glacier’s large erosive power.

25
Q

What is the Holocene epoch?

A

The period of geological history with limited ice cover from 11,700 years ago to the present day.

26
Q

What is an ice wedge?

A

Narrow cracks in the active layer formed through repeated infiltration and freezing of water.

27
Q

What is an interglacial period?

A

A period of time with warmer than average global temperatures, causing glacial retreat and rising sea levels.

28
Q

What is internal deformation?

A

Ice movement caused by ice crystals aligning under pressure and sliding over each other.

29
Q

What is a kame?

A

A small mound of partially sorted sand and gravel left on the valley floor as a glacier melts.

30
Q

What is a Milankovitch cycle?

A

Collective changes in Earth’s orbit, tilt and axis of rotation.

31
Q

What is a meltwater channel?

A

A stream of meltwater formed through higher temperatures and pressure.

32
Q

What is a moraine?

A

A ridge of deposited glacial material.

33
Q

What is nivation?

A

Erosion underneath a patch of snow caused by alternating freezing and thawing.

34
Q

What is orbital eccentricity?

A

How far a planet’s orbit is from being perfectly circular.

35
Q

What is an outwash plain?

A

Large area of stratified and deposited fluvioglacial sediment at the snout of a glacier.

36
Q

What is patterned ground?

A

Polygon-shaped cracks in the ground caused by frost heave of small stones within the active layer.

37
Q

What is a periglacial environment?

A

A cold environment found on the edges of polar or alpine regions which contains permafrost.

38
Q

What is permafrost?

A

Ground that remains below freezing for two continuous years in periglacial environments.

39
Q

What is a pingo?

A

A dome-shaped mound formed as ground is forced upward due to frost heave.

40
Q

What is plucking?

A

Rocks becoming dislodged as a glacier that was frozen onto the rock outcrop moves, causing erosion.

41
Q

What is a polar environment?

A

Cold environments that are located at high latitudes with extremely low temperatures.

42
Q

What is a roche moutonee?

A

A resistant rock which is eroded as a glacier moves over it.

43
Q

What is solifluction?

A

The slow, downslope movement of soil which has become waterlogged during the summer thaw.

44
Q

What is a solifluction lobe?

A

A tonge-shaped lobe in the soil formed due to solifluction and waterlogged soil.

45
Q

What is a terracette?

A

A ridge of narrow steps with small treads which run parallel across a hillslide, formed as vegetation traps sediment created through frost heave.

46
Q

What is a thermokarst?

A

A depression formed in the ground as permafrost melts and subsidence occurs.

47
Q

What is a till plain?

A

A large expanse of glacial till formed behind terminal moraines in areas of flat relief.

48
Q

What is a warm-based glacier?

A

Temperate glaciers where the higher temperatures create basal metlwater, allowing basal sliding to occur.

AS Geography (33 decks)

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