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Geography > Cold Environments > Flashcards

Cold Environments Flashcards

0
Q

What is a cold environment?

A

An area of land that experiences temperatures close to or below 0•c for a significant period of time.

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1
Q

Where are cold environments found?

A

High latitudes, high altitudes, middle of continents and ice/snow areas with the albedo effect.

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2
Q

What is a polar environment?

A

The most extreme cold environment where temperatures can reach -50•c in winter. They are cold deserts and surrounded by sea ice. Eg. Antarctica.

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3
Q

What is a periglacial environment?

A

Found on the fringes of polar and glacial regions where temperatures are frequently below 0•c so permafrost results. Eg. Parts of Siberia and Canada.

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4
Q

What is an alpine environment?

A

Cold areas of land above the tree line (2000m) where temperatures can drop to -10•c in winter but exceed 20•cabin summer. Both glacial and periglacial areas can be found within alpine environments. Eg. The Alps and the Himalayas.

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5
Q

What are glacial environments?

A

Areas covered by glaciers or ice sheets. Cold-based glaciers can be found in polar environments eg. Antarctica whilst warm-based glaciers can be found in alpine areas eg. the Alps.

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6
Q

What can cause global climate change?

A

Milankovitch cycles, sunspots, volcanic activity and changes in ocean currents.

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7
Q

What are glaciers?

A

Masses of ice (and debris) which are continually dynamic. They are open systems with inputs and outputs.

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8
Q

What are the main inputs into a glacier?

A

Precipitation (snow), avalanches and condensation.

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9
Q

What are the main outputs from a glacier?

A

Evaporation, sublimation (solid to gas), meltwater and calving.

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10
Q

What is the zone of accumulation?

A

Found at the source of the glacier where inputs exceed outputs. Accumulation occurs mostly during winter months due to high snowfall, low temperatures and strong winds.

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11
Q

What is the zone of ablation?

A

Found at the snout of the glacier where outputs exceed inputs. Ablation occurs mostly in summer months due to reduced snowfall and higher temperatures which lead to melting.

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12
Q

What is the equilibrium/firn line?

A

The dividing line between the zone of accumulation and the zone of ablation where inputs equal outputs. Gravity continually moves ice down to this line replacing that lost through ablation at the snout of the glacier.

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13
Q

What are cold-based glaciers?

A

Occur in polar latitudes and the base remains below freezing point meaning ice remains frozen to the bedrock and there is therefore little movement or erosion.

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14
Q

How do cold-based glaciers move?

A

Internal deformation. Ice crystals orientate themselves in the direction of ice flow and slide past each other downhill in response to gravity. The dresses applied by the weight of the ice can cause the crystals to deform.

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15
Q

What are warm-based glaciers?

A

Found in alpine areas and are mostly valley glaciers. Water is present throughout the glacier, which acts as a lubricant for movement especially at the base and erodes the underlying bedrock.

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16
Q

How do warm-based glaciers move?

A

Basal sliding, regelation flow, creep, extensional flow and compressional flow.

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17
Q

What is basal sliding?

A

Meltwater at the base of the glacier acts as a lubricant and allows sliding over bedrock (warm-based glacier).

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18
Q

What is regelation flow?

A

When a warm- based glacier meets a small raised obstacle whilst travelling down valley, there is increased pressure which causes melting. This meltwater allows slippage over the obstacle. The meltwater then refreezes on the downside of the obstacle, due to low pressure, leaving a thin regelation layer which pulls rock off the obstacle by plucking as it moves off. Forms a Roche Moutonnee.

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19
Q

What is creep?

A

When a warm-based glacier meets a large obstacle whilst travelling down valley, there is a large increase in pressure which results in plastic deformation of the ice. As the glacier becomes more plastic in behaviour it can creep/flow over the obstacle.

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20
Q

What is extensional flow?

A

When a warm-based glacier travels down a steep slope velocity increases which makes the ice become thinner. This results in crevasses forming in the ice.

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21
Q

What is compressional flow?

A

When a warm-based glacier travels down a gentle slope velocity decreases which makes the ice become thicker. He weight of the ice results in rotational movement.

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22
Q

What is the mass balance of a glacier?

A

The difference between the amount of accumulation and the amount of ablation from a glacier. Gives either a positive or negative mass balance.

23
Q

What is cumulative mass balance?

A

The total loss or gain of glacial mass since the start of the study period.

24
Q

What is frost-shattering?

A

A process of glacial erosion. Water in the glacier repeatedly freezes and thaws putting pressure on rocks causing them to break down.

25
Q

What is abrasion?

A

A process of erosion. Angular moraine in the glacier rubs against the valley sides and floor wearing it away.

26
Q

What is plucking?

A

A process of erosion. Glacial ice freezes into bedrock and pulls large pieces of rock away with it as it moves away.

27
Q

What is an arête?

A

A feature of upland glaciation. A narrow, knife-edged ridge with steep sides formed when two cities erode back to back. Eg. Striding Edge, Lake District.

28
Q

What is a pyramidal peak?

A

A feature of upland glaciation. A three-sided peak formed when three cities erode back to back.

29
Q

What is a hanging valley?

A

A feature of upland glaciation. In glacial times, a tributary glacier met a main glacier and different erosion meant the floor of the main valley became lower than the tributary valley. The tributary valley was then left hanging post-glaciation. Eg. Red Dell, Lake District.

30
Q

What are truncated Spurs?

A

A feature of upland glaciation. Glacial erosion along the valley sides removed the tips of interlocking Spurs forming a u-shaped valley wih cliff-like truncated Spurs.

31
Q

What is a glacial trough?

A

A feature of upland glaciation. Large, valley glaciers move through the valley eroding it into a u-shaped, steep-sides, flat-floored glacial trough.

32
Q

What is a ribbon lake?

A

A feature of upland glaciation. A glacier erodes less resistant rock in the valley floor forming a. Small, over deepened hollow, which collects water after the glacier retreats. Eg. Coniston Water, Lake District.

33
Q

What is a corrie?

A

A feature of upland glaciation. An armchair shaper rock hollow with a steep back wall, as well as an over deepened with a rock lip which often contains a small tarn.

34
Q

How do corries form?

A

During glaciation, snow accumulates on N/NE facing slopes and nivation causes underlying to break up leaving a small hollow. Meltwater games the eroded material away, deepening be hollow further. As the ice thickens, the weight of the ice causes it to move downhill and results in rotational movement. This movement and abrasion from moraine that has dropped to the base of the ice through the bergshund crevasse causes lots of erosion in the hollow. Frost shattering and plucking as the ice moves downhill causes a steep back wall whilst a rock lip forms where the ice thins and there is less erosion.

35
Q

How is moraine transported by a glacier?

A

Supra glacially, englacially or sub glacially.

36
Q

What are the main types of moraine?

A

Lateral moraine (deposition of till along the sides of he glacier), medial moraine (deposition of till in the centre of the valley where two lateral moraines join together), terminal moraine (deposition of till at the end if a glacier) and push moraine (when a glacier re advances pushing forward earlier moraines).

37
Q

What is till?

A

Sediment dropped by glacial ice. It is I modified by water and therefore consists of all grain sizes and is unsorted and unstratified. Ablation till is dropped when the glacier melts and not orientated whilst lodgement till is dropped when the glacier moves away and is orientated.

38
Q

What are erratics?

A

Rocks transported by glacial ice and dropped ex situ in an area of different geology where they are said to be out of place.

39
Q

What are drumlins?

A

Asymmetrical, tear-drop shaped mounds of till which are twice as long as they are wide. They can be up to 1500m long and 100m wide. They are aligned parallel to ice flow and are often found in swarms in an egg-in-basket landscape.

40
Q

What are the theories for drumlins formation?

A
  1. An obstacle under the ice causes material to be deposited around it, which is later streamlined by ice advance. 2. As a glacier enters lower ground down valley the ice spreads and thins and deposits material which is later streamlined by ice advance. 3. Glacial re-advance down valley reshapes previously deposited material.
41
Q

What is an out wash plain?

A

A fluvio-glacial landform. Broad flat area of deposition in front of the glacier by meltwater streams largely during the summer months. Material is sorted due to the presence of water.

42
Q

What are braided streams?

A

A fluvio-glacial landform. Braiding occurs due to seasonal variation in the discharge of melt water streams. During winter, discharge decrease and excess sediment is deposited which obstructs flow. This leads to braiding as water seeks the most efficient way through.

43
Q

What is an esker?

A

A fluvio-glacial landform. A long, sinuous ridge of sorted material deposited by meltwater streams flowing underneath the glacier. Deposition occurs during periods of low flow and a bed of material builds up which remains as an esker after glacial retreat and the stream dries up.

44
Q

What are kame mounds?

A

A fluvio-glacial landform. Material deposited in surface crevasses of the glacier are deposited in the valley floors in mounds after the glacier melts.

45
Q

What are kame terraces?

A

A fluvio-glacial landform. Melt water that runs between the glacier and valley sides deposits sediment against the valley sides which is sorted due to the presence of water.

46
Q

What are kame deltas?

A

A fluvio-glacial landform. Sediment is deposited annually within pro glacial lakes by meltwater streams droning a delta with distinct layering due to deposition of different material in different seasons.

47
Q

What is permafrost?

A

Permanently frozen ground where sub-soil temperatures must remain below 0•c for 2 years in order for it to develop. Consists of an active layer (during thaw), continuous/discontinuous/sporadic permafrost and talik.

48
Q

What is continuous permafrost?

A

Found in be coldest regions where re ground is permanently frozen and there is little or no thawing.

49
Q

What is discontinuous permafrost?

A

Found in slightly warmer regions where freezing conditions don’t reach as deep and there are breaks in the permafrost around lakes, rivers and sea.

50
Q

What is sporadic permafrost?

A

In areas where temperatures fluctuate around 0•c and summers are often warmer so permafrost only occurs in isolated areas.

51
Q

What is nivation?

A

A periglacial process. Frost shattering and solifluction occur in hollows beneath patches of snow on N/NE facing slopes leaving deep nivation hollows.

52
Q

What is solifluction?

A

A periglacial process. Melt water is released from the active layer of permafrost and can’t percolate downwards so he soil remains saturated and moves downslope. The rapid movement of soil downslope forms rounded, tongue like features called solifluction lobes.

53
Q

What is ground contraction?

A

A periglacial process. The active layer of permafrost refreezes during winter causing the soil to contract causing cracks on the surface. Repeated freezing and thawing widens and deepens the cracks forming ice wedges. The near polygonal patterns produced on the surface due to the ice wedges are called ice-wedge polygons.

54
Q

What is frost heave?

A

A periglacial process. Stones int he soil become colder quicker and moisture beneath gem freezes and expands. Repeated freezing and thawing results in the ice crystals heaving the stones upwards in the soil profile. Frost heaving and thawing can result in patterned ground. In gentle slopes, stone polygons are created but on steep slopes over 6•, stones are dragged downhill by gravity into stone stripes.

55
Q

How do open-system (East-Greenland type) pingos form?

A

A periglacial feature from groundwater freezing in discontinuous permafrost. Water infiltrates into the talik through breaks in the permafrost. It then freezes and expands to form a large ice cone which heaves overlying sediment upwards into a done-shaped pingo.

56
Q

How do closed-system (Mackenzie type) pingos form?

A

A periglacial feature from groundwater freezing in continuous permafrost. Small lakes insulate the ground so the area below remains unfrozen. During winter the unfrozen ground water freezes and expands forming a large ice core that is forced upwards as the permafrost advances to form a conical shaped pingo/ ruptured pingo.

Geography (2 decks)

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