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Geography > Glaciation part 3 > Flashcards

Glaciation part 3 Flashcards

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1
Q

What are Glacio-fluvial landforms?

A

Landforms that are created by meltwater.

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2
Q

What are glacio-fluvial deposits?

A

The result of deposition by glacial meltwater during a period of retreat or stagnation.

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3
Q

What are the characteristics of the glaciofluvial material?

A

Generally smaller than glacial till deposits.
rounded and smooth due to contact with water.
In layers.

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4
Q

What are the landforms created by glaciofluvial deposits?

A

Kames: Kame terraces and kame deltas.
Eskers
Outwash plains

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5
Q

What are Kames?

A

Mound like hills that are composed of sands and gravels.

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6
Q

How are Kames formed?

A

Formed as meltwater streams on the surface of the ice plunge down crevasses taking sediment with it.
This forms accumulation of material in the crevasses which are then left as ice melts.

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7
Q

What’s our example of Kames?

A

East Lothian, Scotland

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8
Q

What is the average size of Kames?

A

A few hundred metres long and tens of metres high.

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9
Q

What is a Kame terrace?

A

A flat top ridge that is formed from sorted material running along the edge of a valley glacier. Small troughs form.

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10
Q

How are Kame deltas formed?

A

Formed as en-glacial streams emerge at the snout of the glacier loosing energy and deposits their load on lakes. These could be pro-glacial lakes.

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11
Q

How are Eskers formed?

A

Mostly formed at margin of warm based glaciers due to the retreat/stagnation of ice. Meltwater streams follow tunnels beneath melting glacier and carry huge volumes of debris under pressure.
Deposition occurs in the tunnels when streams loose energy so blocks them, so water and deposits build up.

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12
Q

What is an outwash plain?

A

A flat expanse of sediment in the pro-glacial area. They lie beyond the snout of a glacier.

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13
Q

How are outwash plains formed?

A

Meltwater streams gradually loose energy as they enter lowland areas beyond the ice.
The largest and coarsest pieces drop first, followed by smaller.
Deposits are layered.

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14
Q

What are the typical characteristics of an outwash plain?

A

Often have braided streams.
Consists of stratified, graded and rounded deposits.
Kettle lakes can be found.

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15
Q

What are braided streams?

A

Form on an outwash plain where channels of meltwater become clogged, so encourages the stream to divide into smaller streams.

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16
Q

How is a kettle hole formed?

A

Formed as glacier retreat and large blocks of ice are calved from the main glacier and left on the outwash plain.
The stranded block of ice gradually gets surrounded and blocked by meltwater deposits/outwash.
The ice eventually melts away and leaves a depression. Rainfall will then fill the whole.

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17
Q

Why are glacio-fluvial deposits difficult to identify?

A

The repeated advancing and retreating of a glacier modifies the appearance of the landform.
Subjected to weathering, erosion and colonisation of vegetation.
Excess retreat in glacier so more outwash plain is exposed.

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18
Q

What are peri-glacial environments?

A

These are areas that have permafrost, Seasonal temperature variations above 0 degrees in summer.
Geomorphic processes are dominated by cycles of freeze thaw.

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19
Q

What percentage of the Earth’s surface is described as peri-glacial?

A

25%

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20
Q

What is permafrost?

A

Permanent frozen ground. The subsoil temp must be below 0 degrees for at least 2 consecutive years for it to develop.

21
Q

What are the types of permafrost?

A

Continuous
Discontinuous
Sporadic

22
Q

What is continuous permafrost?

A

Permanent permafrost.
A winter temperature of -50 degrees.

23
Q

What is discontinuous permafrost?

A

Breaks up rivers lakes and costal areas.
Temperature varies from -5 to -1.5 degrees.

24
Q

What is sporadic permafrost?

A

Isolated spots of permafrost.
1.5 to 0 degrees.

25
Q

What is the active layer?

A

The surface layer that occurs of the permafrosts meltwater.
The water is unable to drain away through the impermeable layer of frozen ground beneath so the soil becomes saturated creating boggy land.

26
Q

What is the talik?

A

Unfrozen ground that’s surrounded by permafrost.

27
Q

What is the tundra?

A

An area of open, treeless vegetation.

28
Q

What is frost action?

A

Freeze-thaw but in a periglacial environment.

29
Q

What is frost heave?

A

The process occurs under the surface and results in the upward movement of material through the active layer.

30
Q

How does frost heave occur?

A

As temperatures fall, water beneath the stones freezes, so expands by 9% and pushes the stone above going upwards.
Ground ice also pushes up fine material, producing a domed surface.

31
Q

What is ground ice development?

A

When water melts it soaks into the sub-surface of the rock, accumulating beneath the water table. Then freezes creating ground ice to expand which results to the surface to be pushed upwards.

32
Q

What is ground contraction?

A

Cold temperatures can cause soil contraction which creates cracks in the active layer and permafrost. Liquid can fill these cracks and freezes causing these cracks to expand over time.

33
Q

What is solifluction?

A

When the active layer melts, water cannot submerge down as ground is impermeable by the permafrost below so active layer becomes saturated and will move downslope.

34
Q

What are the peri-glacial landforms?

A

Patterned ground
Pingos

35
Q

How is patterned ground formed?

A

Frost heave pushes material and stones up towards and through the active layer to create a dome. This material then roles down the hills of the dome due to gravitational energy and creates polygons around the dome itself. The ground itself will relax as less till is pushed upwards.

36
Q

What is the typical size of a polygon in patterned ground?

A

1-2m in diameter.

37
Q

What is our example of patterned ground?

A

Leedon Tor, Dartmoor

38
Q

What are pingos?

A

Isolated hills containing a core of ice and are roughly circular when viewed from above. The summit of these features often has dilation cracks due to growth of ice core.

39
Q

What are ognips?

A

A collapsed pingo that may resemble a crater and contain a pond.

40
Q

How does a pingo grow?

A

As water is drawn in from the surrounding sediments towards the ice and so freezes in contact with it.

41
Q

What is our average size of a pingo?

A

50-500m diameter and 10-70 height

42
Q

What is our example of a pingo?

A

White swan, Connington

43
Q

What type of permafrost does an open system pingo have?

A

Discontinuous

44
Q

What type of permafrost does a closed system pingo have?

A

Continuous

45
Q

Where does the water source come from in an open system pingo?

A

Outside of the system

46
Q

Where does the water source come from in a closed system pingo?

A

Inside the system, trapped between the ice layers.

47
Q

Where would we typically find an open system pingo?

A

Valley bottoms

48
Q

Where would we typically find closed system pingos?

A

Low lying areas, small lakes

Geography (6 decks)

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