AQA Geography - Glacial Landforms

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name some Erosional landforms
Corries/Cirques/ Cwms Arêtes Pyramidal Peaks U shaped Valley/ Glacial Troughs Hanging Valley Roche Moutonee Truncated Spur
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Corries/Cirques/ Cwms
A Corrie is an armchair shaped depression with a steep back wall and a shallow rock lip
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how are corries formed?
formed when lying snow accumulates over a number of years and compresses lower layers into ice (firn) in a hollow. Once it has developed a sufficient volume, gravity causes it to move in a rotational manner out of the hollow and down the mountain sid
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Arêtes
Where two corries occur back to back and headward recession (cutting back) takes place over time forming a narrow, steep, rocky ridge between the two corries.
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Pyramidal Peak
If three or more corries erode back to back then the result is a ‘Pyramidal Peak’
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U shaped Valley
These are valleys formed by the glacial processes of weathering, erosion and transportation. They have steep sides and flat floors. Unlike V-shaped river valleys, glacial troughs are straight as they have truncated any interlocking spurs which existe
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Glacial Troughs
These are where interlocking spurs (the result of meandering river erosion) which predate the glacier are eroded and amputated by the straight-flowing glacier as it drives a path down a valley.
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Hanging valleys
These are formed by tributary glaciers which enter a glacial trough. Unlike in river landscapes they do not cut down to the level of the main valley as the glaciers they carried were considerably smaller, but instead lie suspended above in the valley
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Roches moutonnées
These are asymmetrical rocky outcrops in the trough floor. The up-valley side (stoss) gently slopes and is smoothed by abrasion of the glacier. The down-valley side (lee) is steep in gradient, and subject to plucking as ice accelerates past it.
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Drumlins
large hill-sized oval mounds caused by glaciers dropping their basal debris load as a result of friction.
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Erratics
these are rock fragments and boulders that differ from the local geology. They are transported within the glacier and deposited on top of different geology when the glacier melts and retreats.
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Till plains
when a large section of ice detaches from the main body of the glacier and melts, the suspended debris will be deposited and form a large plain of unsorted till.
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Moraines
these are composed of rocky debris that has been removed from the valley sides and floor by weathering and erosion and carried downhill by glaciers
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Fluvioglacial landforms
are those that are created by the work of meltwater streams in front of an often retreating glacier.
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what is the difference between fluvioglacial and meltwater channel?
tend to be unstratified (have no layers), unsorted and angular, whereas meltwater changes these glacial sediments or tills by sorting them by size, stratifying them into layers and rounding the sediments.
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How are Fluvioglacial landforms created?
Fluvioglacial landforms are created by the meltwater from glaciers, largely through deposition but also by erosion.
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Jokulhaups
Big glacial flood when meltwater build up can’t be contained
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Eskers
winding/sinuous ridges of often coarse sands and gravels that are deposited by melt water as it flowed in a channel beneath.
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How are eskers produced?
Produced by subglacial streams Deposited when melt water reduces in winter and exposed when the glacier melts.
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How are eskers found?
Material is rounded due to water erosion. Often stratified (layered) They vary in height – 5-20m for small eskers and length – from a km to 400km
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Kames
Rounded mounds/hills of fluvioglacial deposits (sorted, often stratified, coarse sands and gravel).
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where are kames found?
are found near the end of the former glacier as it began to retreat.
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where are kames terraces found?
Kame terraces are found where meltwater runs between the glacier and the sidewall and material is deposited (sorted) when flow is reduced.
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KAMES VS ESKERS
Kames – supraglacial material Eskers – subglacial material
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How are outwash plains created?
Outwash plains are created by both erosion and deposition. They are areas that may have been glaciated by ice sheets and then affected by melt water or they may be areas in front of the snout.
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Patterned ground
Patterned ground is a term given to the ground which has surface material distributed across it in a pattern. The examples of patterned ground include stripes, circles, polygons, ovals and garlands
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Ice wedges
Ice wedges are vertical masses of ice that penetrate down to 10 metres from the surface in some cases. They are formed as a result of the large amount of ground ice present and following significant temperature fluctuations.
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Pingos
Pingos are dome shaped hills that are commonly up to 500m in diameter and up to 50 meters in height. At the core of the pingo is an ice lens of varying size, and the surface layer is made of soil often topped with vegetation.
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open system pingos
occur in areas of discontinuous permafrost. where water that forms the ice lens comes from outside of the system
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closed system pingos
where the water required for ice lens formation is contained within the area where the pingo is formed.
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Other cards in this set

Card 2

Front

Corries/Cirques/ Cwms

Back

A Corrie is an armchair shaped depression with a steep back wall and a shallow rock lip

Card 3

Front

how are corries formed?

Back

Preview of the front of card 3

Card 4

Front

Arêtes

Back

Preview of the front of card 4

Card 5

Front

Pyramidal Peak

Back

Preview of the front of card 5
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