Unit 4 Notes Flashcards

1
Q

What is glacial transportation?

A

Sediment, transported by a flowing ice body.

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2
Q

What is fluvial transportation?

A

Sediment transported by flowing meltwater.

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3
Q

Which processes affect supraglacial debris?

A

Glacial and Fluvio glacial.

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4
Q

Which processes affect englacial debris?

A

Glacial and fluvioglacial.

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5
Q

Which processes affect subglacial debris?

A

Glacial and fluvioglacial.

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6
Q

Which processes affect proglacial debris?

A

Fluvioglacial.

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7
Q

What is erratic?

A

Different rock types to the bedrock they sit on.

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8
Q

What will extensional flow result in?

A

Supraglacial debris falling down crevasses becoming englacial debris.

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9
Q

What will compressional flow lead to?

A

Sub or englacial material being moved towards the surface, and becomes supraglacial debris.

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10
Q

Which landforms are glacial?

A

Drumlins, Recessional moraine, terminal moraine, lateral moraine, medial moraine, push moraine.

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11
Q

Which landforms are fluvioglacial?

A

Eskers, Kames, Kame terraces, Kettle holes, Kettle lakes, varves.

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12
Q

Where are glacial landforms found?

A

A till plain.

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13
Q

Where are fluvioglacial deposits found?

A

Outwash Plain.

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14
Q

What is lodgement till?

A

Till formed subglacially being plastered onto underlying surface. Friction between debris and bed - greater than drag produced by ice moving over it.

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15
Q

What is ablation till?

A

Till deposited from sub, en, and supraglacial debris, due to ablation poorly sorted, unstratified.

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16
Q

What is deformation till?

A

Underlying till being folded or faulted when a glacier re-advances.

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17
Q

What is a moraine?

A

An accumulation of glacial debris deposited by a glacier.

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18
Q

What is a till plain?

A

Glacial moraines covering large areas of land, producing a flat area.

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19
Q

What is the fluvial theory of drumlin formation?

A

Drumlin formation is due to sub-glacial meltwater flooding, depositing fluvioglacial material.

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20
Q

What is the deformational theory?

A

When a glacier moves over an obstacle at the base of the glacier, till is plastered around it. Lodgement till becomes streamlined as the glacier flows over it.

21
Q

When do medial moraines form?

A

When two glaciers converge, becoming a lateral moraine.

22
Q

What are lateral moraines formed from?

A

Piles of glacially-transported rocks, debris dropped by ice.

23
Q

What do terminal moraines mark?

A

The furthest advance of a glacier.

24
Q

Where is debris deposited?

A

The furthest point which the glacier reaches.

25
Q

What is the difference between recessional and terminal moraines?

A

Recessional moraines are formed where the glacier pauses for a considerable time during its retreat.

26
Q

When do push moraines form?

A

When a glacier advances over existing moraine.

27
Q

What are the characteristics of glacial till?

A

Poorly sorted, different shapes and sizes, no stratification, angular and sub-angular.

28
Q

What are the characteristics of fluvioglacial till?

A

Well sorted, clear stratification, rounded/sub-rounded debris.

29
Q

What does sorting refer to?

A

The arrangement of rock fragments into similar sizes.

30
Q

What does stratification refer to?

A

The layering of similar sized clasts.

31
Q

Are eskers subglacial or supraglacial?

A

Subglacial.

32
Q

What is the first step in the formation of an esker?

A

Running water at a high velocity due to hydrostatic pressure transports a large quantity of sediment which become rounded due to extensive attrition.

33
Q

What is the second step in esker formation?

A

Fluctuating velocities due to seasonal variations in meltwater enable deposition to occur.

34
Q

What is the third step in esker formation?

A

The tunnel may become blocked, stopping the flow of water.

35
Q

What is imbrication?

A

Clasts aligning themselves in the direction of the flowing water.

36
Q

Do kames form supra or subglacially?

A

Supraglacially.

37
Q

What happens in the zone of ablation?

A

Surface meltwater streams pick up and transport supraglacial debris.

38
Q

What happens to meltwater streams in the zone of ablation?

A

They flow into lake depressions, on the ice surface. If the lake is at the glacier edge, a kame terrace forms. Away from the edge, a kame forms.

39
Q

What are the steps in formation of a kame?

A

Initial ice surface, ice surface melts and is lowered, continued ablation lowers ice surface, ice disappears, kames have been deposited on valley floor.

40
Q

Why are kame clasts angular?

A

Debris is only being moved a short distance, so there isn’t room for attrition.

41
Q

Why are kames sorted and unstratified?

A

Seasonal variation means there will be bands of rock which are similar in size.

42
Q

Why are kame terraces larger?

A

Freeze thaw weathering on the valley side.

43
Q

What are kettle holes?

A

Depressions found within the outwash plain located in front of a retreating glacier.

44
Q

What are the first two steps of kettle holes formation?

A

Blocks of ice are left behind by retreating glacier. Sediment shed from retreating glacier buries ice blocks.

45
Q

What are the last two steps of kettle hole formation?

A

Ice blocks melt away, and sediment collapses, groundwater falls in kettles.

46
Q

What are the characteristics of varves?

A

Stratified, made up of fine material.

47
Q

Why does a varve have coarse and fine layers?

A

Warmer summer months mean more ablation, faster streams, and transport of coarse materials. Colder winter months mean lower temperatures, less ablation, slower flowing streams, transport of fine materials.

48
Q

What is an outwash plain?

A

A flat landscape formed by fluvioglacial deposition in front of a retreating ice sheet.