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Geography > Glaciation - Unit 5 > Flashcards

Glaciation - Unit 5 Flashcards

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1
Q

How does a flowing ice body move?

A

Through glacial transportation

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2
Q

How does flowing meltwater move?

A

Through fluvial transportation

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3
Q

Where can rock debris be located and transported?

A

1- Transported on surface (supraglacial debris)
Glacial and fluvioglacial
2- Transported within (englacial debris)
Glacial and fluvioglacial
3- Transported at the base (subglacial debris)
Glacial and fluvioglacial
4- Transported away from the front (proglacial debris)
Fluvioglacial only

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4
Q

What is lateral moraine?

A

When supraglacial debris is concentrated in bands at the sides of the glacier

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5
Q

What is medial moraine?

A

When supraglacial debris is concentrated in the middle of the glacier

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6
Q

Give 2 ways that englacial debris is formed

A

1- Supraglacial debris that becomes buried by snowfall

2- When 2 separate valley glaciers converge

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7
Q

What 2 processes mainly form subglacial debris?

A

Abrasion and plucking

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8
Q

Give 4 differences between glacial and fluviglacial debris

A
  • Glacial till is angular
  • Fluvioglacial deposits are rounded
  • Glacier till is unstratified
  • Fluvioglacial deposits are stratified
  • Glacial till is unsorted
  • Fluvioglacial deposits are sorted
  • Glacial till is different sizes
  • Fluvioglacial deposits are similar sizes
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9
Q

Why are glacial and fluvioglacial sediment so different?

A

Glacial - rock debris entrained within glacial ice generally experiences few changes as it’s transported as it is fixed within the ice, with the exception of subglacial debris, which is eroded away due to abrasion as it is dragged over bedrock = produces ‘rock flour’
Fluvioglacial - water has limited ability to transport rock debris. The size of clasts it can transport is a function of the velocity of the flowing water (shown on Hjulstom curve)

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10
Q

Give 6 examples of landforms formed by glacial ice

A 
1- Drumlins
2- Terminal moraine
3- Recessional moraine
4- Lateral moraine
5- Medial moraine
6- Push moraine
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11
Q

Name the landscape where glacial ice landforms are found

A

Till plain

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12
Q

Give 6 examples of landforms formed by meltwater

A 
1- Eskers
2- Kames
3- Kame terraces
4- Kettle holes
5- Kettle lakes
6- Varves
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13
Q

Name the landscape where meltwater landforms are found

A

Sandur

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14
Q

What 3 categories can glacial till be subdivided into?

A

1- Lodgement till
2- Ablation till
3- Deformation till

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15
Q

How is lodgement till formed?

A
  • Forms subglacially
  • Plastered onto underlying surface by glacier due to friction
  • It is compacted, sorted and stratified
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16
Q

How is ablation till formed?

A
  • Deposited from sub, en and supra glacial debris due to ablation
  • It is poorly compacted, unsorted and unstratified
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17
Q

How is deformation till formed?

A
  • If a glacier re-advances over an area of till previously deposited, underlying till sediment can be folded
  • It is compacted, contain many rock types and the patterns reflect the stresses involved in its formation
18
Q

What is a moraine?

A

An accumulation of glacial debris

19
Q

What is a drumlin?

A

An elongated hill, streamlined in the direction of ice flow and composed largely of glacial deposits

20
Q

What is the deformational theory of drumlin formation?

A
  • Glacier moves over obstacle and till is plastered around it
  • Happens when there is a large amount of subglacial debris
21
Q

How does a terminal moraine form?

A
  • When ice melts and deposits all the moraine it was transporting at the front of glacier
22
Q

How do recessional moraines form?

A
  • Same manner as terminal moraines but they represent a location where the glacier paused for a considerable time during its retreat
23
Q

How do push moraines form?

A
  • When a glacier advances over existing moraine, pushing the moraine into a new ridge
24
Q

How can ice-contact fluvioglacial deposits be deposited?

A

Subglacially (eskers)

Supraglacially (kames)

25
Q

What are eskers?

A

Long, sinuous ridges of sands, gravels and pebbles deposited by meltwater streams/rivers flowing through subglacial, and sometimes englacial, tunnels. They can be up to 20m high and 3km wide

26
Q

How are eskers formed?

A
  • Subglacial stream forms due to increased pressure
  • When glacier retreats, the stream stops flowing as hydrostatic pressure from glacier is lost
  • Deposits all its material as it doesn’t have the energy to carry it
27
Q

Describe the clasts in an eskers sediment

A
  • Rounded
  • Sorted
  • Stratified layers
28
Q

Give an example of an esker

A

Munro Esker

29
Q

What are kames?

A

A deposited mound of sediment left in the path of a retreating glacier

30
Q

How are kames formed?

A
  • Formed supraglacially
  • Rock fall from valley enters crevasses in glacier
  • Crevasses move closer to the base as glacier melts
  • Dumped as a mound of sediment when reached valley bed
31
Q

What are kame terraces?

A

A deposited mound of sediment at the sides of the valley

32
Q

How are kame terraces formed?

A
  • Pressure between valley sides and glacier forms an ice-marginal channel
  • As water, carrying sediment, travels into valley, it collects in channel
  • Channel is not flowing so it deposits material
  • When glacier retreats, it leaves sediment at the valley sides
33
Q

Describe the clasts in a kame/kame terrace sediment

A
  • Angular
  • Sorted
  • Stratified
34
Q

What are kettle holes and kettle hole lakes?

A

A small lake formed from melted dead ice in the valley

35
Q

Give an example of where kames/kame terraces are found?

A

East Lothian, Scotland

36
Q

How do kettle holes form?

A
  • Glacier retreats, leaving behind dead ice
  • Meltwater from glacier deposits sediment around dead ice
  • Over time, sediment builds up
  • As temp increases, dead ice melts and a small lake is created
37
Q

Give an example of where kettle holes can be found

A

North Shropshire

38
Q

What are varves?

A

The varying layers of sediment that gets deposited due to seasonal rates of deposition

39
Q

How do varves form?

A
  • Winter = less deposition as there is less meltwater produced
  • Smaller particles are deposited in winter
  • Summer = more deposition as there is more meltwater produced
  • Larger particles are deposited in summer
  • Happens each year, building up varying layers of sediment
40
Q

What is a sandur/outwash plain?

A

The flat landscape formed by fluvioglacial deposition in front of a retreating icesheet

Geography (15 decks)

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