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Geography > Glaciation > Flashcards

Glaciation Flashcards

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1
Q

What is a glacier?

A

A mass of ice moving down a valley.

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2
Q

How does a glacier form?

A

1) Snow falls and begins to accumulate into a mass.

2) As more snow forms, the mass begins to compress down and makes a compact structure (called an firn)

3) After more time, the air is fully pressed out and a solid block of ice forms

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3
Q

What are the two types of glaciers?

A

Temperate and Polar

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4
Q

What is a temperate glacier?

A

Glaciers which melt in the summer slightly when temperatures rise.

The meltwater makes the glacier melt due to basal flow. So is more likely to erode at a greater rate.

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5
Q

What is a polar glacier?

A

Glaciers which do not melt at all because the temperature is too low.

They do not have meltwater so move by internal deformation. Therefore less likely to erode and move slower.

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6
Q

What are the two zones of a glacier?

A

Upper and Lower

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7
Q

Describe the Upper Zone of a glacier

A

It has less pressure on it so has no meltwater.

Moves by internal flow.

Moves faster as there is no friction.

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8
Q

Describe the Lower Zone of a glacier

A

It has more pressure on it, so meltwater is present.

It moves via basal flow.

It moves slower when there is no meltwater due to increased friction with the bedrock.

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9
Q

What are the inputs of a glacier?

A

Precipitation and Avalanches

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10
Q

What are the transfers in a glacier?

A

The flow of ice

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11
Q

What are the outputs of a glacier?

A

Ablation, Evaporation and Sublimation

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12
Q

What is ablation?

A

The melting of ice

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13
Q

What is an Esker?

A

A sinuous trail of deposited material from a subglacial channel

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14
Q

How is an Esker formed?

A

1) A subglacial stream forms due to increased pressure

2) The channel carries the sediment

3) When the glacier retreats, the stream stops as the pressure is lost so the material is deposited as there is no energy to carry it.

4) It is left in a long line

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15
Q

What is a Kame?

A

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

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16
Q

How is a Kame formed?

A

1) Rock fall from the valley falls ontop of the glacier and into crevasses in the glacier

2) As deglaciation occurs, the crevasses move closer to the base as the glacier melts

3) When they reach the valley bed, the material is dumped onto the bed as a mount of sediment

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17
Q

What is a Kame Terrace?

A

A deposited mound of sediment at the sides of a valley

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18
Q

How is a Kame Terrace formed?

A

1) Pressure between the valley sides and glacier forms a ice-marginal lake

2) As water (carrying sediment) travels into the valley, it collects here

3) As the ice-marginal lake doesn’t flow, it deposits the material which when the glacier retreats, is left at the valley sides

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19
Q

What is a Delta Kame?

A

A Kame that forms in a proglacial lake

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20
Q

How are Delta Kames formed?

A

1) A subglacial channel is formed due to pressure

2) It entrains the material and transports it downstream

3) As the subglacial channel meets the proglacial lake, it loses energy so deposits the sediment

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21
Q

What is a drumlin?

A

A landform of shaped moraine

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22
Q

How is a drumlin formed?

A

1) When a glacier moves over moraine in the valley and it does not have the energy to erode the resistance rock inside the moraine.

2) As the glacier moves over the moraine, it begins to smooth the material as it moves back down the slope.

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23
Q

What are the characteristics of a drumlin?

A

1) ‘The Stoss’ - The short, steep side of the morraine

2) ‘The Lee’ - The long, sloping side of the morrain

3) Possible resistance rock in the middle

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24
Q

What is Till?

A

Till is unsorted sediment in the glacier valley

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25
Q

What are the two types of Till?

A

1) Lodgement - Till deposited from a moving glacier

2) Ablation - Till deposited from a melting glacier

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26
Q

What is morraine?

A

Glacial Till which had been sorted

27
Q

What is lateral moraine?

A

Moraine located on the sides of a glacier.

When the glacier moves down the valley, it erodes the sides, plucking them and removing sediment.

28
Q

What is ground moraine?

A

Moraine located at the base of the glacier.

It happens when material is picked up by the moving glacier

29
Q

What is medial moraine?

A

A line of moraine located in the middle of the glacier.

It happens when two glaciers merge and become a larger glacier. The lateral moraine sides join to meet in the middle

30
Q

What is terminal moraine?

A

It is the deposited moraine when the glacier has reached its furthest point and stopped.

31
Q

What is recessional moraine?

A

Lines of moraine deposited and sorted as the glacier retreats

32
Q

Define erosion.

A

The process by which parts of the valley are broken down due to movement of the glacier

33
Q

Define weathering.

A

The breakdown of the valley rock due to the processed involved with the properties of ice in the glacier

34
Q

What is abrasion?

A

When material inside the glacier and ice scrapes the valley bed and sides, grinding it and causing rock to fall off.

Coarser rock scrapes and rips rock out which causes striations in the glacier.

Smoother material smooths the valley rock.

35
Q

What is rock flour?

A

Extremely small eroded material.

36
Q

What is plucking?

A

When the glacier freezes onto the rock meaning as the glacier moves forward, it pulls the rock and forces it to be ripped off.

37
Q

What is frost shattering?

A

The breaking of rock as water moves into its cracks, it expands as it freezes and shatters the rock.

The cracked rock is called scree.

38
Q

What is nivation?

A

The hollowing of rock due to the presence of ice.

Snow accumulates over the rock, it creates a small hollow due to chemical weather or frost shattering. This causes the rock to disintegrate and form a small hollow.

39
Q

What is compressing flow?

A

A reduction in the gradient of the valley, causing the glacier to slow down.

The ice thickens and compresses.

Erosion is at its maximum

40
Q

What is extending flow?

A

The gradient of the valley increases, making the glacier speed up

The glacier becomes thinner

Erosion is at its minimum

41
Q

What is Basal Flow?

A

Increased pressure on the base of the glacier causes the ice to melt due to the pressure melting point.

The meltwater is a lubricant and allows the glacier to travel at a faster rate.

A surge occurs when this happens at a great rste

42
Q

What is internal deformation?

A

It occurs in the upper zone of a glacier.

The ice crystals orientate themselves in the direction of movement.

They then slide past each other down the valley. It is how crevasses develop.

43
Q

What is rotational flow?

A

When ice pivots around a point in a valley

The pivoting leads to increased pressure and erosion

44
Q

What is creep?

A

When stress builds up in a glacier, it enables it to behave like a plastic.

It flows over obstacles as a mouldable material

45
Q

What is a corrie?

A

An armchair shaped rock hollow, it has a steep wall, tarn and corrie lip.

46
Q

How is a Corrie formed?

A

1) A hollow is formed by nivation

2) Snow deepens the hollow due to chemical weathering and frost shattering

3) As more snow accumulates, a firn us made as the ice is compressed

4) Due to gravity, the glacier begins to move downhill which erodes the hollow more due to rotational slip

5) Plucking occurs at the back wall of the glacier and makes them steep

6) Abrasion deepens the corrie as plucked rock grinds against the base

7) Once the glacier gains enough weight, it moves out if the hollow and any material is deposited to form a corrie lip

8) In warmer temperatures, the glacier may melt to form a tarn

47
Q

What is an Arête?

A

A knife edged ridge formed when two corries errode back to back

Eg) Striding Edge in the Lake District

48
Q

What is a bergschund?

A

A crevasse that forms when a moving glacier separates from the back wall of a Corrie

49
Q

What is a pyramidal peak?

A

When 3 corries errode around a single point it leaves a rock feature between the 3 hollows.

Eg) Matterhorn

50
Q

How does a Rush Moutonnee form?

A

1) As a glacier moved over pertruding bedrock in the valley, it erodes it.

2) As the glacier moves over the rock its weight applies pressure to the base - causing it to melt

3) The meltwater allows the glacier to move over the rock and the uphill part of the rock gets smoothed

4) As the glacier moves, pressure decreases so the meltwater freezes to the back of the rock and plucks it as the ice moves forward, creating cracks

51
Q

What is the formation of patterned ground?

A

1) Hydrostatic pressure increases in the ground as the moisture freezes and rises. This forms an ice lens as they group together

2) Capillary action leads to more moisture joining the ice lens so it gets bigger

3) As the ice grows, it will begin to push up stones in the soil because they have a lower specific heat capacity and smaller sediment will prevent them from falling back down

4) The stones poke out of the ground and the heavier ones may fall due to gravity

52
Q

When will a patterned line form?

A

When the patterned ground process takes place on a slope

53
Q

How do pingos form?

A

They form when there is discontinous permafrost.

Frost heave freezing caused ice lenses which push up from the ground

54
Q

Types of pingos

A

Open System Pingos - occurs in areas of permafrost

Closed System Pingos - occurs in areas of permafrost

55
Q

How is an open system pingo formed?

A

1) When temperatures drop, hydrostatic pressure increases and the moisture in the ground freezes and rises

2) As it rises, it creates a mound in the ground that rises upwards.

3) If the pressure is too great, the ground above can crack and expose the ice, it will melt and leave a lake

56
Q

How is a closed system pingo formed?

A

1) As temperatures decrease, hydrostatic pressure increases and the moisture in the soil freezes and rises (becoming an ice lens) OR a lake can freeze over

2) As permafrost advances, it pushes up the frozen lake/ice lens, forming a mound

57
Q

Describe a U-shaped valley

A

A valley with steep sides and flat bed.

It looks “U” shaped

58
Q

How is a U-Shaped Valley formed?

A

As a glacier moves down a V-Shaped valley, it erodes it, deepening and widening it through plucking and abrasion

59
Q

How are truncated spurs formed?

A

These form when the glacier erodes through interlocking spurs, formed originally by meanders.

The glacier erodes through them, plucking and cutting their curved shapes to straight block-like shapes.

60
Q

What is a hanging valley?

A

A smaller sized valley which overlooks the main channel

61
Q

How is a hanging valley formed?

A

A tributary glacier flower into the main glacier but was cut off as the glacier formed the U-shaped valley

62
Q

Describe how a ribbon lake is formed

A

1) As glacier erodes the valley, if there is soft rock in the bed, it will erode it at a greater rate

2) This can leave a hollow in the bed which is deeper than the rest. Meltwater fills it to become a lake

63
Q

What is a misfit river?

A

A river which flows in a valley which it did not errode.

The river is not proportionate to the size of the valley

Geography (1 decks)

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