Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HDSO Glaciers > AS Glaciers Videos > Flashcards

AS Glaciers Videos Flashcards

1
Q

What is a glacier?

A

A glacier is a mass of ice moving down a valley.

As snow falls on a surface, it begins to accumulate into a mass.

The snowflake structure has air trapped inside it.

As more snow accumulates, the weight exerted on the bottom of the snow compresses the mass, forcing the air out and making a compact structure called firn.

Over time the air is fully pressed out leaving a compressed block of ice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two types of glaciers?

A

Temperate glaciers and polar glaciers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are temperate glaciers?

A

Glaciers which melt in the summer slightly when temperatures rise.

The meltwater makes the glacier melt due to basal flow.

It is therefore likely to erode at a greater rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is basal flow?

A

The flow of a glacier down a valley because of the meltwater underneath the glacier (slipping).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are polar glaciers?

A

Do not melt at all because the temperature is always 0 degrees.
They are therefore less likely to erode as they move slower (no meltwater).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do polar glaciers move?

A

They do not have meltwater, so they move by internal deformation.

Ice crystals orientate themselves in the direction of flow and slide past each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Glacial zones

Why do different parts of the glacier behave differently?

A

The upper zone has less pressure on it and hence no meltwater.
It moves by internal flow and faster as there is less friction.

The lower zone has more pressure on it and so has meltwater.
It moves by basal flow and slower because of the friction from the bedrock.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the transfers in the glacial budget?

A

The flows of ice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the outputs in the glacial budget?

A

Ablation, evaporation and sublimation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is ablation?

A

The melting of ice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is sublimation?

A

The direct conversion of solid to gas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What the main types of glacier flow?

A

Compressing flow

Extending flow

Basal flow

Internal deformation

Rotational flow

Creep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
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 max.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is extending flow?

A

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

The glacier becomes thinner.

Erosion is at a minimum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is basal flow?

A

This happens when increased pressure on the base of the glacier causes the ice to melt into meltwater.

The meltwater serves as a lubricant and allows the glacier to travel down the glacier at a faster rate.

A surge occurs when this happens at a greater rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is internal deformation?

A

This occurs in the upper zone of the glacier.

The ice crystals orientate themselves in the direction of movement.

They slide past each other down the valley.

This is how crevasses develop.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is rotational flow?

A

When the ice pivots around a point in the valley.

The pivoting leads to increased pressure and erosion which can form landforms such as corries.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is creep?

A

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

It flows over obstacles as a mouldable material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the lake called left in a corrie?

A

A tarn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a corrie?

A

An armchair shaped rock hollow in the valley.

It has a steep wall, tarn and corrie lip.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is an arete?

A

Occurs when two corries on opposite sides of a valley/ ridge begin to erode into each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is a pyramidal peak?

A

When 3 corries erode into each other and around a single point.
This leaves a rock feature pointing upwards between the 3 hollows.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does a Roche Moutenee form?

A

As a glacier moves over protruding bedrock in the valley. It erodes as it does so.

As it moves over, it applies a lot of pressure on the base because it’s moving uphill.

This causes the base to melt creating meltwater.

The meltwater allows the glacier to move over the rock. It stays as meltwater due to such pressure.

The uphill part of the rock is getting smoothed.

After it has moved uphill pressure decreases as less energy is needed to travel.

This causes the meltwater to freeze again as there is not the presence of the pressure.

The frozen water then freezes to the back of the rock and plucks it as the ice moves forward, leaving cracks in the back.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a U shaped valley?

A

This is a valley with steep sides and a flat bed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

When do U shaped valleys form?

A

When the glacier moves down the valley.

It erodes the valley, deepening and widening it as it does so by abrasion and plucking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are truncated spurs?

A

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

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is a hanging valley?

A

This is a smaller valley which overlooks the main channel.

It was a tributary which flowed into the channel, but has now been cut off as the glacier formed the u-shaped valley.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a ribbon lake?

A

This occurs when the glacier erodes the valley.

If there is a soft rock in the bed, it will erode it at a greater rate.

This can leave a hollow in the bed which is deeper than the rest of the bed.

Water can fill it from meltwater streams and form a lake.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are misfit rivers?

A

This is a river which flows in a valley which it did not erode.

The river’s erosive power is not proportionate to the size of the valley.

It is normally a meltwater stream flowing after the glacier has eroded the valley.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is till?

A

Till is unsorted sediment in the glacier valley.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the two types of till?

A

Lodgement till

Ablation till

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is lodgement till?

A

Till deposited from a moving glacier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is ablation till?

A

Till deposited from a melting glacier

34
Q

What is moraine?

A

Glacial till that has been sorted by size.

35
Q

What is lateral moraine?

A

This is moraine located on the sides of the glacier.

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

That sediment is then trapped in the glacier.

36
Q

What is ground moraine?

A

Moraine located at the base of the glacier.

This happens when the material is picked up by the moving glacier.

37
Q

What medial moraine?

A

A line of moraine that is 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 new middle.

38
Q

What is terminal moraine?

A

Deposited moraine when the glacier has reached its furthest point and stopped.

The glacier deposits the sediment.
It then retreats.
The deposited sediment shows the furthest deposited sediment.

39
Q

What is recessional moraine?

A

Lines of moraine deposited and sorted as the glacier retreats.

As it retreats, the glacier leaves behind lines of deposited moraine each time it has melted.

40
Q

What is a drumlin?

A

A landform of shaped moraine.

41
Q

When do drumlins form?

A

As the glacier meets the moraine, it begins to travel over it.

It does not entrain the moraine because it does not have enough energy and can’t erode the resistant rock located in the moraine.

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

42
Q

What is a meltwater channel?

A

A stream/ river that flows down the valley which originates from the glacier’s meltwater.

43
Q

What are the types of meltwater channels?

A

Subglacial
Ice marginal
Proglacial

44
Q

What is a subglacial channel?

A

Meltwater channels that flow under the glacier at the base.

They form due to increased pressure.

45
Q

What is an ice marginal channel?

A

Meltwater channels that flow along the sides of the glacier.

They are located between the glacier and valley.

They form due to increased pressure.

46
Q

What are proglacial channels?

A

Meltwater channels that flow in front of the glacier.

They form due to rising temperatures.

47
Q

Characteristics of meltwater streams

A

Meltwater streams have more erosive power compared to normal rivers because they flow faster due to the glacier’s pressure.

The meltwater channel sorts material as it gets deposited. Large particles are deposited earlier and smaller particles later.

They can also be braided. If the channel loses its energy it will dump all its energy.

48
Q

What is a glacial overflow channel?

A

This is a stream caused by the meltwater from the glacier, it has a lot of erosive power.

49
Q

How do glacial overflow channel form?

A

The meltwater is obstructed by an object in the valley.

The meltwater builds up behind the object and forms a proglacial lake.

As the proglacial lake’s size increases, pressure increases until the water can burst past the object and erode it away.

The water now rushes forward at a great rate throughout the valley. it has a lot of erosive power and leaves a gorge.

50
Q

What is an outwash plain?

A

The flat expanse of sediment deposited in front of a glacier.

51
Q

How does an outwash plain form?

A

The meltwater carries sediment away from the snout as the meltwater retreats.

As the stream carries the sediment, they get deposited when it loses energy. The sediment then gets deposited into sections.

Gravel is deposited first and clay last.

52
Q

What is an esker?

A

A sinuous trail of deposited material from a subglacial channel.

It shows the channels course.

53
Q

How does an esker form?

A

A subglacial stream forms due to increased pressure from glacier.

The channel carries sediment in the glacier and also entrains sediment too.

When the glacier retreats, the subglacial stream stops flowing because the hydrostatic pressure from the glacier is lost.

It deposits all its material now because it doesn’t have the energy to carry it.

It is dumped in the path of where the channel was in. a long line.

54
Q

What is a kame?

A

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

55
Q

How do kame’s form?

A

Rock fall from the valley falls on top of the glacier. The rocks/ sediment then fall into the crevasses in the glacier.

As deglaciation occurs, the crevasses move down closer and closer to the base as the glacier melts.

When they reach the valley bed once the glacier has almost melted, they are dumped on the bed as a mound of sediment.

56
Q

What is a kame terrace?

A

A deposited mound of sediment at the sides of the valley.

57
Q

How does a kame terrace form?

A

Pressure between the valley sides and glacier forms a ice marginal channel/ lake

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

The ice marginal lake/ channel is not flowing so it deposits the material.

When the glacier retreats it leaves the sediment at the valley sides.

58
Q

What are delta kames?

A

Kames that form in a proglacial lake.

59
Q

How do delta kames form?

A

A subglacial channel is formed from the glaciers pressure.

It entrains the material and transports it downstream.

As the subglacial channel meets the proglacial lake, it looses its energy and therefore deposits sediment.

60
Q

What is a varve?

A

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

The material gets deposited by a subglacial channel.

61
Q

How does a varve form?

A

In the winter, less sediment is deposited because there is less meltwater melting.

Then, only smaller particles can be entrained and deposited by the subglacial channel. The rest stays in the glacier.

In the summer, more sediment is deposited and bigger material is deposited. This is because higher temperatures produce more meltwater which entrains more and larger sediment because it has more energy.

This happens year after year and builds up layers of the different sized sediment deposited by the channel.

62
Q

What is a kettle hole?

A

A small lake formed from melted dead ice in the valley.

63
Q

How do kettle holes form?

A

The glacier begins to retreat. It may leave behind dead ice.

The meltwater from the glacier deposits sediment around the dead ice.

Over time, sediment builds around the dead ice.

As temperatures increase, the dead ice melts and a small lake is created.

64
Q

What is permafrost?

A

Permanently frozen ground in a glacial environment.

It must be frozen for 2 years.

65
Q

What are the types of permafrost?

A

Continuous permafrost

Discontinuous permafrost

Sporadic permafrost

66
Q

What is continuous permafrost?

A

Permafrost which covers all of the ground. It reaches very deep levels.

67
Q

What is discontinuous permafrost?

A

Permafrost which does not cover all of the ground and is separated out.

The active layer melts easily.

68
Q

What is sporadic permafrost?

A

Permafrost in very isolated spots with little surface area and little depth.

The active layer melts easily.

69
Q

What is the process of solifluction?

A

When the active layer thaws in warmer temperatures, the ice thaws and turns to water, which lubricates the surface.

The reduces the friction between particles, leading them to fall downslope.

70
Q

Describe the formation of a patterned ground

A

As hydrostatic pressure increases in the ground, the moisture in the ground begins to freeze and rise. This forms an ice lens as they group together.

Capillary action leads to more moisture joining the ice lens to make it even bigger.

As the ice lens grows, it will begin to push stones up located in the soil that are above it. This is because the stones have a lower specific heat capacity than the ice lens, so they form around them.

Smaller sediment in the soil will filter into the gap left by the rising soil, preventing it from falling back down.

The stones now poke out of the ground. The larger ones. may fall because of gravity, causing them to roll down. The finer sediment is left as the highest part of the soil.

71
Q

What are patterned lines?

A

If the patterned grout process takes place on a slope, a patterned line will form.

Stones can roll down the slope and gather as a straight line at the bottom.

72
Q

What are ice wedges?

A

Gaps in the permafrost made of ice.

They are formed by ground contraction.

73
Q

How do ice wedges form?

A

Frozen ice that is located inside a crack in the ground occupies space.

In warmer temperatures, the ice in a crack will melt and turn into water.

Because ice occupies more space, more water from the thawed active layer fills the crack.

In colder temperatures later on, the water will freeze. Due to the hydrogen bonds in ice it occupies 9% more space, so the crack gets bigger to fit the ice.

This forms a wedge as it happens again and again.

74
Q

How do pingos form?

A

When there is discontinuous permafrost.

Frost heaving freezing causes ice lenses which push up the ground and can also form lakes.

75
Q

What two types of pingos are there?

A

Open system pingos (occur in areas of discontinuous permafrost).

Closed system pingos (occur in areas of permafrost).

76
Q

How do open system pingos form?

A

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

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

If the pressure in the mound is too great, the ground above the ice lens can crack and expose the ice. It will melt and leave a lake.

77
Q

How do closed system pingos form?

A

As temperatures decrease, the hydrostatic pressure increases and the moisture in the soil freezes and rises, becoming an ice lens. Or, a lake can freeze over.

As permafrost advances, it pushes up the frozen lake or ice lens, hence forming a mound.

78
Q

Formation of a corrie

Formation of hollow

A
  1. A hollow is formed by nivation (erosion of the ground beneath and at the sides of a snow bank, mainly as a result of alternate freezing and thawing)
  2. The snow deepens the hollow due to chemical weathering and frost shattering.
  3. As more snow accumulates, firn is made and then a glacier as ice is compressed and air travels out.
  4. The hollow now has a gradient. As the glacier moves downhill, it erodes the hollow more.
  5. The glacier will then begin to pivot around a point in the hollow. Rotational flow occurs here, further deepening the hollow due to more erosion.
  6. Plucking occurs at the base of the glacier due to the weight of the glacier pushing it down to pivot around the hollow.
79
Q

Formation of a corrie

Formation of bergshrund

A
  1. A bergshrund can form at the top of the glacier due to the weight of the glacier pushing it down to pivot around the hollow.
80
Q

Formation of a corrie

Formation of corrie lip.

A
  1. Once the glacier gains enough weight, it tries to move uphill out of its hollow. When it does, it loses energy and deposits any material it is carrying. This is deposited adjacent to the hollow and makes a corrie lip.
81
Q

Formation of a corrie

Formation of tarn

A
  1. In warmer temperatures, the glacier may melt and a lake called a tarn is formed. it is dammed by the corrie.

HDSO Glaciers (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions