Glaciation

Question 1

Where is ground moraine in a glacier?

Answer 1

Under the glacier

Question 2

Where is lateral moraine in a glacier?

Answer 2

At the sides

Question 3

Where is medial moraine in a glacier?

Answer 3

On top of and in the middle of a glacier

Question 4

Where is terminal moraine in a glacier?

Answer 4

At the snout (end) of a glacier

Question 5

Name factors which affect the rate at which the glacier moves (basal sliding)

Answer 5

The type of rock the glacier is flowing over
The amount of water flowing under the glacier - this acts like a lubricant and speeds up flow as it decreases rock friction.
Glaciers move faster when it is warmer and slower when it is colder

Question 6

What is Abrasion?

Answer 6

When rocks and stones become embedded in the base and sides of the glacier. These get rubbed against the bedrock at the bottom of the glacier and rock faces at the sides of the glacier as it moves. This causes the wearing away of the landscape as the glacier behaves like sandpaper. It leaves behind smooth polished surfaces.

Question 7

What is plucking?

Answer 7

Occurs when the stones are pulled from the ground or the rock face and it happens as the glacier moves due to gravity - leaving behind a rough jagged landscape.

Question 8

What is freeze thaw?

Answer 8

Physical weathering which is caused by the effects of temperature on rocks. This causes the rock to break apart, assisted by water. The main freeze thaw occurs when water gets into cracks, freezes and causes the rock to crack.

Question 9

What is meant by weathering?

Answer 9

Process where rock is dissolved

Question 10

Name a factor affecting the erosive power of a glacier

Answer 10

The more material which is carried under a glacier, the more power it has.

Question 11

Explain, in detail, the formation of a corrie

Answer 11

Snow collects in a hollow. As it falls it becomes compacted and compressed to form neve. This neve becomes glacier ice over time. Erosion and weathering cause the hollow to become bigger. Gravity encourages this ice to move. Rotational slip is when ice pulls away from the back wall creating a crevasse. Plucked debris from the back wall results in further erosion through abrasion, deepening the corrie. Some of this debris is deposited in the corrie lip. This creates an armchair shaped hollow with a steep back wall. When the corrie ice melts, a circular lake is often formed at the bottom of the hollow - known as a tarn.

Question 12

How does a glacier move?

Answer 12

Snow falls and compacts to form neve. The snow is compacted after many years to form ice. This is the zone of accumulation. The base of the glacier slides down hill; basal sliding.

Question 13

What is a fluvioglacial landform?

Answer 13

Those created by the work of meltwater streams in front of an often retreating glacier

Question 14

Describe the formation of a Kettle Lake/Kettle Hole

Answer 14

When glaciers melt, ice chunks fall off. These are mostly covered by fluvioglacial material from the outwash plain.
As ice melts and outwash sediment settles huge depressions are created
The depression is an underlying impermeable layer, where can collect to form a kettle lake

Question 15

Describe the formation of a kame

Answer 15

When glaciers retreat after melting, cracks appear and are filled with meltwater
Material within becomes sorted with the heaviest deposited at bottom
Deposits left behind form bumpy mounds of sand/gravel
Ice retreats, leaving this mound
Unsupported this usually collapses

Question 16

Describe the formation of a kame terrace

Answer 16

Kame terraces are composed of sands and gravels, but form along the sides of a glacier rather than at the snout
They are formed by the actions of meltwater streams that flow along the sides of the ice, trapped against it by the valley walls
As the valley walls warm up in summer the warm rock helps to melt the ice nearest to it, forming a long depression or trough along which meltwater flows

Question 17

Describe the formation of an esker.

Answer 17

Are produced as a result of running water. Linear mounds of sand and gravel - snakes across land.
As glacier melts, sub-glacial streams flow, deposit load. Eskers consist of sorted material, where streams deposit largest load first.
Glacier retreats - deposited sediment in the channel to land surface where it forms a linear mound or hill, parallel to the path of original

Question 18

Describe the formation of a drumlin

Answer 18

Elongated hills of deposits formed when ice is moving
Glacier carries moraine downhill
Decreased power due to melting
Amount of material deposited goes down
A small obstacle may act as a trigger point
Steep ‘stoss’ slope faces upstream and the ‘lee’ is the gentle longer axis of the drumlin - indication of the direction of the glacier
Reshaped by further ice movement after it was deposited

Question 19

How are all fluvioglacial features formed?

Answer 19

By meltwater from the glacier due to a change in temperature. They sort the deposits from the retreating glacier.

Question 20

How are all erosional features formed?

Answer 20

When the glacier is still frozen so there is still ice to allow plucking and abrasion to occur.

Question 21

Bergschrund Crevasse

Answer 21

A crack which appears between the moving ice of a glacier and the non moving or stagnant ice of a cliff or mountain

Question 22

Explain the formation of an arête

Answer 22

A narrow, knife-edged ridge where two corries have eroded back to back.
That is when the back walls of a corrie have been eroded back so far that only a narrow ridge separates them

Question 23

Explain the formation of a U-Shaped Valley

Answer 23

Have steep sides and a wide, flat floor
Straight and deep
Formed in v-shaped valleys which during the ice age have been filled by a large glacier
Glacier has deepened, straightened and widened the valley by plucking and abrasion
Existing interlocking Spurs truncated - truncated Spurs

Question 24

Explain the formation of a pyramidal peak

Answer 24

Have a sharp summit and steep slopes in at least three sides

Formed where three or more corries erode back so far that they produce aretes with a pyramidal peak in between

Question 25

Terminal Moraine

Answer 25

Material transported by the glacier
Marks the furthest extent of the ice, material is deposited as the glacier begins to melt
Moves material from zone of accumulation to zone of ablation - melting point
Material added through process of bulldozing - material pushed down the valley by the glacier
Made up of unsorted rocks, boulders, stones, pebbles etc as glacier has energy to move material of all different sizes

Question 26

Outwash plain

Answer 26

When meltwater emerges from the snout - loses energy
Material being carried is deposited - largest first - forms an alluvial fan - when these merge, this causes an Outwash plain to form
Finest material carried first as sediment is sorted by size
Sediment laid down during flooding and higher discharge - summer

Question 27

When is a tarn formed?

Answer 27

When corrie ice melts, a circular lake is often formed at the bottom of the hollow

Question 28

Scree Formation

Answer 28

Water seeps into cracks in bare rock faces
Water freezes and as it does expands in volume
Ice then melts and pressure is released
This happens repeatedly
Eventually the rock crumbles and the loose rock tumbles to the bottom of the slope where it is sorted by gravity