Glacial landscapes

Question 1

Abrasion

Answer 1

Rocks carried along by the river wear down the river bed and banks.

Question 2

Arête

Answer 2

a sharp, knife like ridge formed between two corries cutting back by processes of erosion and freeze-thaw weathering.

Question 3

Bulldozing

Answer 3

Ice pushes materials of all shapes and sizes as it moves slowly forward.

Question 4

Corrie

Answer 4

Armchair-shaped hollow in the mountainside formed by glacial erosion, rotational slip and freeze-thaw weathering. This is where the valley glacier begins. When the ice melts, it can leave a small circular lake called a tarn.

Question 5

Drumlin

Answer 5

A hill made of glacial till deposited by a moving glacier usually elongated or oval in shape, with the longer axis parallel to the former direction of ice.

Question 6

Erratic

Answer 6

Rocks that have been transported and deposited by a glacier some distance from their source region.

Question 7

Freeze-thaw weathering

Answer 7

A process of erosion that happens in cold areas where ice forms. A crack in the rock fills with water which freezes and expands and puts pressure on the rock causing parts to break.

Question 8

Glacial trough

Answer 8

a river valley widened and deepened by the erosive action of glaciers; it becomes U-shaped instead of V-shaped.

Question 9

Hanging valley

Answer 9

A tributary valley to the main glacier, too cold and high up for ice to be able to move easily. It therefore was not eroded as much as the main valley.

Question 10

Moraine

Answer 10

Frost-shattered rock debris and material eroded from the valley floor and sides, transported and deposited by glaciers

Question 11

Outwash

Answer 11

Material, usually sand or gravel, deposited by meltwater streams in front of and underneath a glacier. The material is sorted and rounded by water action.

Question 12

Plucking

Answer 12

A type of erosion where melt water in the glacier freezes onto rocks, and as the ice moves forward it plucks or pulls out large pieces along the rock joints.

Question 13

Pyramidal peak

Answer 13

Where several corrie cut back to meet at a central point the mountain takes the form of a steep pyramid.

Question 14

Ribbon lake

Answer 14

A long narrow lake found in glaciated valleys formed in locations where the glacier had more erosive power eg in areas of softer rock, where the valley gradient temporarily steepened or a tributary glacier joined the main valley.

Question 15

Rotational slip

Answer 15

This occurs when the ice moves in a circular motion. This process can help to erode the hollows in the landscape, and deepen hollows into bowl shapes.

Question 16

Till

Answer 16

An unsorted mixture of sand, clay, and boulder carried by a glacier and deposited as ground moraine over a large area.

Question 17

Truncated spur

Answer 17

A former river valley spur that has been sliced off by a valley glacier, forming cliff-like edges.

Question 18

What is an interglacial period?

Answer 18

A time when temperatures are warmer for a certain period.

Question 19

Describe the formation of a glacier:

Answer 19

Glaciers form when snow remains in the same area year-round, slowly transforming into ice.
Each year, new layers of snow bury and compress into previous layers.
This compression forces the snow to re-crystallize, forming grains similar in size to grains of sugar.
Gradually the grains grow larger and the air pockets between the grains gets smaller, causing the snow to slowly compact and increase in density.
After about two winters, the snow turns into firn/neve - a middle state between snow and glacial ice.

Question 20

How is subglacial material transported?

Answer 20

Some material is plucked or abraded from the bedrock so is carried under the ice.

Question 21

How is englacial material transported?

Answer 21

Some material falls into the crevasses and is transported inside the ice.

Question 22

How is supraglacial material transported?

Answer 22

Some material falls onto the ice from surrounding mountain sides so is carried on top.

Question 23

Basal slip

Answer 23

Meltwater beneath a glacier enables it to slide forward as a mass by a few metres a year.

Question 24

Explain the formation of a corrie:

Answer 24

1. Snow accumulates in depressions high up, predominantly on north facing slopes.
2. Over time the snow becomes glacial ice and there is more ice than the depression can hold and some of it starts to flow to lower levels.
3. Ice becomes frozen due to the back of the hollow and plucking occurs as blocks of rock are pulled away as the ices moves downhill. This makes the back wall steeper and these rock fragments become incorporated into the glacier.
4. Freeze that weathering occurs at the top of the slope producing scree which becomes incorporated into the glacier.
5. The hollow deepens where the ice is thickest due to abrasion. Rock debris acts as tools to wear away the bottom of the hollow.
6. There is less erosion at the front where the glacier leaves the corrie hollow to flow down the valley; a rock lip forms here as a result of less powerful erosion.
7. When all the ice as melted a tarn forms.

Question 25

Lateral moraine

Answer 25

A ridge of material that runs along the edges of a glacial trough close to the valley side. As ice melts and the glacier gets smaller, this material is slowly lowered to and deposited on the valley floor.

Question 26

What is the source of the material in lateral moraine?

Answer 26

Freeze thaw weathering, high on the valley sides causing shattered blocks of rock to fall on the glacier below.

Question 27

Medial moraine

Answer 27

When two glaciers meet, two lateral moraines merge together to form very large ridge of rock debris.

Question 28

Ground moraine

Answer 28

The material that gets lodged and deposited underneath the glacier.

Question 29

Terminal moraine

Answer 29

The enormous ridge of material that gets bulldozed by the snout of the glacier. They allow us to see how far the ice advanced during the last ice age.