Glaciation

Question 1

Name 4 pro glacial landforms

Answer 1

• pro-glacial lakes
• kettleholes
• sandurs (outwash plains)
• Meltwater channels

Question 2

Describe how a pro-glacial lake is formed

Answer 2

• Formed along the front of glaciers and ice sheets where melt water from the glacier becomes impounded with a deposition blocked by glacier ice and bounded by high grounds

Question 3

Describe how kettles are formed

Answer 3

During ice retreat, blocks of dead ice become detached. Sediment builds up around the dead ice and when the eventually melt, a small hollow is formed in which water accumulates to form a lake

Question 4

Describe how a sandur (outwash plain) is formed

Answer 4

What is it?
- a flat expanse of sediment deposited in from of a glacier
How does it form?
-as the melt water streams gradually lose energy due to entering lowland areas, they deposit their material. The largest material is deposited nearest the snout and the finest further a way.

Question 5

Describe how a melt water channel is formed

Answer 5

Melt water on the surface of the glacier melt its way through the glacier to the base through a ‘moulin’. Once the melt water comes out from the base of the glacier in forms a channel in front of to the glacier

Question 6

Name three fluvioglacial landforms

Answer 6

Esker, Kame, Kame terrace

Question 7

Describe how an esker is formed

Answer 7

Subglacial streams carry large amounts of rock debris due to their hydrostatic pressure inside the tunnels. The stream often meanders beneath the glacier, when the glacier retreats, the debris load is deposited at a consistent rate and forms a ridge.

Question 8

Describe what an esker is

Answer 8

A long, narrow, sinuous (widening and meandering) ridge of sand and gravel

Question 9

Describe how a Kame is formed

Answer 9

A meltwater stream emerges into an outwash plain or peri glacial lake at the glacier snout, their velocity falls and energy is lost causing sediment to be deposited.

Question 10

Describe what a Kame is

Answer 10

An undulating mound of sand and gravel deposited on the valley floor

Question 11

Describe how a Kame terrace is formed

Answer 11

During the summer, the valley sides radiate heat. This melts the edge of glacier forming a meltwater stream. This deposits sediment. When the glacier retreats, the sediment will fall to the valley floor, forming a Kame terrace.

Question 12

Describe what a Kame terrace is

Answer 12

A flat, linear deposit of sand and gravel along the valley sides

Question 13

Name 3 peri glacial landforms

Answer 13

Pingo (open and closed), patterned ground, ice wedges

Question 14

Describe how a closed system pingo is formed

Answer 14

The lake insulates the talik preventing it running to permafrost. Water begins to drain from the lake reducing the amount of talik. Pressure from the advancing permafrost allows land (talik) to settle above.
Hydrostatic pressure causes the water to turn to ice. Hydrostatic pressure also pushes the land above causing the land to be disformed.

Question 15

What is talik

Answer 15

Unfrozen ground in a periglacial area that surrounds the permafrost

Question 16

Describe how ice wedges are formed

Answer 16

A thin piece of ice (around 3-4 metres in length) causes a crack in the rock. In the winter, ice freezes and expands. When the temperature rises, the ice melts. More water fills the crack and permafrost freezes it. This process repeats itself until a polygon of ice goes deep into the ground.

Question 17

Describe what an ice wedge is

Answer 17

It is a wedge if ice extending 3-4 metres underground, usually in a polygon shape

Question 18

Describe how patterned ground is formed

Answer 18

Ice wedges form underneath granite. As the ice wedges continue to expand (by 10%) the land above buckles and creates a trough with small mounds. Ice wedges melt causing land to fall in its place. This leaves new mounds in between where the ice wedges used to be.

Question 19

Describe how an open system pingo is formed

Answer 19

Groundwater moves through the ground and eventually finds a weakness in the permafrost. Hydraulic pressure causes the water to rise up through the cracks. As the water gets closer to the surface, the temperature decreases turning into ice. Hydrostatic and hydraulic pressure causes the ice to continue moving upwards. This creates an open system pingo

Question 20

Name 5 macro erosion landforms

Answer 20

U-shaped valley, hanging valley, ribbon lake, pyramidal peak, corrie/cirque

Question 21

Describe how a ribbon lake is formed

Answer 21

Meltwater at the glacier base plays a role, and where PMP is exceeded, the glacier can basically slide encouraging even more erosion.
Differential erosion= some parts of the valley floor are over dependant creating ribbon lakes.

Question 22

Describe how a corrie is formed

Answer 22

Snow accumulates in a hollow. Snow compacts making a neve/firn and glacial ice. Ice becomes too big for the hollow and moves down the slope. It will move in a rotational slip. The hollow deepens through invasion, abrasion and plucking. Freeze thaw shatters rocks above the hollow and delivers shattered rock (scree) to the ice - abrasion. Pressure melting point is often surpassed allowing melting to exist which allows basal slippage. This creates a steep back wall and a hollow known as a corrie.

Question 23

Describe how a pyramidal peak is formed

Answer 23

If three or more corries development on all sides of a mountain a pyramidal peak is formed. The feature has steep sides and several arêtes radiating from the central peak.

Question 24

Name an example of a pyramidal peak

Answer 24

The Matterhorn, Alps

Question 25

Describe how a U-shaped valley?

Answer 25

As the glacier leaves the Corrie it moves down the old river valleys that are V-shaped. As the valley glacier moves down the valley, it plucks material from the valley sides and base. This allows abrasion to occur making the valley deeper and wider. Lateral and ground moraine abrade the valley sides and the floor further. The front of the glacier acts like a bulldozer and shifts and removes the plucked material turning the interlocking spurs into truncated spurs.

Question 26

Describe how a hanging valley is formed

Answer 26

Hanging valleys are created due to different rates of erosion between the main valley and the tributary valleys that enter it along its sides. The floors of the tributary valleys are eroded and deepened by abrasion and plucking at a slower rate than the floor of the main valley, so the difference between the depths of the two valleys steadily increases over time. The tributaries are left high above the main valley, hanging on the edges. In the post glacial, rivers and streams return and enter the main valley by either a series of small waterfalls or a single impressive fall.

Question 27

Name 3 messo erosional landforms

Answer 27

Roche mountonness, crag and tail, knock and lochan

Question 28

Describe how a crag and tail is formed

Answer 28

The glacier erodes soft rock and then reaches a band of hard rock. Once the band of hard rock is reached, pressure builds and pmp is reached enabling the glacier to overcome the hard rock. This causes a rapid decrease in pressure and a fall below pmp. This causes a loss in energy, causing the glacier to drop sediment. This forms the tail of the crag and tail.

Question 29

Describe how a Roche mountonness is formed

Answer 29

The glacier encountered the obstacle, pressure increases and allows melting to occur (PMP exceeded). This allows the ice to melt and basal slippage to occur, rocks trapped in this ice abrade the bedrock. This abrasion on the up-valley sides of the glacier can leave striations as pieces of rock debris with the ice were dragged across the surface under great pressure. Once the Lee side pressure fails and the water refreezes (regelation) and as the ice moved downhill it pulls away masses of rock; plucking the rocks underneath. This leaves a steeper sided, more jagged Lee slope.

Question 30

Describe how a knock and lochan is formed

Answer 30

Alternating Roche mountonness and eroded hollows often containing small lakes

Question 31

Give an example of a crag and tail

Answer 31

The royal mile, Edinburgh

Question 32

Name two micro glacial erosion landforms

Answer 32

Crescentic gouges and striations

Question 33

Describe how crescentic gouges are formed

Answer 33

Plucking

Question 34

Describe how striations are formed

Answer 34

Caused by abrasion

Question 35

Name 5 glacial depositional landforms

Answer 35

Lateral moraine, recessional moraine, terminal moraine, medial moraine and drumlins

Question 36

Name the two theories of how drumlins are formed

Answer 36

Boulton Menzies, shaw theory

Question 37

What are the 4 types of moraine?

Answer 37

Lateral moraine, recessional moraine, terminal moraine, medial moraine

Question 38

Describe how lateral moraine is formed

Answer 38

Debris from freeze thaw weathering falls onto the glacier and then is transported and then deposited at the edge of the glacier when in melts

Question 39

Describe how recessional moraine is formed

Answer 39

Debris is deposited during the interrupted retreat of the glacier, when the glacier is stationary long enough for there to be a build up of material

Question 40

Describe how terminal moraine is formed

Answer 40

Debris is deposited at the maximum extent of the glacier, especially if the snout is stationary and the glacier is in the equilibrium. It will be continuously supplied in the same place.

Question 41

Describe how medial moraine is formed

Answer 41

At the confluence of two tributary glaciers, the lateral moraines join together medial moraine, which is deposited during ice melt and retreat.

Question 42

Describe the boulton menzies theory of drumlin formation

Answer 42

An obstacle gets in the way of the glacier and this leads to deposition on the Lee side. The obstacle is the core of the drumlin and the ground moraine is around it.

Question 43

Describe the shaw theory of drumlin formation

Answer 43

Subglacial meltwater causes channels and bars to the channel which are shaped by the glacier (streamlined)