Glaciation

Question 1

What are glaciers

Answer 1

A glacier is a large ‘river’ (a large quantity of a flowing substance) of ice

Question 2

Where do glaciers form

Answer 2

Glacier form in high land when the climate is cooler and most of the precipitation falls as snow because it’s so cold

Question 3

How do glaciers form

Answer 3

The snow builds up and over a long period of time is compressed into ice. When the glacier is large enough it will slowly move downhill from the pull of gravity and under its own weight

Question 4

What is freeze-thaw

Answer 4

Freeze-thaw is when water seeps into cracks in rocks. The temperature will then decrease causing the water to freeze it expands which puts pressure on the rock. Then when the temperature increased again the frozen water melts and the rock contracts. The process happens over and over again. Each time the rock does this it weakens and it breaks up

Question 5

What happens to the loose rock which breaks up because of freeze-thaw

Answer 5

The loose rock bounces down slope and collects. it is called scree

Question 6

What are the other terms for freeze-thaw

Answer 6

frost-shattering or nivation

Question 7

What is erosion

Answer 7

erosion is when earth materials are worn away and transported by natural forces

Question 8

What are the two ways glaciers erode land

Answer 8

1. Plucking
2. Abrasion

Question 9

Where does plucking occur

Answer 9

Plucking occurs along the base and sides of glaciers

Question 10

How does plucking work

Answer 10

Glaciers freeze onto rock surfaces. When glaciers begin to move downhill they tear pieces of rock away with them

Question 11

Where does abrasion occur

Answer 11

Abrasion occurs along the base and sides of glaciers

Question 12

How does abrasion work

Answer 12

It’s the sandpapering effect of the glaciers and rocks frozen to its base.

When the glacier moves downhill the rocks frozen to the base of the glacier scrape away the land underneath. Causing erosion.

Question 13

What is a corrie

Answer 13

A corrie is a bowl shaped hollow on a mountainside. They formed due to glacial erosion

Question 14

How do corries form

Answer 14

1.At the start of the ice-age the temperatures dropped. Snow acculmilacted in north-facing hollows on mountainsides, where the temperatures were cooler. As the snow built up, it was compressed into ice. Under the glaciers own weight and the force of gravity, the glacier began to move downhill in a rotational fashion.
2. As the glacier did this is plucked rock away steepening the back wall of the hollow. While this was happening abrasion deepened the hollow where the glacier was at its thickest and heaviest.
3. When the glacier moved up and out of the hollow it lost its strength. This left behind a notch of rock at the entrance of the corrie, called a rock lip.

Question 15

What are Aretes

Answer 15

Aretes are knife-edged ridges

Question 16

How are Aretes formed

Answer 16

Aretes are formed when two corries next to each other back into the mountain. This narrows the area of land between them

Question 17

How do Pyramidal Peaks form

Answer 17

Pyramidal peaks form when three or more corrie glaciers erode back to back on a mountainside.

When the corrie glaciers erode their backwalls, they create Aretes. They also narrow the peak between each corrie.

This forms a mountain peak that is roughly pyramidal in shape.

Question 18

What are U-shaped valleys

Answer 18

U-shaped valleys are wide valleys with flat floors and steep sides. They are formed by the same erosional processes that form corries, aretes and pyramidal peaks.

Question 19

How are U-shaped valleys formed

Answer 19

At the start of the ice age precipitation fell as snow. The snow collectd and was compressed into ice. Once it as large enough it became a glacier. Under the glacier’s own weight and the force of gravity the glacier began to move downhill through a pre-existing V-shaped valley. The glacier freezes to the valleys sides. As it began to move again it plucked pieces of rock away from the sides. Rocks frozen to the glacier also scraped away at the land. This helped to truncate the interlocking spurs, steepening the valley sides, widening the valley and straightening it out.

Question 20

How is a terminal moraine formed

Answer 20

Loose rock, soil, gravel etc was pushed forward to the front of the glacier. This would normally form a terminal moraine at the entrance to the corrie. When the ice-age ended the glacier melted. The terminal moraine sealed in the meltwater to form a corrie loch called a tarn

Question 21

What are truncated spurs

Answer 21

Truncated spurs are the flat, steep valley sides of a u-shaped valley

Question 22

How are truncated spurs formed

Answer 22

Before the ice-age valleys were narrow river V-shaped valleys with rounded, gently sloping hills. The foot of the hills formed interlocking spurs. The river wound round because it did not have the erosive power to remove them. Glaciers were far bigger so therefore had more erosive power than rivers. During the ice-age glaciers eroded those interlocking spurs, making them much steeper. Abrasion happened where the rocks frozen to the base and sides of the glacier scraped away at the interlocking spurs in a sandpapering motion. Sometimes the glacier would freeze onto the sprs and then as it started moving downhill it would pluck pieces of rock away. Because of this the ends were removed from the interlocking spurs, truncating them. This gave the sides of the U-shaped valley a steep, flat sided appearance.

Question 23

What are interlocking spurs

Answer 23

Interlocking spurs are areas of land that jjut towards each other