Glaciation & Avalanches

Question 1

When was the last ice age in Britain?

Answer 1

18,000 years ago and it retreated 4 times

Question 2

Name the features of a glacier

Answer 2

It consists of inputs, transfers (flows), stores and outputs

Question 3

How is a glacier formed?

Answer 3

1. Snow flakes accumulate in a hollow in the mountains
2. Each year a layer of snow builds up, some melts in the summer
3. As the snow continues year after year, the weight begins to compress the layers of snow
4. The snow being compacted and compressed has all the air squeezed out of it
5. The compression turns the snowflakes into denser layer of glacial ice
6. The lowest layers of snow will be so compacted that they form ‘rock-like ice’
7. Snow will continue to build up on top of this glacial ice
8. As long as temperatures remain low accumulation will occur
9. The now heavier glacier will move down the hillside eroding the surface beneath it
10. When the end of a glacier reaches a lower and warmer altitude of will melt (ablation)

Question 4

Name a famous glacier

Answer 4

The Mer de Glacé in the French Alps

Question 5

What is frost shattering?

Answer 5

The water gets into cracks in the rock and freezes. In doing this the water expands and makes the cracks in the rock larger until it splits

Question 6

What is abrasion?

Answer 6

The material carried no the glacier (moraine) wears away the valley bed

Question 7

What is plucking?

Answer 7

The water at the bottom of a glacier freezes onto rocks on the valley base. As the glacier moves the rock is pulled away from the valley base

Question 8

How is a Corrie formed?

Answer 8

The snow collects in a hollow on the side of a mountain. Over time further snow collects in the hollow. This extra weight compressed the snow underneath turning it into ice. The hollow is deepened but the processes of plucking and abrasion. This leads to an ‘armchair’ shape and causes a ‘rock lip’ to be formed.

Question 9

How are pyramidal peaks formed?

Answer 9

When three or more corries cut back into the same mountain

Question 10

What is an arête?

Answer 10

A ridge between two corries and sometimes referred to as ‘knife edge’

Question 11

What is a drumlin?

Answer 11

Formed of till. They are elongated features that can reach a kilometre of more in length, 500m or do in width and over 50m in height

Question 12

What is a moraine?

Answer 12

The material that a glacier erodes and then carries

Question 13

What is a lateral moraine?

Answer 13

The material carried at the top of the glacier but at the sides

Question 14

What is recessional moraine?

Answer 14

Marks interruptions in the retreat if a glacier

Question 15

What is terminal moraine?

Answer 15

Found at the snout and mat,s the maximum advance of a glacier

Question 16

What is ground moraine?

Answer 16

Dragged beneath the glacier and forks part if the valley floor

Question 17

What is an erratic?

Answer 17

A boulder that is different to the bedrock on which it is sitting. They have been transported and deposited by a glacier. Therefore erratics are useful indicators of patterns of former ice flow

Question 18

Name some natural causes of an avalanche

Answer 18

Heavy snowfall - sometimes tin snow melts and then freezes again. This forms a slide surface. Snow that falls on the slide surface slides down it

Earthquakes - cause large amounts of snow to move down a slope

Question 19

Name some human causes of avalanches

Answer 19

People skiing or snowboarding

Question 20

How do you protect against avalanches?

Answer 20

Build wooden fences on a slope to hold back the snow
Trees hold the snow pack together and break up smaller avalanches
Roads a buildings that are at risk from avalanches can have shires built to help protect them

Question 21

What is an ice age?

Answer 21

A period of time when ice covers much of the land

Question 22

What is an interglacial?

Answer 22

A period of time between one ice age and another. We are in an interglacial period presently

Question 23

What are ice sheets?

Answer 23

Continuous sheets of ice and can be very thick

Question 24

What are ice bergs?

Answer 24

Huge block of ice that floats in the ocean

Question 25

What is a glacier?

Answer 25

A landform made of ice that moves over the land. Sometimes they are referred to as ‘rivers of ice’.

Question 26

How much of the earth was covered in the last ice age?

Answer 26

30% of the earth