Different glaciers

Question 1

Valley glaciers

Answer 1

1. confined by valley sides
2. may be outlet glaciers from ice sheets OR fed by snow & ice from 1 or more corrie glaciers
3. dynamic/ active

Question 2

What do valley glaciers follow the course of?

Answer 2

existing river valleys or corridors of lower ground

Question 3

How long are valley glaciers?

Answer 3

10-30km
sometimes 60km (like Pakistan)

Question 4

Ice sheets

Answer 4

1. largest accumulations of ice
2. during last glacial period huge ice sheets covered much of Europe

Question 5

What size are ice sheets?

Answer 5

+ 50,000km^2

Question 6

Name the world’s 2 ice sheets.
And how much of the world’s ice are they?

Answer 6

Greenland & Antarctica
96%

Question 7

How much does the Antarctica ice sheet cover?

Answer 7

13.6mil km^2

Question 8

What is the volume of the Antarctic ice sheet?

Answer 8

30 mil km^3

Question 9

How thick is the Antarctica ice sheet?

Answer 9

at its thickest (East) = 4700m + deep

Question 10

What type of glacier is an ice sheet?

Answer 10

cold-based glacier

Question 11

What type of glacier is a valley glacier?

Answer 11

warm-based glacier

Question 12

Features of a cold-based glacier

Answer 12

• high latitude locations
• low relief
• basal temperature below pressure melting point > frozen to bedrock
• very slow rates of movement often only a few metres a year

Question 13

Features of a warm-based glacier

Answer 13

• high altitude locations
• steep relief
• basal temperature at or above pressure melting point
• rapid rates of movement = 20-200metres/ yr

Question 14

Examples of warm-based glaciers

Answer 14

• Iceland
• Alps
• Himalayas

Question 15

What is basal sliding?

Answer 15

warm-based glacier’s main movement
* glacier slides over bed because of meltwater (surface ice melting)

Question 16

What does basal sliding depend on and why?

Answer 16

• Slippage: slip of glacier between bed due to lower latitudes
• Creep/ regulation: ice melts under pressure and refreezes when pressure’s reduced
• Bed deformation: the sediment deforms under pressure

Question 17

What is internal deformation?

Answer 17

cold-based glacier’s movement (can’t move in basal sliding)
* gravity & pressure of ice in accumulation zone causes ice crystals to slide over eachother
* can result in deep crevasses at the surface

Question 18

What are the 2 elements of internal deformation?

Answer 18

When glacier is on slope (not level surfaces where ice remains intact):
Intergranular flow = individual ice crystals re-orientate & move in relation to eachother
Laminar flow = movement of individual layers within the glacier - often layers of annual accumulation

Question 19

What factors influence the movement of glaciers?

Answer 19

• Thickness
• Gravity
• Gradient
• Internal temperatures of ice
• Glacial budget