2.a Flows of material - Erosion

Question 1

What is plucking?

Answer 1

The water at the bottom of the glacier freezes onto the bedrock and as the glacier moves it pulls debris and pieces of rock with it.

Question 2

At what point on the glacier is plucking most effective?

Answer 2

At the base of the glacier as the mass above will cause meltwater –> which then seeps into the joints

Question 3

What is abrasion?

Answer 3

As the glacier moves across the surface the debris carries is scraped against the valley surfaces causing them to melt away.

Question 4

In abrasion what is the glacial rock worn down to form?

Answer 4

Rock flour

Question 5

How does presence of basal debris affect abrasion?

Answer 5

Abrasion increases with debris until it reaches a point where friction slows down the movement

Question 6

How does debris size affect abrasion?

Answer 6

Larger debris is more effective due to a greater downward pressure being exerted

Question 7

How does hardness of bedrock affect abrasion?

Answer 7

Abrasion more effective when hard rock is moved across weak bedrock –> as if bedrock is more resistant little abrasion occurs

Question 8

How does meltwater affect abrasion?

Answer 8

A layer of meltwater is required for the rocks to slide across the surface

Question 9

How does ice thickness affect abrasion?

Answer 9

The thicker the ice the greater the pressure meaning increased erosion

Question 10

How does removal of fine debris affect abrasion?

Answer 10

to maintain high rates rock flour needs to be removed so larger particles can erode the bedrock

Question 11

What is nivation?

Answer 11

Glacial processes of weathering associated primariy with alternating freezing and thawing weathers away rocks