Glaciers T3: Glacial movement

Question 1

Why does a glacier move?

Answer 1

1. Gravity

2. Lubrication

Question 2

Types of glacier and how they move.

Answer 2

1. warm based glacier
   - Move a lot
   - Basal sliding
   - Move as one body
2. Cold based glacier
   - Move a little
   - Fracture
   - No lubrication

Question 3

What are the 4 factors which vary the velocity of the glacier?

Answer 3

1. Thickness: a thicker glacier creates more pressure thus more movement.
2. Temperature: warmer climate means easier deformation, and more meltwater reduces the friction.
3. Bedrock: deformable rock increases basal sliding, also with impermeable rock water is not lost thus increasing the amount of lubricant.
4. Gradient: gravity assists flow.

Question 4

What are kinematic waves?

Answer 4

A bulge on the surface of the glacier due to increased accumulation moves from the accumulation zone to the snout because thicker ice underneath moves slower.

Question 5

What is Basal sliding?

Answer 5

Friction and pressure cause the base of the glacier to melt thus creating a lubricant so the glacier moves.

Question 6

What is internal deformation?

Answer 6

Stress builds up: it behaves with plasticity and flow. It is slow movement between crystals.

Question 7

What is meant by a glacial surge?

Answer 7

Meltwater builds up and causes a sudden increase of flow/ velocity. It can be up to 10 to 100 times quicker than normal.

Question 8

What is extensional flow?

Answer 8

When the gradient increases, the ice then accelerates, tit thins and reduces the amount of erosion.

Question 9

What is compressional flow?

Answer 9

When the gradient reduces, the ice decelerates, thickens and increases the amount of erosion.

Question 10

What is rotational flow?

Answer 10

This occurs in a corrie, ice moving downhill can pivot about a point, increases pressure and consequently the amount of erosion.