Glacial Processes

Question 1

What type of weathering is freeze-thaw weathering?

Answer 1

Physical/mechanical weathering

Question 2

What type of environments is freeze-thaw weathering commonly found?

Answer 2

Mountainous/Cold environments

Question 3

What is the name of the debris created by freeze-thaw weathering?

Answer 3

Scree

Question 4

Define weathering

Answer 4

Weathering is the break-down of rock in situ (ie no movement) by the process of the weather. The glaciers do not have anything to do with this process. This happens on the slopes above the glacier.

Question 5

Define erosion

Answer 5

The wearing away and removal of the land by flowing water, ice or wind.

Question 6

What is abrasion?

Answer 6

Abrasion is where rocks at the bottom of the glacier act like sandpaper - grinding over the bedrock. This can polish the rocks or create sharp grooves called striations.

Question 7

What are striations?

Answer 7

Sharp grooves created by the process of abrasion.

Question 8

What is plucking?

Answer 8

Plucking is where a glacier moves over an area of rock. Due to friction, the glacier melts and water seeps into cracks around the rocks below. The water refreezes and the rock effectively becomes part of the glacier and is ripped out when the glacier continues to move forward.

Question 9

What is the name of young ice?

Answer 9

Firn/Neve

Question 10

Explain the process of freeze-thaw weathering

Answer 10

1. Joints in the rock fill with water.
2. The water freezes and expands and over time this splits the rock apart.
3. Repeated freezing and thawing widens the crack and eventually bits fall off to create scree.

Question 11

How does a glacier move?

Answer 11

1. Gravity
2. Basal Flow: It slides over the underlying rock on a film of meltwater in a process called basal flow.
3. Internal deformation.

Question 12

What is internal deformation?

Answer 12

The ice moves as if it were plastic, oozing along, speeding up and slowing down in response to changes in the gradient of the slope below.

Question 13

Where does the initial accumulation of snow take place?

Answer 13

Shady north-facing hollows in upland areas (where winter snow can survive without melting through the summer months).

Question 14

Explain how snow is converted into glacier ice over time.

Answer 14

1. Snow falls in layers.
2. Over time the layers become compressed - as the air is squeezed out of the layers.
3. Firn or neve is formed.
4. As the weight of the snow and ice above increases all of the air is squeezed out leaving only ice.

Question 15

What is basal flow?

Answer 15

A film of meltwater develops due to pressure melting at the base of the glacier which is basal flow.

Question 16

What is bulldozing?

Answer 16

Ice pushes material of all shapes and sizes as it moves slowly forward (at the snout)

Question 17

What is glacial outwash?

Answer 17

Material, mainly sand or gravel, deposited by meltwater streams in front of, and underneath, a glacier. The material is sorted and rounded by water action.

Question 18

Which erosional processes has reduced the size of outwash material?

Answer 18

Attrition

Question 19

Where would you expect to find the fine material deposited by the glacier - closest or furthest away from the glacier?

Answer 19

Furthest from the glacier.

Question 20

What is till?

Answer 20

An unsorted mixture of sand, clay and boulders carried by a glacier and deposited as ground moraine over a large area.

Question 21

What is moraine?

Answer 21

Frost-shattered rock debris and material eroded from the valley floor and sides, transported and deposited by glaciers.