5.3: The glacier landform system

Question 1

Name the 5 process’s of glacial erosion

Answer 1

1. Abrasion
2. Plucking
3. Fracture and Traction
4. Dilation
5. Meltwater erosion

Question 2

How does abrasion contribute to glacial erosion?

What features does it create

Answer 2

Abrasion by individual clasts (stones) which leads to micro-features such as striations and chatter marks. Additionally rock flour (size under 0.1mm in diameter) polishes the underlying rocks by ‘sandpaper’ action

Question 3

How does Plucking contribute to glacial erosion?

Answer 3

A type of erosion where melt water in the glacier freezes onto rocks, and as the ice moves forward it plucks or pulls out large pieces along the rock joints.

Question 4

How does Fracture and Traction contribute to glacial erosion?

Answer 4

Occurs as a result of the crushing effect of the weight of moving ice passing over the rock and variations in pressure lead to freezing and thawing of the meltwater (basal melting) which aids the plucking process

Question 5

How does Dilation contribute to glacial erosion?

Answer 5

where the variable weight of glacier ice on top of bedrock can cause fractures to open up, expand and extend deeper.

Question 6

How does Meltwater Erosion contribute to glacial erosion?

What are the 2 parts to it?

Answer 6

Can be both mechanical (similar to fluvial erosion) and chemical, whereby the glacial meltwater dissolve minerals and carry away the solutes, especially in limestone rocks

Question 7

Define Glacial debris entertainment

State the 2 ways it can occur in your answer

Answer 7

Entrainment is the incorporation of debris on to or into the glacier from supraglacial or subglacial sources

Question 8

State where debris will come from if it is Supraglacial debris entertainment

Answer 8

Sources include
1. material falling from hillsides
2. material being washed or blown onto the glacier
3. atmospheric fall out like volcanic ash (often seen in iceland)

Question 9

State where debris will come from if it is
Subglacial debris entertainment

Answer 9

Sources include
1. material eroded from the glazier bed and valley walls
2. material frozen to the base from subglacial streams
3. englacial material that has worked its way through the glacier or ice sheet

Question 10

For ice sheets most debris is transported …? via the basal layer

Answer 10

subglacially

Question 11

For …? glaciers there is more transport by englacial and supraglacial debris as a result of more frequent contact at their …? margins.

Answer 11

1. valley
2. lateral

Question 12

As rocks are transported they come into …? with each other and are ground down (comminuted) by a process similar to river …?

Answer 12

1. contact
2. attrition

Question 13

Glacial sediment transportation occurs horizontally and ..? through glaciers, through the movement of the ice itself, …? transporting sediment through the glacier drainage system or by glacial …? of sediments.

Answer 13

1. vertically
2. meltwater
3. deformation

Question 14

What happens during glacial deposition?

Answer 14

It occurs when material is released from the ice at the margin or the base of a glacier

Question 15

Name 2 deposition mechanisms

Answer 15

Deposition mechanisms include;
- release of debris by melting or sublimation
- lodgement of debris by friction
- deposition of material from melt water
- the disturbance and remodelling of previously deposited sediments

Question 16

Deposition may occur directly on the …? or sediment may be released into …?

Answer 16

1. ground
2. meltwater

Question 17

What size feature constitutes a Macro-scale feature

Answer 17

Macroscale features of glacial erosion are those features that are 1 km or greater in dimension

Question 18

What size feature constitutes a Meso-scale feature

Answer 18

Mesoscale features of glacial erosion are those between 1m and 1 km in size

Question 19

What size feature constitutes a Micro-scale feature

Answer 19

Microscale landforms of glacial erosion are generally less than 1m in size

Question 20

Name 3 macro-scale features

Answer 20

• knock and lochan landscapes
• cirques
• aretes and pyramidal peaks
• glacial troughs
• ribbon lakes
• till plains
• terminal moraines
• sandurs

Question 21

Name 3 meso-scale features

Answer 21

• Criag and tail
• roches moutonnees
• drumlins
• kames
• eskers and kame terraces
• kettle holes

Question 22

Name 3 micro-scale features

Answer 22

• striations
• glacial grooves and chatter marks
• erratics