Glaciation - Unit 7

Question 1

What are the 3 time scales that glacial landforms change over?

Answer 1

• Rapid
• Seasonal
• Long term

Question 2

Give an example of rapid change

Answer 2

Rockfall which creates scree slopes

Question 3

Name a case study of a glacial landform that has experienced rapid change?

Answer 3

• Randa rockslide, Switzerland (1991)

Question 4

Name 3 key facts about the Randa rockslide case study

Answer 4

1- Around 15 million m³ of rock slid down to the valley
2- Caused by intense FTW
3- Total of 33 million m³ of rock fell 600m to the valley floor - changing the profile dramatically

Question 5

How and why do fluvioglacial streams vary both daily and seasonally?

Answer 5

Daily - temp changes daily, affecting discharge

Seasonally - meltwater may not be present in winter as the temperature may never rise above PMP

Question 6

Give an example of seasonal change

Answer 6

Infilling of lakes, e.g. kettle hole lakes and proglacial lakes with varves

Question 7

What are alluvial fans?

Answer 7

Deposits of stream load at the base of a steep slope

Question 8

How do alluvial fans form?

Answer 8

• Energy is gained as streams flow down mountains with a steep gradient = can carry large amount of sediment
• Velocity is reduced when the stream emerges at lower altitudes to flatter grounds
• Sediment is deposited
• As stream fans out, creates triangle-shaped feature
• Narrow point = apex
• Wide triangle = apron

Question 9

How are ribbon lakes formed?

Answer 9

• Similar to formation of alluvial fans
• As the stream enters the lake, its velocity drops, resulting in the stream load being deposited
• Over thousands of years, this process can completely infill lakes

Question 10

How are misfit streams formed?

Answer 10

The running water that drains the post-glacial lanscape will converge at the base of a glacial trough