Glacial Environments

Question 1

What are glaciers?

Answer 1

• One of the most important agents shaping landscapes we inhabit
• A key indicator of recent and ongoing climate change
• Direct cause of potential future environmental catastrophe
• Main water source for many of worlds major rivers

Question 2

How are glaciers formed?

Answer 2

Glaciers begin to form when snow remains in the same area year-round, where enough snow accumulates to transform into ice. Each year, new layers of snow bury and compress the previous layers

Question 3

What is basal motion?

Answer 3

Basal motion erodes, entrains, transports and emplaces sediment and in process creates sediments and landforms

Question 4

What is a glacier thermal regime?

Answer 4

The thermal regime of a glacier is a function of ice temperature (which again is a function of air and ground temperatures, with some glaciers being heated from below by geothermal heating) and the pressure of the ice

Question 5

What are the tree types of thermal regime?

Answer 5

1) Temp - warm ice except seasonality warmed and cooled surface layer
2) Cold - entirely cold ice
3) Polythermal - both warm and cold ice

Question 6

Why is the temperature of the glacier bed critical?

Answer 6

• Glacier bed is warmed by friction of movement and geothermal heat
• It controls whether there is water at the glacier bed, which determines whether it moves through basal motion

Question 7

Outline glacial landscapes

Answer 7

• Glaciers are orderly systems

- The landscapes they generate are closely associated with their climate, thermal regime and flow dynamics

Question 8

What are the different types of glacial landforms?

Answer 8

• In a ‘typical’ mid-latitude temperate glacier, clear relationships in the development:
  1) erosional landforms
  2) subglacial bedforms
  3) ice-marginal landforms
  4) meltwater landforms

Question 9

What are sub glacial bedforms?

Answer 9

• Continuum of streamlined features (both erosional and depositional) formed at the bed of a glacier moving through basal motion
• Highly controversial features with alternative process-form models:
• Highly elongate bedforms (MSGLs) suggested to reflect unstable, fast ice in ice-streams and surging glaciers

Question 10

What are ice-marginal landforms?

Answer 10

• Glacier margins are complex in detail, but broadly comprise formation of moraines and moraine systems:
• Moraine ridges: terminal, lateral, medial
• Ice-marginal aprons:
• Suite of landforms that mark the lateral edge/margin of a glacier

Question 11

What are proglacial landforms?

Answer 11

• Means by which glaciers extend their influence well-beyond the glacial margin
• Extreme annual and diurnal variation in melter release
• Very high sediment load
• Risk of catastrophic floods – Jokullhlaups