Ground ice features

Question 1

A variety of ground ice features form as a result of what?

Answer 1

A variety of ground ice features result from repeated cycles of freezing and thawing in the active layer.

Question 2

What happens to the active layer during the summer?

Answer 2

During the summer, when the energy balance is positive (because the daily input of solar energy exceeds the output of terrestrial long-wave radiation), the active layer deepens.

Question 3

Why does the active layer often become waterlogged in the summer?

Answer 3

Often the active layer becomes waterlogged, this is because its lower limit is the impermeable permafrost table, resulting in poor drainage.

Question 4

What happens to energy balance in autumn?

Answer 4

In autumn, as the energy balance becomes increasingly negative, ground water freezes again.

Question 5

The amount of ice that forms depends upon what?

Answer 5

• The amount of water present
• The texture of active layer materials (fine-grained clays retain water well, but temperatures need to drop below 0 degrees before extensive freezing takes place; coarse sands are poor water retainers, but freezing does occur at 0 degrees)

Question 6

Describe the distribution of ice formation in the active layer?

Answer 6

Ice formation in the active layer is unevenly distributed.

Question 7

Give some examples of ground ice features?

Answer 7

• Ice-wedge polygons
• Patterned ground
• Pingos

Question 8

Which process has a fundamental role in the formation of ground ice features in periglacial environments?

Answer 8

Repeated cycles of freezing and thawing in the active layer.