Periglacial Processes + Landforms

Question 1

What do periglacial areas contain?

Answer 1

Permafrost- permanently frozen ground with a top layer that can melt in summer (ACTIVE LAYER)

Question 2

What is continuous permafrost?

Answer 2

All the ground is frozen

Question 3

What is discontinuous permafrost?

Answer 3

Only patches of the ground are frozen

Question 4

What’s sporadic permafrost?

Answer 4

The annual temp is around freezing point and permafrost only occurs in isolated spots

Question 5

What does the temperature have to be like for discontinuous permafrost to form?

Answer 5

Below 0° for at least two years

Question 6

What does the temperature have to be like for continuous permafrost to form?

Answer 6

Mean annual temp must be below -5°

Question 7

What is solifluction?

Answer 7

As the layer of permafrost is impermeable if the temp gets above 0° in summer the active layer melts but the water can’t go anywhere
-meaning the active layer gets waterlogged and will easily flow -SOLIFLUCTION

Question 8

How do ice wedges form?

Answer 8

When the temperature drops low in the wings the group contracts and cracks from in the permafrost

• in the warmer month the increase in temp cause the active layer to thaw and meltwater to seep into cracks
• the permafrost layer is still frozen so water will freeze in the cracks

Question 9

What is frost heave?

Answer 9

When water in the ground makes humps on the surface

Question 10

How is frost heave formed?

Answer 10

When the active layer freezes the ice forms a lens shape

• in the fine grained soil the ice lifts up the surface layers of the soil
• ice lenses also form underneath stones due to them kissing heat quacking and faster than the surrounding soil

Question 11

What happens as the ice lens expands in frost heave?

Answer 11

They push stones upwards toward the surface of the ground and eventually the stones rise above the surface of the ground

Question 12

What is patterned ground?

Answer 12

When stones get pushed to the surface by frost heave,once they reach the surface they roll down to the edges of the mounds that have formed

Question 13

What is nivation?

Answer 13

When the snow gets into a hollow in the ground and increases the size of the hollow

• as the temp is periglacial freezing and thawing happens
• every time the ice freezes it expands,leading to frost shattering eventually breaking off parts of the rock at the base

Question 14

What happens to material in nivation?

Answer 14

Material gets carried away by meltwater and eventually the hollow becomes deeper and wider
-this is the beginning of a corrie

Question 15

What are pingos?

Answer 15

Ice filled periglacial hills

-they are conical hills with a core of ice that can be as large as 80m high and 500m wide

Question 16

What are then two types of pingos?

Answer 16

Open & closed systems

Question 17

What are open system pingos?

Answer 17

These form where there discontinuous permafrost

• the groundwater is forced up through the gaps between the areas of permafrost
• water collects together and freezes forming a core of ice that pushes the ground upwards

Question 18

What are closed systems pingos?

Answer 18

Form in areas of continuous permafrost where there’s a lake at the surface

• the lake insulates the ground so the area beneath remains frozen
• When the lake fries up and the ground is no longer insulated,permafrost advance the area of the area of unfrozen ground

Question 19

What happens to the water that collects in the unfrozen ground of a closed pingo?

Answer 19

The water freezes to create the core of ice that pushes the ground up