periglacial processes and landforms

Question 1

what are the periglacial landforms?

Answer 1

ice wedges
patterned ground
pingos
loess

Question 2

formation of ice wedges?

Answer 2

Formed by the refreezing of the active layer during winter causing soil to contract and cracks open. During the melting of the summer the cracks fill up with meltwater and sediment then refreeze the following winter which will widen and deepen the crack

Question 3

formation of patterned ground?

Answer 3

Caused by frost push where large stones become chilled more rapidly than the soil. Water below such stones freezes and expands which push propels the stones upwards, whilst frost heave causes stones to migrate outwards to form circles

Question 4

formation of open system pingos?

Answer 4

: Occur in valley bottoms and in areas of thin or discontinuous permafrost. Common in East Greenland. When the surface layer freezes, water is trapped in the talik (unfrozen layer). This water comes under pressure and may move towards the surface where, surrounded by permafrost, it freezes into an ice core. This causes the surface to dome upwards. As water under pressure finds its way to the surface, the ice dome and thus the pingo, continues to grow

Question 5

formation of closed system pingos?

Answer 5

(Mackenzie River Delta in Northern Canada) are generally found in lowland areas where permafrost is more continuous. They often form on the sites of small lakes. As these lakes fill with sediments from meltwater, the surrounding permafrost advances and squeezes the unfrozen sediments below the lake. When the lake itself is frozen, the water in the underlying sediments causes the surface to dome upwards creating the pingo.
If the dome cracks, the ice core may melt leading to a collapse of the pingo and a pond forming in the central crater.

Question 6

formation loess?

Answer 6

fined grained material transported and deposited by the wind. The sediments come from glacial outwash plains, where glaciers deposit fine particles of silt and clay, or from desert areas that have little vegetation to anchor small particles. Prevailing wind patterns blowing across these environments can produce thick deposits of loess downwind of the area. Examine the images to interpret how loess is formed.

Question 7

what are the periglacial processes which produce distinctive landscape?

Answer 7

freeze thaw, frost have, nivation, solifluction

Question 8

process of freeze thaw?

Answer 8

weathering-water expands 9% upon freezing-shatters glass

Question 9

process of frost have?

Answer 9

The upward movement of soil and rocks by the freezing and expansion of soil water. Frost push: occurs when cold penetrates the ground. Large stones become chilled more rapidly than the soil. Water below such stones freezes and expands, pushing up the stones. Frost pull: can alter the orientation of a large stone causing it to stand upright. This occurs when ice creeps downwards from the surface. The growth of ice crystals on the upper part and the drying of the soil around the lower part cause the stone to be pulled into a more vertical inclination Migration of sub surface water to the ‘freezing front’ helps create pingos

Question 10

process of solifluction?

Answer 10

mass movement of soil affected by alternate freezing and thawing
soil saturated with meltwater down hill of permafrost in a tundra region