2A.3 Periglacial processes produce distinctive landscapes

Question 1

Distribution of past and present periglacial landscapes can be explained through - what and how many?

Answer 1

Permafrost - 3 types. Including - Sporadic, continuous and discontinuous.

Question 2

What are periglacial environments?

Answer 2

Refers to the climate conditions and margins that are characterised by the margins of glacier ice during the Pleistocene.
Can be defined with the following characteristics:
- intense frosts during the winter and snow-free ground during summer.

Question 3

Continuous permafrost -

Answer 3

• Forms in the coldest areas in the world with mean annual air temperatures below -6 degrees can be frozen to the depths of hundreds of metres.

Question 4

Discontinuous permafrost -

Answer 4

More fragmented and thinner temperatures usually between -1.5 and -5 degrees, can be much shallower up to 35m in depth.

Question 5

Sporadic permafrost -

Answer 5

Occurs at the margins of periglacial environments, covers the smallest areas with mean air temperatures between -1.5 and 0 degrees.

Question 6

Active layer -

Answer 6

The top layer of soil in permafrost environments that thaws during the summer and freezes during the winter.

Question 7

What does thaw mean?

Answer 7

Become a liquid as a result of warming up.

Question 8

A periglacial definition

Answer 8

‘An area where soil and rock has not risen above 0°C for at least 2 consecutive years’

Question 9

Talik -

Answer 9

Areas of unfrozen ground

Question 10

Periglacial processes - Freezing and thawing - Nivation

Answer 10

Collection of seasonal snow in hollows encourage frost weathering beneath them, occurs underneath snow. Repeated cycles of melting, freezing and transportation form nivation hollows.

Question 11

Periglacial processes - Freezing and thawing - Frost heave

Answer 11

When soil particles or small stones are forced to the surface. Helped by capillary action of water in the soil. The freezing occurs from the surface downwards which helps ice crystals to form within soil pores. As the ice expands it forces stones and ice crystals to the surface.

Question 12

Periglacial processes - Freezing and thawing - Freeze thaw -

Answer 12

Type of weathering alternate of freezing and thawing in cracks and rocks causing them to spilt expanding them by 9%.

Question 13

What is solifluction?

Answer 13

A form of mass movement, downward slope of saturated soil, on slopes. When one area of soil flows faster than other areas, the active layer of permafrost moves easily over solid ground beneath

Question 14

Meltwater and wind erosion

Answer 14

Periglacial regions often have strong winds and these continue to erode rock debris produced by glaciers and ice caps.

Question 15

Periglacial environments may include

Answer 15

Northern Russia or Northern Canada

Question 16

Ice wedge polygons -

Answer 16

• Usually around 20-30m in length
• Formed from continuous permafrost
• Ground freezes in the winter and thaws in the summer. (continued freezing and thawing cycles)
• During the winter, water freezes so it expands, pushing the ground apart.
• Maintained as water further pushed down from the surface keeping the polygon shape.

Question 17

Patterned ground -

Answer 17

Stone circles are smaller in size and are usually less than 10m across and are a result of frost heave (pushes larger stones to the surface) Formed by a series of movements resulting from frost action and frost push.
FP - causes the stones to move upwards whereas FH causes the stones to migrate outwards to form circles providing the basis of the pattern.
The up doming created by the heave is achieved from larger stones rolling down due to gravity while finer sediments remain central
Found Svalbard Norway.

Question 18

Pingos -

Answer 18

Ice core mounds 30 - 70m in height and 100 to 500m in diameter mounds are either conical or elongated. Two types closed or open.

Question 19

Closed pingos -

Answer 19

Found in Greenland of continuous permafrost, form from the downwards movement of permafrost and accumulates at death. Causing the ground surface to dome. Usually a small lake is located below allowing the permafrost to advance it is put under hydrostatic pressure and freezes to push the water upwards (the unfrozen ground is known as a talik)

Question 20

Open pingos

Answer 20

Found in Canadian Arctic and Siberia, formed in areas of discontinuous permafrost, freely available groundwater is drawn towards the expanding ice core so it grows from below the ground. Moves from small areas of a talik because of the active layer re-freezing in winter, as it freezes near the surface it causes the ground surface to dome upwards.