periglacial processes

Question 1

What is a periglacial environment?

Answer 1

exist at the edges of glacial / polar environments and cover 20% of earth’s land surface

Question 2

what are the three characteristics of periglacial environments?

Answer 2

1) Found on the edges of glacial / polar environments - alaska / russia / Northern Europe
2) No permanent covering of ice - do experience cold for most of year (frost) with periodic snow
3) Permafrost is one key feature of periglacial environments

Question 3

Whats the permafrost?

Answer 3

Where a layer of sediment, soil or rock below the ground remains frozen for 1 year+

Question 4

Whats the active layer?

Answer 4

The layer above the permafrost that thaws in summer and refreezes again in winter.

Question 5

What is a talik?

Answer 5

A layer of unfrozen ground that is surrounded by permafrost due to anomaly in thermal conditions.

Question 6

What is continuous permafrost?

Answer 6

A continuous sheet of frozen material which extends without any breaks→ found in Siberia Russia - higher latitudes

Question 7

What is discontinuous permafrost?

Answer 7

Is permafrost that is broken up into separate areas → Hudson bay Canada - warmer regions

Question 8

What is sporadic permafrost?

Answer 8

• Found when mean annual temperature is just below 0

the summer temperatures reach several degrees above

isolated pockets of permanently frozen ground remain below the surface.
Lower latitudes - prevent complete thawing

Question 9

What is frost action ?

Answer 9

• Leads to the accumulation of angular rocks at the foot of a mountain slopes or a boulder strewn landscapes
• Cracks in the ground formed by winter contraction become filled with water during the day
• Water freezes and expands - enlarges the crack
• Over many years an ice wedge is formed up to 3m x 10m

Question 10

What is a soliflucation?

Answer 10

• The water in the upper active layer melts leading to soil becoming saturated
• If on a slope causes the downhill movement of top layer of soil under force of gravityAKA Gelifluction

Question 11

rockfalls

Answer 11

• Result from freeze thaw action
• Scree slopes are a common feature of periglacial environments
• On flat land extensive areas of angular boulders can be left known as block fields

Question 12

Nivation

Answer 12

Snow collects in hollows especially on north facing slopes

With increase amount of weight if the ice begins to disintegrate the underlying rock

Question 13

Frost Heave

Answer 13

A subsurface process that leads to vertical sorting of material in the active layer.

• Stones within finer material heat up and cool down faster than their surroundings as have lower heat capacity
• Temperatures fall water beneath the stones freeze and expand pushing the stones upwards to the surface
• Ground ice also pushes up finer material
• Warm season → thawing causes ice to convert back to water and the contracting surface drops particles in elevation → this is influenced by gravity causing for particles to move downslope