Periglaciation

Question 1

Permafrost

Answer 1

• Permanently frozen ground
• Occurs where soil temps remain below 0 degrees
• 2 consecutive years

Question 2

Continuous permafrost

Answer 2

• Found mainly within the Arctic Circle

- The mean annual temperature is -5 degrees

Question 3

Discontinuous permafrost

Answer 3

• Lies further south in the northern hemisphere
• Mean annual temp is between 1 and 5 degrees
• Consists of islands of permanently frozen ground
• Separated by less cold areas which lie near to rivers, lakes and sea.

Question 4

Sporadic permafrost

Answer 4

• Found where the mean annual temperatures are just below freezing
• Summers are several degrees above 0 degrees

Question 5

Types of permafrost

Answer 5

1. Continuous
2. Discontinuous
3. Sporadic

Question 6

Active layer

Answer 6

• Areas where summer temps rise above the freezing point
• Surface layer thaws = active layer
• Under some local conditions can become very mobile for a few months before freezing again - vary in depth from a few cm to 5m.
• Often saturated as meltwater can’t infiltrate downwards through impermeable permafrost.
• Meltwater is unlikely to evaporate in the low summer temps or drain downhill since most slopes are very gentle.
  = pockets of ground are unfrozen at low lats
• Active layer = waterlogged + heavy = flow
  Flow = solifluction + occurs in gradient
  = Solifluction lobes

Question 7

Talik

Answer 7

Unfrozen layer beneath or any unfrozen material within the permafrost.

Question 8

What is the lower limit of the permafrost determined by?

Answer 8

Geothermal heat which causes temps to rise above 0 degrees

Question 9

Frost creep

Answer 9

• Mass movement on slopes during freeze-thaw
• Water in soil expands when frozen
• Soil particles = forced upwards at right angle to slope
• Ground thaws = soil particles move vertically down