permafrost

Question 1

permafrost

Answer 1

• Ground that remains at or below 0 degrees (frozen) for at least 2 years
• Cryptic ground (below zero often, not always containing ice)
• three types: continuous, discontinuous and sporadic

Question 2

continuous permafrost

Answer 2

• Occurs within the artic circle
• Annually never above -5 degrees
• Permafrost may thaw below lakes insulating the ground

Question 3

discontinuous permafrost

Answer 3

• Occurs in islands separated by warmer areas which receive insulation from lakes, rivers, vegetation or man-made structures
• Further south than continuous permafrost

Question 4

Sporadic permafrost

Answer 4

• Further south than discontinuous permafrost

- Annual temperatures are only just below freezing point and frozen ground occurs in isolated patches

Question 5

Talik

Answer 5

• Unfrozen areas, soil and rock

Question 6

Active layer

Answer 6

• Summer temperatures melt surface layer of permafrost
• This layer can be very mobile
• Varies in thickness depending on latitude and vegetation cover
• Layer above permafrost
• Important for landforms created in periglacial landforms
• key processes: hydrological - reduced friction forming solifluction lobes and
  biogeochemical - chemical weathering, plant acids breaking up the ground

Question 7

changes in northern Canada to permafrost

Answer 7

Resolute: depth 400m, temp -12
Yellowknife: depth 50m, temp -5.5
Hay River: depth 10m, temp -1