Pingos (periglacial)

Question 1

Open system:
Stage 1

Answer 1

• water from surrounding slopes collects in valley-bottom under gravity within an area of talik

Question 2

Open system:
Stage 2

Answer 2

• freezes & expands under artesian pressure
• overlying surface material forced to dome upwards
• common in E Greenland

Question 3

Closed-system
Stage 1

Answer 3

• lake water seeps into talik below
• temp falls = talik gradually surrounded by advancing permafrost (trapped by the permafrost below and frozen lake above)

Question 4

Closed-system
Stage 2

Answer 4

• saturated talik/ unfrozen ground compressed by the expanding ice around it & is under hydrostatic pressure
• talik itself eventually freezes & pushes up overlying sediments
• over 1400 in Mackenzie delta of Canada