Summary

Periglaciation is a set of processes that happen in areas near to ice sheets

A key characteristic of periglacial areas is permafrost or permanently frozen ground

In summer, the ground may become unfrozen for a short while. This unfrozen surface layer is known as the active layer

An important process in periglacial areas is frost heave. This results from ice crystals or ice lenses forming in fine-grained soils. This leads to the formation of patterned ground

A second type of patterned ground forms due to ice wedges. These are created when the ground freezes and cracks

The most dramatic landform is the pingo. These are dome-shaped hills which may rise to around 50 m above the generally flat tundra landscape. Some of the pingos have depressions in their surfaces and some have ice cores at their centre

Mass movement processes are very active in periglacial areas. On a small scale, soil creep moves material down steep slopes.

On a larger scale, solifluction moves material on more gentle slopes