Glacial Landscapes - Introduction to Periglacial Landscapes

A periglacial environment used to refer to places which were near to or at the edge of ice sheets and glaciers. However, this has now been changed and refers to areas with permafrost that also experience a seasonal change in temperature, occasionally rising above 0 degrees Celsius. But they are characterised by permanently low temperatures.

Location of periglacial areas

Due to periglacial environments now referring to places with permafrost as well as edges of glaciers, this can account for one third of the Earth’s surface. Far northern and southern hemisphere regions are classed as containing periglacial areas, particularly in the countries of Canada, USA (Alaska) and Russia.

Permafrost is where the soil, rock and moisture content below the surface remains permanently frozen throughout the entire year. It can be subdivided into the following:

• continuous (unbroken stretches of permafrost)
• extensive discontinuous (predominantly permafrost with localised melts)
• sporadic discontinuous (largely thawed ground with permafrost zones)
• isolated (discrete pockets of permafrost)
• subsea (permafrost occupying sea bed)

Whilst permafrost is not needed in the development of all periglacial landforms, most periglacial regions have permafrost beneath them and it can influence the processes that create the landforms. Many locations within extensive discontinuous and sporadic discontinuous permafrost will thaw in the summer months. The surface layer that seasonally thaws is known as the active layer.