A term describing cold-climate processes and landforms, an environment with severe frost in non-glacial conditions and have much ground ice, mass movements, and strong winds. It applies to the region surrounding a glacial area and regions immediately beyond the ice-front during a glaciation. In a periglacial zone, part of the ground is perennially frozen. This so-called permafrost layer is covered by a layer which thaws and freezes seasonally, the active layer. Such seasonal changes give rise to several processes, some of which sort the constituents of the active layer and are collectively known as cryoturbation. A variety of landforms, including involutions, ice wedges, and pingos, are formed in the active layer and permafrost. Hillslopes become mantled with frost-shattered rubble that move downslope during cycles of freezing and thawing. Rivers are usually seasonal in the periglacial zone, and erosion by frost action is dominant. Wind erosion and deposition is often an important factor, and caused the formation of the huge deposits of loess and cover-sands in Europe and Asia. The periglacial zone is of interest because it would have been the environment in which man lived for long periods of time during the Devensian/Weichselian cold stage. During the coldest periods of the Quaternary (the last 1,600,000 years), the periglacial zone was enlarged to approximately twice its present size.