The conditions, processes and landforms associated with cold, non-glacial environments. The term was originally used to describe the climatic and geomorphic conditions of areas peripheral to Pleistoce
ne Ice Sheets and Glaciers. Modern usage refers, however, to a wider range of cold climatic conditions regardless of their proximity to a Glacier, either in space or time. Many, but not all, Periglacial Environments possess Permafrost; all are dominated by Frost Action processes.
Of, or pertaining to, the outer perimeter of a glacier, particularly to the fringe areas surrounding the great continental glaciers of the geologic ice ages. Thus, "periglacial weathering" is said to
have produced certain characteristic land forms.
The climate characteristic of the regions immediately bordering the outer perimeter of an ice cap or continental glacier. The principal climatic feature is the high frequency of very cold and dry wind
s off the ice area. These regions have been thought to create ideal conditions for the maintenance of a belt of intense cyclonic activity.
The environment, which is cold and cryogenic, but not Glaciated, above of the tree line if existent. There is no clear physical limit to the glacial environment and its boundary is diffuse. However, t
he limit to the non-Periglacial Environment is clearly marked by the following indicators: occurrence of Permafrost in depth, including permanently frozen soil and possibly presence of Ground Ice preserved under natural conditions for long periods of time. This constitutes the decisive element whereby an environment is called Periglacial or cryogenic environment dominated by cycles of freezing and thawing affecting rocks and the top of the soil; and presence of Solifluction / Gelifluction and other cryogenic processes (Frost Weathering, sorting, Cryoturbation, etc.) that lead to the so-called Periglacial geomorphology, such as the formation of small scale sorted ground or Rock Glaciers on a mesoscale. For some authors of the northern hemisphere the presence of Permafrost is not a prerequisite for the Periglacial Environment, however, it is for the cryo-scientists working in the Andes.
The Periglacial Environment is defined as those areas in which Frost Action and / or Permafrost related processes dominate. Note: In the early definition of the Periglacial Environment two criteria we
re regarded as diagnostic of the Periglacial Environment: i) there is ground freezing and thawing, and ii) presence of perennially Frozen Ground. Today, Permafrost is considered to not being the only diagnostic criterion because Permafrost is a thermal concept, whereas Periglacial is a geomorphological definition that is concerned with landforms and processes that are not controlled by temperature alone.
Processes associated with Frost Action in cold, non-glacial environments. Periglacial Processes include frost jacking, Frost Sorting, frost wedging, Cryoturbation, and the development of Cryotextures,
Cryostructures and Cryogenic fabrics in soils.