The word ‘periglacial’ means beyond the ice margin. The term periglacial was introduced by W.V. Lozenski in 1909 to describe the cold-climate processes, landforms and topographic features along the margins of glaciers, past as well as present.

The periglacial regions at present occupy about 20 percent of the earth’s surface. Such regions are located either near the existing permanent ice-sheets or at high altitude in mountainous regions.

The ground in periglacial regions is seasonally snow-free. Under these conditions a typical set of periglacial processes operate including permafrost, frost action and ground ices.

The term periglacial is used to describe the type of climate and climatically controlled landforms adjacent to the Pleistocene ice sheets. However, now this term has been used in extended form to describe non-glacial processes and surface features of cold-climate regions with the least regard for age and their proximity to ice-sheets.

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There are certain geomorphologists who are in favour of restricting the usage of this term (periglacial) to describe only the climate processes and topographical features formed by freeze-thaw activity in a zone lying adjacent to ice sheets. These geomorphologists do not consider it necessary for such regions to coincide with the permafrost.

In view of L. Peltier, a periglacial morpho-genetic region must have an annual average temperature ranging from -15° C to -1°C, and an average annual rainfall (excluding snow) ranging between 127 mm and 1397 mm.

Besides frost action, the other characteristic features of a periglacial region are seasonally snow-free ground. Remember that these periglacial regions are dominated by processes that relate to physical weathering and mass movement, soil and climate.

As Sparks and West put it, “Ideally, it (the periglacial region) is a zone of permanently- [preferred usage is ‘perennially’ frozen subsoil (permafrost), seasonally-thawed topsoil (active layer), frequent changes of temperature across the freezing point, and an incomplete vegetation cover of herbaceous plants and dwarf species of trees, for example, dwarf birch and willow”.

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However, presently the modern periglacial zone is regarded as coincident with the region of permafrost (frozen ground).