A talik is a layer of year-round unfrozen ground that lies in

permafrost Permafrost () is soil or underwater sediment which continuously remains below for two years or more; the oldest permafrost has been continuously frozen for around 700,000 years. Whilst the shallowest permafrost has a vertical extent of below ...

areas. In regions of continuous permafrost, taliks often occur underneath shallow

thermokarst Thermokarst is a type of terrain characterised by very irregular surfaces of marshy hollows and small hummocks formed when ice-rich permafrost thaws. The land surface type occurs in Arctic areas, and on a smaller scale in mountainous areas such ...

lakes and rivers, where the deep water does not freeze in winter and thus the soil underneath does not freeze either. Sometimes closed, open, and through taliks are distinguished. These terms refer to whether the talik is surrounded by permafrost, open at the top (e.g. a thermokarst lake), or open both at the top and above an unfrozen layer beneath the permafrost.

Supra-permafrost taliks

Due to climate fluctuation or change, some permafrost regions may develop an unfrozen layer between the seasonally thawing and freezing top layer and the permafrost. The layer is called a supra-permafrost ("above the permafrost") talik; it is different from traditional taliks, which are usually associated with water bodies, in that a supra-permafrost talik occurs because the ground that thawed in the summer does not completely refreeze in the winter. Calculations show that climate warming induces supra-permafrost taliks in intermediately cold regions. (In very cold regions, warming simply induces a deeper summer thaw without forming a talik layer whereas in warm, shallow permafrost regions, permafrost quickly disappears.) This type of talik has recently been observed in

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. With time and continued increases in air temperature or snow depth, this talik layer becomes thicker and thicker and the deep permafrost layer eventually disappears. Findings from a scientific study suggest more common occurrence of open taliks within areas of fault zones and areas influenced by large rivers.

References

{{Periglacial environment Physical geography Types of soil Geography of the Arctic Permafrost

Supra-permafrost taliks

See also

References