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Permafrost temperature profile. Permafrost occupies the middle zone, with the active layer above it, while geothermal activity keeps the lowest layer above freezing. The vertical 0 °C or 32 °F line denotes the average annual temperature that is crucial for the upper and lower limit of the permafrost zone, while the red lines represent seasonal temperature changes and seasonal temperature ...
The distinction between pereletok and permafrost does not seem to be universally defined [4] and practically speaking, distinguishing the two in the field is difficult. [5] Sometimes three distinct types of frozen ground are identified based on how long they remain frozen: 1) permafrost (permanently frozen), 2) pereletok (frozen for multiple ...
Permafrost, which is soil (or rock) that remains below 0 °C for at least two consecutive years, [14] forms a solid matrix in soil which can extend to a depth of hundreds of meters. [15] The permafrost prevents trees from developing deep root systems; for example, the black spruce that has adapted to permafrost soils has no significant taproot ...
The permafrost may begin from the surface of the ground or many meters beneath it, and may extend from just a meter to over a thousand meters in thickness. Permafrost contains a significant portion of the Earth's water and carbon, and prevents surface water from penetrating very deep into the ground, making it responsible in part for the ...
Alternatively, in Arctic and Antarctic locations the freezing depth is so deep that it becomes year-round permafrost, and the term "thaw depth" is used instead. Finally, in tropical regions, frost line may refer to the vertical geographic elevation below which frost does not occur. [2]
In ecology, roots of plants cannot penetrate beyond the active layer, which places restrictions on which plants can grow in permafrost. In construction, the thaw depth is a major factor in ensuring the structural integrity of the objects in question.
A talik is a layer of year-round unfrozen ground that lies in permafrost areas. In regions of continuous permafrost, taliks often occur underneath shallow thermokarst 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.
Periglaciation (adjective: "periglacial", referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedges and other structures.