Permafrost
Permafrost, or “ice sphynx” is one of the most interesting facts about Yakutia nature.
Almost all vast territory of the Rebublic is taken up by continous permafrost. And, virtually all of it is solid with the exception of local areas of talik, permafrost free land under major riverbeds and big lake basins. But not only the permafrost spread area is impressive, but also the thickness of the active layer. It is said the world recorded permafrost thickness of 1 500 m can be found in Anabar area, upper reachers of the Daldyn River, and permafrost temperature of -13,9є C in the town of Yakutsk. Indeed Yakutia is an ice sphynx, an area of great permafrost.
Permafrost, or permanently frozen ground, is soil, sediment, or rock that remains at or below 0°C for continous period of time. It’s typical of frozen rock to have high ice content. There are basically two types of subterranean ice.
The first one occurs in soil in form of lenses, interlayers and wedge-like streaks and under the influence of very cold temperatures it expands creating so called frost-sheterred cracks. The process is usually accompanied by droning, and then black yawning twisting or broken strip (several cm wide and 2-3 m deep) spreads on the ground. Every year more water gets into cracks, thus increasing and expanding them.
The other kind of ice occurs in rocks due to void water freeze-up. Such subterranean ice makes rock particles solid and watertight due to bonding.
Continious permafrost topsoil, or active layer, thaws up only 0,2 m deep in the North and 2,5 m deep in the South during short summer period. Closing in to permafrost in winter time this thin soil layer indeed becomes active environment for many dynamic and empetuous vital processes. It is amazing how inspite of cold climate and thick permafrost, you can find forests, weat fileds, fresh potatoes, vegetables and even watermelons and melons in Yakutia.
According to current findings continous permafrost in the Norhthern parts of Yakutia had formed in Quaternary period, pleistocene age about 2 mln years ago. At that time most complex climate changes took place: rapid fall of temperature lead to average air temperature drop to -30, -35 є C in the coldest months. In most effected by cooling Northern territories surface glaciers developed in some areas.
At the time of cold age cloudless anticyclon with frosty little snow winters had set in over vast ice-covered territories. After period of surface intensive cooling, the cold then penetrated further down exposing the soil to frost and transforming it. As a result of cooling over period of several thousand years, the permafrost penetrated dozen and hundred meters down leaving out only big riverbeds and lake basins. It is considered that frozen rock appeared exactly at the time of severe pleistocene age climates.
Subsequently continous permafrost shifted to the South and involved all Yakutia territorry. According to geological information, the age of frozen rocks is 1 mln years in Central Yakutia and 500 years in Southern Yakutia.
(Courtesy of Bichik Publishing. Yakutia Amazing and Mysterious).
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