Takyr

(Turkic, “smooth,” “even,” “bare”). (1) The bottom of a lake that dries up periodically; found in areas of clayey soils in desert and semidesert zones. During the wet season, the takyr is covered with a thin layer of water that, upon drying up, exposes the sticky, viscous mud. The mud shrinks as it dries, becoming covered with a crust that is broken up by cracks into variously shaped polygons ranging in size from several square meters to dozens of square kilometers, depending on the composition and degree of salinity of the sediment. A takyr is formed where the water table lies more than 1.5 m below the surface, when excess salts seep into the groundwater and return to the surface through capillaries.

(2) A type of soil that forms in flat, clayey depressions in deserts and semideserts. There are two sharply divided levels in the soil: the upper layer, which is up to 8–10 cm thick and consists of a thick, stratified clay crust that contains no salts, and the underlying layer, which consists of slightly altered saline soil-forming rock. The takyr is almost entirely devoid of vegetation; the flora consists exclusively of algae and lichens.