Permafrost

found on ground rich in coarse-grained material which is located close to the surface.
Solifluction is regarded as one of the most widespread processes of soil movement in
periglacial areas. The following conditions favour the development of solifluction: a slope angle
of 8-12°, (although it is often observed within a much wider range of 2-25°); the presence of
tine-grained soils, deposits, and ground, transformed by cryogenic weathering; and availability
of water-saturated thawing soils. The major influence upon solifluction is vegetation.
Solifluction in mountains is characteristic of the lowest belt of the Arctic and subarctic
mountains. The typical solifluction regions are the Chukchi and Taymyr peninsulas where
alternating stripes of fine-grained and coarse stony deposits (sorted solifluction) are found.
Another type is the block field or block streams (also termed kurum), formed by frost
weathering of exposed rocks. Solifluction terraces with treads reaching 5 m in width and 1.5 m
in depth, tongue-shaped lobes and ramparts about 0.5 m high are a distinct feature of the
landscape. On the steeper (15-25°) slopes, these forms have larger dimensions: terraces have a
width of 50-100 m and a height of 1.5-3 m and the ramparts are about 3 m high.
Key words: cryolithozone, thickness of permafrost, cryogenic processes, ice wedges,
thermokarst, patterned ground, solifluction.
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