When thawing the thicknesses of permafrost, as well as soil ice, elevated dry areas are often omitted, the resulting cavities are filled with water and form lakes and wet lowlands. The very relief of the terrain in the field of permafrost is changeable, since the melting of centuries -old stocks of ice lowers large areas or, on the contrary, with the formation of soil ice and tubercles, sometimes bloating of the upper layers to a height of several tens of meters.
