August 25, 1959--V. Bronskii (author of the book, Tropoi Kulika) describes the thermokarsts while on one of his expeditions. From page 128:
During our lengthy passages through the swamps, we involuntarily turned our attention to the numerous thermokarstic craters. Why are there so many here? It is well known that thermokarstic craters appear in those sections of permafrost regions made up of clayey (argillaceous) rock with streaks and lenses of ice. It all starts with the destruction of the peat or moss covering which protects the frozen ground from the rays of the sun. As soon as an air hole appears in this protective armor of peat/moss, the deposits saturated with ice begin to thaw and, as a result, a cavity filled with water is formed--a thermokarstic crater. These craters in the form of lakes and swamps sometimes have perfectly round shapes and are widely distributed in this region, but especially often encountered within the Central Hollow. Could not some of these craters have been formed by the falling of meteorite debris after it pierced the thick moss pillow and exposed the ice-saturated deposits? Under this assumption, even a small fragment might provoke the gradual development of a large crater. Kulik [the leader of the first expedition] thought that the majority of these craters appeared when fragments of the meteorite hit the ground, the size of each crater being commensurable with the mass of the fragment which generated it. He was also convinced that the meteorite was ferrous and he conducted searches to prove it. And if the meteorite was stone and fell as a row of fragments? Indeed, each of these fragments might stimulate the development of the thermokarstic process and gradually lead to the formation of a crater, the size of which would depend on the nature of the deposits and the degree of their saturation of ice. However the investigation of thermokarstic formations was beyond our scope. It required specialized and labor-intensive work...
Translated by Phyllis Gagné, University of Georgia Libraries, 1998.