Geocryology (the study of frozen soils) is a natural and historical science and a branch of geology, concerned with the laws of the formation and the evolution in time and space of frozen ground, its composition, cryogenic structure and properties, and with cryogeological processes and phenomena. The frozen ground may be hundreds of meters thick (up to 1500 m) in the region comprising the freezing zone of the lithosphere characterized by freezing temperatures (to − 15°C) and inclusions of ice or ice crystals.

As any other branch of knowledge, geocryology has resulted from practical needs, and its coming into being has reflected the economic development of huge permafrost tracts, which include currently 25% of all land on our planet and some 50% of the territory of the former USSR.

The subject of geocryology is now well-defined, as are a range of its basic problems, its practical and scientific significance; techniques and procedures for special geocryological researches have evolved; with its major fields and trends established, the prospects of geocryology gaining both in science and in application have proved very promising. Vladimir I. Vernadskiy has noted earlier that it is the limits of cooling below the ground surface which define a task relating to the solution of problems which are all of great scientific and practical importance.

The topic of geocryology is frozen ground, including underground ice and snow accumulations. According to the views of A.B. Dobrovolskiy, V.I. Vernadskiy and P.I. Koloskov, frozen ground occurs in the cryosphere, which is a thermodynamic envelope of the Earth where ice, water and vapour can exist simultaneously under negative temperatures.