Introduction

Summary

Geocryology as part of planetary cryology

Geocryology is a branch of a more general science - cryology of the planets. Frozen ground as a natural-historical geological formation is not unique to and typical of the Earth only. It is widely developed on other planets of the Solar system such as Mars and Pluto as well as on the satellites of Jupiter, Saturn, Uranus, Neptune and Pluto. This becomes clear and evident if we take into account the fact that the void of the Universe with its temperature being close to absolute zero is ‘a kingdom of cold’. Planets and their satellites, asteroids and other solid bodies within this space, must naturally be in thermodynamic equilibrium with the space environment. Consequently the temperature of at least the near-surface rock units on the overwhelming majority of planets far removed from the Sun must be below 0°C. There is always a chemical compound (matter) dominant in the atmosphere of a planet, which exists simultaneously in three states: solid, liquid and gaseous under a given temperature, depending on the temperature of each planet. The solid phases of this matter (ice) on the planet can form either separate large ‘ice’ aggregates and monomineral rocks or enter into the composition of frozen rocks in the form of the particular mineral component. Solid celestial bodies of the Universe must be cryogenic (Table 1) in the overwhelming majority of cases, i.e. be characterized by development and existence of frozen rocks.