CONCEPT OF SUBRELIEF (RELIEF OF UNDERGROUND CA VITIES)
Investigation of «relief» of the underground cavities doesn‘t actually match in modern geographic science with a paradigm of studying relief as an object of geomorphology. The article suggests a sci entific conception of studying underground cavities in geomorphology (and geography). The term of «subrelief » (literally «under the relief» and «almost relief») is introduced to define solid surfaces of undergr ound cavities proceeding from the meaning of «relief» as a complex of irregularities on the solid Earth‘s surface which is accepted in the Russian geomorphologic science. The article also introduces specific terms, genetic classification of subrelief form and zoning of underground cavities by depth, and defines the limits of subrelief concept application. Some specific features of subrelief, such as closed volume, isolation from the Earth‘s surface processes, deep zonation etc., are also reviewed in the article. Underground cavitie s are the habitat of relict and unique plants and animals. Many hazardous and dangerous processes in urban are as are closely related to the subrelief.