BEDROCK LITHOLOGY AND NATURAL COMPLEXES OF RIVER VALLEYS (A CASE STUDY OF THE NORTH-EAST OF RUSSIA)
Bedrocks are subdivided into three types (blocky, rubbly and poorly lithified rocks) differing by interaction of fragments prevailing at the initial stages of weathering with streams. The expediency of this typification is substantiated along with the dif ferentiation of territories based on dominance of one of the three types. As an example, an overview is used of the results obtained in the course of the author’s research in Northeastern Russia. It is shown that the dominance of rocks of the rubbly type in this case determines the prevalence of braided rivers and their specific hydrological regime gives rise to alluvium of numerous pref erential flow pathways. Evidences is provided for the concentration of underground flows in these pathways which shows itself in a number of non-trivial features of groundwater regime (temperature and level variations) and ensures a very high effective permeability of alluvium. It is proved that these features lead to an intense water and heat exchange between rivers and their floodplains and to formation of extensive taliks on which the unique phytocenoses of long-boled mixed forests develop. It is demonstrated that an abundance of open taliks ensures a tight linkage of surface and subsurface waters and a large storage of them. One of the consequences is that in Northeastern Russia the seasonal glaciation (the proportion of meltwater from aufeis in the overall surface runoff) is much larger than in all the other territories. The approach considered here holds promise for a number of geographical disciplines enhancing objectivization of the regionalization of study territories.