Submarine valleys can be subdivided into several types which differ considerably in genesis and morphology; besides submerged fluvial and glacial valleys (inherited relict features), several types of submarine valleys seem to be accounted for by turbidity currents, i. e. submarine canyons, submarine gullies, abyssal valleys of continental rise and ocean floor. Rift valleys are formed by tectonics only; tectonic fractures contribute consign derably into formation of submarine canyons and transversal gorges crossing mid-oceanic ridges. Bottom abyssal currents are not sufficiently studied, but it is beyond any doubt that they participate in the formation of submarine valleys in deep ocean zones, in particular in inter-depression passes. It seems that valleys due to turbidity currents were greatly influenced by Pleistocene glaciations. Ice edge was often situated close to shelf edge and debris melted from the ice created large turbidity currents which eroded not only continental slope but abyssal zones as well.