抄録
Eastern Siberia maintains an unique position in Boreal Forest as deciduous coniferous forest. It adapts to the dry and cold winter climate, and Larix spruce represents its characteritics so well. Here, also, there is no evidence of continental glaciers in the past, but permanent tundra exists in place of glaciers. Its main part seems to us as the product of diluvial deposits. From many points of view, the condition of formation is contradictory between glacier and tundra. If the glacial period of diluvium corresponds with the growth period of tundra, both would have maintained their influential spheres separately, without changing their mutual geographical orientation. If each formation periods differ, permanent tundra would due much to the second inter glacier period. In either case, Eastern Siberia experienced no great change since diluvium, but most flourishing period of tundra formation would be coinside with spreading period of loess accumulation and inland basin in southern part of continent.
