The Eastern Siberian system* of Cenozoic rift faults and depressions, extending for nearly 1 800 km, is associated with a large domal uplift which frames the craton area of the Siberian platform in the south and southeast. The central segment of this system, in which the largest and oldest depression of Lake Baikal is located, runs immediately along the margin of the Siberian craton in the zone where it links with the Sayan-Baikal mobile belt. This depression makes up 1/3 of the total rift zone. The Baikal rift has been expanding from the central segment towards the northeast and west. A maximum thickness of sediments (7 500-8 000 m) has been recorded in the Baikal basin, decreasing to 500-1 000 m at the limits of the rift system. Rifting was accompanied by basaltic magmatism of fairly uniform petrochemical composition, dominated by alkaline olivine basalts. Magmatic conduit centers and volcanic fields are located quite independently of the rift faults and basins except for in the Tunka rift valley. Rifting in Eastern Siberia is an independent geodynamic phenomenon which is thought to have no direct relation to the collision of the Hindustan subcontinent with Eurasia. The Baikal rifting is mainly driven by a local source of energy, resulting from asthenospheric upwelling, heating and gravitational instability of the lithosphere.