Among the data reported are an age of 1444-1730 m.y. for the close of the Amgaon orogenic cycle, 1330 m.y. for the close of the Sakoli cycle, 864-996 m.y. for the Sausar orogeny, 862-950 m.y. for the age of the deformation and metamorphism of the northwestern part of the Sakoli synclinorium, an age of about 1200 m.y. for the Nandgaon folding phase, and an age of approximately 600 m.y. for the Khairagarh phase. Sediments of the Sausar and Sakoli groups are post-Amgaon in age and were deposited in separate basins whose tectonic histories differed. In the Bastar area, the Bailadila orogenic cycle is dated as approximately 2100 m.y.