The area north of Lake Eyasi, the Vogel river area, is one where the effects of rift movements, continental warping, and volcanism have interacted. Tilting of the Serengeti peneplain, formation of the Eyasi scarp, and the beginnings of the Giant Craters occurred in the Pliocene and early Pleistocene followed by deposition of volcanic ash entombing mammals, a lava flow, intensive denudation, and a later important period of rift faulting.