ABSTRACT
The geological sequence of Olduvai Gorge needs to be summarized briefly in order to see recent finds in their proper perspective. A number of oscillations in deposition led to temporary land surfaces which were inhabited by mammals, including Hominidae, at irregular intervals, but the main deposits of Bed I are lacustrine with fish, crocodile, and hippopotamus remains. The major climatic, faunal and geological break occurs near the base of Bed II and not, as previously thought, between Bed I and Bed II. The geological age of Bed I is shown by its fossil fauna of which we now have a large number of specimens in good condition and which have been found in situ at different levels. The Zinjanthropus skull, which is that of a young male, seems to represent a type of Australopithecine which is different from all the known South African representatives of this subfamily, whether they be Australopithecus or Paranthropus.
