National Geographic : 1970 May
Staff members probe rock like soil at different depths. Here, 15 miles northeast of Koobi Fora, Kay Behrens meyer found what the author identifies as crude cutting and chopping tools of basalt. Their bed of volcanic ash was dated by an argon analysis technique, which measures radioactive change to determine the ages of geological strata. Laboratory tests showed that the tools were buried some 2.6 million years ago, 850,000 years before those at Olduvai. Tantalizing puzzle absorbs the author and Nzube Mutwiwa, who piece together the shattered cranium of what Richard Leakey believes may be a form of early man. It lay with sedi ments and fossil fauna similar to those in the tool strata (below) a score of miles to the south. Though face and jaws are missing, the curvature and volume of the cranium will provide evidence for eventual reconstruction of the skull. Chip off an old, old block: A rock flake perhaps left by a prehistoric tool-maker gets a protective coating of plastic be fore its removal from volcanic ash. One of man's ancestors may have squatted here to make an implement with which he could cut meat from animal carcasses.