K-Ar age estimate for the KBS Tuff, East Turkana, Kenya

Abstract

Stone tools and numerous vertebrate fossils including hominids, have been found in close stratigraphic proximity to the KBS Tuff, whose age has been the subject of much debate. Concordant K-Ar ages, averaging 1.89 ± 0.01 Myr, are reported on anorthoclase phenocrysts from 13 pumice clasts collected from within the KBS Tuff or its correlatives. We believe that this age is the best estimate currently available for the time of formation of this important marker horizon within the East Turkana Basin. © 1980 Nature Publishing Group.