Nature 316, 792 - 794 (29 August 1985); doi:10.1038/316792a0

Age of the Okote Tuff Complex at Koobi Fora, Kenya

Ian McDougall, T. Davies, R. Maier & R. Rudowski

Research School of Earth Sciences, Australian National University, PO Box 4, Canberra, ACT 2601, Australia

The Okote Tuff Complex crops out in the Koobi Fora region next to the north-eastern shores of Lake Turkana, northern Kenya. It occurs in the upper part of the 450 m thick, essentially flat lying, Plio-Pleistocene sequence of fluvial, deltaic and lacustrine sediments comprising the Koobi Fora Formation¹⁻³. Many important archaeological sites and hominid fossils, including the Homo erectus finds discussed in the accompanying papers^4,5, are stratigraphically close to the level of the Okote Tuff Complex⁶ or its correlatives, so that its precise numerical age is of great interest. Previously published isotopic ages, mainly by the ⁴⁰Ar/³⁹Ar dating technique, exhibited a very wide scatter⁷. Here we report comprehensive K−Ar data showing that pumices within one of the tuffs of the Okote Tuff Complex have an age of 1.64 0.03 Myr, which is in the earliest Pleistocene⁸.

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