Extract

At the Geological Society Symposium Professor Brock gave an informal account of the work of the palaeomagnetic laboratory at the University of Nairobi in relation to the magneto-stratigraphy of the East Lake Turkana area. Results from material collected up to the end of the 1972 season are already published, and do not warrant a further paper. The main results are given in the paper by Brock & Isaac entitled ‘Palaeomagnetic stratigraphy and chronology of hominid-bearing sediments east of Lake Rudolph, Kenya’ published in Nature in 1974 (Vol. 247, pp. 344–8). A more detailed account with more descriptive material and a greater emphasis on the basic principles of magneto-stratigraphy is given in the chapter by Brock & Isaac entitled ‘Reversal stratigraphy at East Rudolf’ in the Wenner-Gren Symposium volume, Earliest Man and Environments in the Rudolph Basin: Stratigraphy, Paleoecology and Evolution (edited by Y. Coppens, F. C. Howell, G. L1. Isaac & R. E. F. Leakey, Chicago University Press, Chicago, 1976 ). The results given in the above two papers are in broad general agreement with the isotopic dates obtained by the Fitch-Miller group.

More recently, debate has arisen about the age of the KBS Tuff (see elsewhere in this volume), and palaeomagnetie collections made in the 1973 and 1974 seasons obviously bear upon this. These collections are being measured in the Stanford laboratory of Professor Alan Cox, and it is already clear that some of the samples have suffered magnetic overprinting, and interpretation will be less simple than was first