Pliocene and Pleistocene sites in southern Narok District, southKenya.

Abstract

Survey in southwest Kenya above the western margin of the Gregory Rift Valley since 1994 has led to the discovery of LSA, MSA, Acheulean and possible Oldowan occurrences, as well as fossil-bearing sites representative of the early Pliocene. A long sedimentary sequence of airfall and waterlain tuVs, fluvial and lacustrine sediments and paleosols is exposed in the region of the confluence of the Ewaso Ngiro, Narok, Seyabei, Ntuka and Olonganaiyo rivers. At Lemudongo, a total of 278 well-preserved fossil bones and teeth of a variety of species including carnivores, primates, suids, bovids, hippopotamids, crocodilians, hyracoids and rodents, were collected in one day along a 70 m area of sediment outcrop. Three potentially datable tuVs are stratified within this 6 m-thick fossil-bearing paleosol. The presence of Nyanzochoerus kanamensis suggests this locality is older than 2•5 m.y.a. Four Acheulean sites have low densities of handaxes and cleavers, mainly made on phonolite, basalt and quartz. None are clearly in primary context. Excavations at Ntuka River 3 have yielded a long sequence of new Early LSA microblade industries in discrete horizons that have high densities of well-preserved bones and teeth of equids, bovids, micromammals and humans. Paleosol stable carbon and oxygen isotope analysis at this site demonstrate substantial environmental changes through time in the 7•5 m sedimentary section. In the Ntuka area, Late Quaternary sediments contain numerous in-situ early and late MSA and early LSA sites with well-preserved faunas, a penecontemporary fossil carnivore den site and other fossil-bearing sites with minimally fragmented faunas associated with low artefact densities. This provides a rare opportunity to compare faunal and lithic resource exploitation patterns through time during the Middle and Early Later Stone Age, and to compare faunal exploitation patterns of humans and carnivores on the same landscape.