GEOARCHAEOLOGY OF THE DOUGLAS KORONGO SITE, OLDUVAI GORGE: PRELIMINARY RESULTS

The Douglas Korongo (DK) site is located east of the junction, between the Third and Fourth Faults in Olduvai Gorge, Tanzania. DK’s exposed cultural and faunal material-bearing strata lie between the Bed I basalt (2.0 Ma) and Tuff I B (1.86 Ma). Previous excavation by Mary Leakey revealed a wealth of fossils, stone tools, and debitage in these sediments, including Oldowan tools and some Homo habilis remains. Richard Hay originally described the sediments making up the DK site as a series of four tuffs: the lowermost a mixed silt-clay-tuff, the middle two clayey tuffs, and the uppermost a tuff inter-lensed with brown clay.

Current work at DK in concert with The Olduvai Paleoanthropology and Paleoecology Project (TOPPP) has exposed these deposits anew. Detailed study of two exposures 50 m apart confirms the presence of multiple tuffs and reveals a complex history of aggradation and landscape stability. Some thinner deposits are discontinuous over this scale, while some thicker deposits host paleosols that may be continuous throughout the site. These paleosols have well-developed blocky structure and host large concentrations of fossils. Overall the DK site appears to have been the locus of periodic volcanic ash and pyroclastic material deposition and subsequent pedogenesis, hosting a series of productive landscapes through time, and forming the set of andisols we describe here.

Profile descriptions include assessment of general grain size class, color, horizonation, and structure. We are currently analyzing profile samples with regard to pH, mineralogy, micromorphology, detailed granulometry, and ion content. Following assessment of overall site formation processes and artifact matrices here, investigation of the continuity of tuffs and paleosols throughout DK may enable mapping of paleolandscape surfaces that would have been available to hominin populations. Additionally, though all materials under investigation here are 2.0-1.86 Ma, dating and correlation of the interbedded tuffs would narrow the ages of individual deposits and potential paleolandscapes at DK.