Gombore II (Melka Kunture, Ethiopia): A new approach to formation processes and spatial patterns of an Early Pleistocene Acheulean site

To assess the integrity of Pleistocene archaeological sites is crucial in the analysis of human behaviour. Most of the Early Palaeolithic sites are in active fluvial environments where it is necessary to understand the degree of sedimentary disturbance. The analysis of the formation processes through geoarchaeological and geostatistical techniques offers new tools to evaluate if the archaeological assemblage is in autochthonous or allochthonous position. Gombore II, approximate to 850 Ka, within the archaeological and paleontological complex of Melka Kunture (Ethiopia), extends over estimated 1000 m(2) and yielded a large number of Acheulean artefacts, fossil mammal bones and two fossil hominin remains. The geomorphological setting and deposition patterns of high-energy sedimentation in a fluvial channelized environment are similar to those of many other Early Palaeolithic African sites. This is traditionally described as producing a disturbed record, with the fortuitous association of faunal remains and lithic industry driven by fluvial processes. To assess this hypothesis, we analyse here the formation processes and the spatial patterning of the remains. We apply geoarchaeological (orientation and fabric) and spatial tests (density, grouping, k-means) to the mapped archaeological surfaces and to a present-day fluvial surface. We observe substantial differences in geoarchaeological features and spatial patterning between the archaeological record (lithic materials and faunal remains) and the natural clasts of both the archaeological deposit and the bed of the present-day river. This suggests different depositional processes or temporal events. We conclude that the remains produced by the hominins did not haphazardly accumulate after extensive erosion and re-sedimentation. They rather preserve a reasonable degree of taphonomic and spatial integrity and are possibly representative of different activities.