The accumulation of Stone Age lithic artifacts in rock fragment mulches in northern Ethiopia

Lithic artifacts buried in the soil profile may be transported to the surface during tillage-induced kinetic sieving, differential erosion, or swell-shrink cycles of clays and become part of a rock fragment mulch. Archaeologically, these manifestations are recognized as surface scatters. Although artifacts at the soil surface are difficult to relate to the local stratigraphic context, surface assemblages may provide information on lithic industries and the archaeological significance of sparsely explored regions. Through in situ investigation of surface material in 60 1 × 1 m2 plots in the Tembien district in the northern Ethiopian highlands, we show that rock fragment mulches can contain a significant number of lithic artifacts and we provide evidence for mid-Pleistocene occupation of a site. Considering that severe rill and gully erosion may be a threat to the archaeological heritage and that well-dated African Middle Stone Age sites are rare, we conclude that the region deserves more attention for archaeological research.