Seismic Refraction to Identify the Extent of Archaeologically Significant Subsurface Layers Between Excavation Sites at Kathu Pan, Northern Cape Province, South Africa

A seismic refraction survey was done in June 2019 at the archaeological site Kathu Pan in the Northern Cape Province of South Africa, in order to identify and describe the extent of the sediment layers between excavated profiles. This site is characterized by karst topography with several sinkholes that have been excavated to reveal Stone Age lithics of archaeological significance. Extensive archaeological and paleoenvironmental work has been done at these excavated profiles to connect lithic assemblages to specific layers in the stratigraphic sequence and to elucidate the environmental conditions over the past 500 ka, with site KP6 dating back to at least 150 ka. Identifying the extent and the existence of these layers beyond the excavated sites will aid in better understanding past human interaction with the landscape. We analysed seismic first arrivals along a line that extended 36 m east from archaeological site KP6, and were able to identify the depth and velocity of three layers which we could correlate to the known stratigraphic sequence: an upper layer composed of soil and unsaturated sand overlaying a layer of unsaturated sand to a depth between 0.8-1.5m and a fine or compact sand layer between 2.5-3.8m. In addition, our survey also revealed the existence of a higher velocity layer lower in depth than described by the profile which we tentatively describe as carbonate bedrock.