Two seismic refraction surveys were carried out by the SADM for Santos, on spreads laid out 27 miles north of Port Augusta, following the finding of traces of oil in the Tertiary sediment samples recovered from that company's Wilkatana 1 stratigraphic well. The aim was to investigate the possibility of a basement high being present there, over which the Tertiary sands may be draped in anticlinal form, thus forming a potential petroleum trap. The first survey spread, centered on the site of Wilkatana 1, was recorded to establish the local dip direction and angle of dip of the basement. The second survey was subsequently located 4500 feet away in an 'updip' position, to try to obtain information about the shallowest depth of the inferred basement high. The signal passing through a limestone layer occuring at 470 feet depth was not refracted, but nevertheless, based on limited data, the top-of-basement unconformity depth was provisionally calculated to lie at between 540 and 720 feet. Further seismic interpretation work was deferred, pending results of a velocity determination of the limestone.