Reports describe the results of two attempts to use seismic refraction methods to map an unconformable subsurface interface between lithic sandstone and quartzite units within the Whyalla Sandstone. This palaeosurface is important as a locus for stratabound copper sulphide mineralisation in the Mount Gunson area. Seismic lines were shot over the Main Open Cut and Lagoon orebodies, to try to detect the interface in un-mined areas and to compare the refractor depth information with limited stratigraphic intercept data gained from prior exploratory drillholes.