A seismic refraction survey at Roger Corner, near Yorketown on Lower Yorke Peninsula, has profiled pre-Permian bedrock and several other shallower refractors. The survey was carried out at the request of Aberfoyle Exploration Pty Ltd, licensees of EL 1018. A 2300m long north-south profile has indicated that a series of relatively flat lying Quaternary, ?Tertiary and Permian units overly a 6130-6240m/s bedrock refractor, 337m deep in the north to 378m in the south at an average dip of 1°. The velocity of this refractor is typical of Archaean metamorphic basement, although the possibility that it represents a high-speed Cambrian carbonate unit cannot be dismissed.