As part of uranium exploration being carried out over the oldest basement rocks forming inliers to the south-eastern Gawler Craton, an airborne scintiilometer survey was flown across the Port Lincoln district during November-December 1968 along north-south lines spaced 1000 feet apart, with a sensor mean flight elevation of 400 feet. Isoradioactivity maps were prepared by the survey contractor for Bi214 (U), Bi214/Tl208 (U/Th) and Bi214/K40 (U/K). Noranda's interpretation of these maps delineated 39 low order anomalies that are apparently emanating from laterites and/or Archaean basement outcrop, but all were downgraded by Unimin's follow-up ground inspections and scintillometric traverses, which did not observe any uranium mineralisation and could not identify any significant (>100 counts per 2 seconds) radiometric total count anomalies. The majority of the radiation that was recorded at surface seemed to originate from the lower horizons within thicker lateritic cover, while the readings obtained over exposed Archaean basement occurred along foliation surfaces and joint planes in granitised, incipiently brecciated gneiss units.