A licence area centred approximately 150 km north of Yunta, and bordering the south-eastern Flinders Ranges, was taken up to try to locate basinward extensions of a previously found Lower Tertiary palaeochannel sequence, in order to evaluate the channel's potential for hosting possible economic sandstone type uranium deposits. The channel, which had been discovered by Esso in 1973 within two of its scout drillholes, was successfully further defined by Marathon's drilling during June-July 1978 of 22 open rotary holes with a total penetration of 3251 m, but this drilling encountered only poorly developed channel sands in the far south-western part of EL 337, and no significant uranium mineralisation was present in them. Selected drill cuttings were assayed to confirm gamma log indications of patchy low order uranium content in the more carbonaceous and clayey lacustrine sediments, and an atypical highest value of 520 ppm U3O8 was returned from the narrow depth interval 66-67.5 m in hole WC14. Lower Tertiary deposition apparently took place in a slowly subsiding graben, with fluvial facies evident in the south-east rapidly changing to more lacustrine facies towards the north.