In a search for possible economic heavy mineral - bearing buried Tertiary beach sand deposits, similar to the recent Golden Grove discovery made in Eocene fluviatile sediments of an adjacent sub-basin, 20 vertical percussion stratigraphic drillholes totalling 559 m were drilled in the Owen, Hamley Bridge and Roseworthy areas of the northern Adelaide Plains Sub-basin. All of the drillholes encountered varying and generally less-than-expected thicknesses of Tertiary sediments, and were terminated in Adelaidean basement. Only trace amounts of heavy minerals were found in a few drillholes near Roseworthy, but the occurrences were deemed to be of insufficient grade and buried too deeply to warrant further investigation. Useful subsurface structural and sedimentological information was gained concerning the mode of deposition of local Tertiary sediments, which has considerably modified but effectively validated the original exploration model.