A SADM project to attempt to determine the ages of the youngest granites of the Gawler Block, of its north-western margin, and of known subsurface granites in the Officer and Eucla Basins, was initiated with Amdel in July 1969. The project aims to newly delineate the positions of the northern and western margins of the Block by comparing isotopic dates with results obtained from rocks of the adjoining Musgrave and Yilgarn Blocks, and to establish the age relationships between the granites of northern Eyre Peninsula and the Gawler Range Volcanics, so as to resolve conflicting field mapping evidence of their relative ages. A thin section of each rock sample was prepared by Amdel and examined petrologically in order to determine the sample's suitability for age determination studies. Thereafter mineral separation of biotite and amphibole concentrates in selected samples was carried out to provide a suite of samples for K/Ar isotopic analysis. The localities of samples collected for testing are recorded on aerial photos and airphoto mosaics held by project co-manager SADM. Geographically these localities include: Gibraltar Rocks; Point Riley; Moonta; Spilsby Island; Burkitt Hill; Corunna Hill; Lake Gilles; Bitalli Dam; Cunyarie Rocks; Pearson Island; Dangerous Reef; Front Penas Dam; Thurlga; Wudinna Hills; Waulkinna Hill; Corrobinnie Hill; Pordia Hill; Cocata Hill; Kolballa Hill; Pildappa Rocks; Charkulda Hill; Yarwondutta Rocks; Nunyah Rockhole; Wallala Hill; Wirrulla Hill; Parla Peak; Curtinye Hill; Thevenard Jetty; Cape Vivonne; Point Sinclair; Rocky Point; Point James; Point Labatt; Calca Bluff; Mount Cooper; Point Drummond; Royston Head; Daly Head; Corny Point; Beatrice Rock; Hart Island; Glenloth; Nuckulla Hill; Childara Dam; Four Hummocks; Yangoonaby Rockhole; Mitcherie Rockhole; Inila Rockhole; Ifould Lake; Lake Tallacootra; Fowlers Bay; Port Lincoln; Mount Hope; Flinders Island; Saint Francis Island; Evans Island; Winceby Island; Althorpe Island; South Neptune Island; Wedge Island; Camel Hill; Arthurton; Port Vincent; Point Pearce; Maitland; Depot Creek; Lake Bring; Port Victoria; Wallaroo; Commonwealth Hill; Four Hummocks Island; Greenly Island; Anxious Bay; Coffin Bay.