The Nundroo basement drilling project was proposed in February 1987 by SADME's Regional Geology Branch as the first phase of investigation of the little known rocks of the south-western Gawler Craton. Previous drilling in this area had been restricted to a very few shallow rotary percussion holes completed within the cover sediments in a search for groundwater supplies. During the year, a campaign of stratigraphic drilling was carried out by the Branch at sites which were selected after making an interpretation of 75 line km of surveyed precursor ground magnetic and gravity data. 16 vertical rotary mud drillholes totalling 1129 m, plus 3 angled diamond drillholes totalling 670 m, were completed. SADME Nundroo 1, 2 and 3 stratigraphic diamond drillholes encountered highly metamorphosed basement garnet and magnetite-rich gneisses containing anomalous copper and iron sulphides, that are interlayered with metabasalts or metagabbros, meta-andesites or metadiorites, and various sediments that possibly are associated with past weathering of local acid igneous extrusive or intrusive rocks. All of these rocks have been subjected to granulite facies metamorphism, and then to later retrograde amphibolite facies metamorphism, at c. 1570 Ma. This age is not directly correlative with any other known South Australian orogenic event. The age of the early granulite facies metamorphism is unknown. The metabasics are anomalous in Ti and V, and are slightly anomalous in Cu, Cr and Ni. There are no similar metabasics in South Australia: however, the Nundroo basement gneisses have similar strike length, metamorphic history, protoliths and anomalous trace element content to those aspects of greenstone rocks found in the Fraser Range of Western Australia.