In mid-1980, CRA Exploration took out four mineral tenements in the Polda Basin area of western Eyre Peninsula to explore for Tertiary and Jurassic lignites and also for possible Permian sub-bituminous coal. Interest in this area had been generated by the 1977 discovery by ETSA and SADME of the Jurassic Lock Coalfield in the central part of the basin, and by more widespread reported lignitic intervals encountered in previous company and SADM/SADME exploratory drilling and in private water bores sunk within the basin. An initial CRA assessment of these historic data outlined prospective sites to be tested by drilling, while detailed gravity surveys were undertaken over the basin's northern margin fault to define basement topography. Seventy rotary mud holes (including 4 partially cored holes) for a total of 7922 m (197.8 m cored) were progressively drilled into the Polda Basin sediments. The work included sixteen open holes and 2 partially cored holes that were drilled over a fault bounded sub-basin newly identified in the Tuckey EL 687 area. Here the thickest lignite intersections were a 15.3 metre thick Eocene seam from 221 m depth in drillhole 81LRM41, and an 8.9 metre thick Eocene seam from 60 m depth in drillhole 80LRM5. Overall, this drilling indicated a potential lignite resource of 220 million tonnes, of which 140 million tonnes occur at depths in excess of 200 m. The resource quality is comparable to that of other South Australian lignites, but its greater depth of burial currently precludes further exploration. At the majority of Polda Basin drillsites tested, only minor lignite and/or coal potential was encountered, with seams being generally very thin, of poor quality and quite discontinous laterally. Moreover, within the CRA licences, the drilled Permian sedimentary section was everywhere found to be non-prospective for well-developed carbonaceous facies. Apart from the coal search, the recent intersection of vast amounts of halite within Lower Palaeozoic sequences in the Mercury 1 oil exploration well drilled in the offshore Polda Basin had caught CRA's interest for finding potash salts associated with similar evaporitic sequences in the Tuckey EL 1054 area. A 17 km long seismic traverse completed by SADME in 1981 over this area had indicated the presence of pre-Permian sediments. An investigative 1398 m deep rotary-mud and diamond drillhole put down near this seismic line by CRA in late 1982-early 1983 intersected 793 m of ?Cambrian argillaceous red beds and basalts, but no evaporitic sediments were encountered. Subsequent stratigraphic correlations of this sequence with those seen in holes drilled in the offshore Polda Basin and in the neighbouring Officer Basin suggests that evaporites, if present, would occur below the basalts at the base of the CRA hole. There remains uncertainty whether any evaporites exist in this part of the basin, and on present knowledge further exploration for potash cannot be justified. In addition to the above two major work programmes, CRA during 1982 also conducted scout drilling of magnetic anomalies within the EL 1032 McLachlan area (11 aircore holes, total 664 m), targeting base and precious metal mineralisation in Precambrian basement. A variety of magnetic rock types from fresh and weathered metasedimentary units were intersected and sampled for assay, but no anomalous values were returned.