A licence area covering the flat alluvial Paralana Plains extending out eastwards from the northern Flinders Ranges was taken up by the the consortium of Exoil NL, Petromin NL and Transoil NL to explore for possible economic buried occurrences of sedimentary uranium mineralisation. This area was regarded as being highly prospective because it lies adjacent to the known primary uraniferous Mount Painter district. However, no surface indications of the presence of any mineralisation exist, so the exploration method adopted was to conduct reconnaissance rotary drilling along traverses running outward from the edge of the Ranges. After 18 months of work, during which time 34 barren exploratory drillholes had been completed, some very significant sedimentary uranium deposits (with downhole gamma log radioactivity greater than 300 API units, and uranium assays, by XRF, of better than 2 lbs per short ton over 12 inches or more of sampled drill core) were discovered by drilling in Early Tertiary palaeochannel sediments around the Four Mile Bore on the Paralana Plains, within an area of about 12 square miles, and, based on the results of continuing intensive appraisal drilling, there is every likelihood that the ore will prove economic. Exploratory rotary plug drilling on one mile-spaced centres along creeks and tracks encountered the first highly anomalous radioactivity in holes 186-20, -21 and -22 in November 1969, during analogue gamma ray downhole probing. The radioactive anomalies were confirmed in early 1970 by corehole 186-22A drilled 10 feet away from the logged-only hole 22, when fine-grained uraninite was tentatively identified in drill core samples. Since this initial discovery time, up to three rotary drilling rigs have been employed to step out drill each successive deposit on 200 foot grid spacings to extend and prove its U3O8 reserves. Since late 1969, 339 rotary holes totalling 164,639 feet have been put down in the Beverley prospect area, of which 13,371 feet have been cored. Conventional full-hole cores were diamond cut in certain of the recently drilled holes to obtain samples for sieve analysis for a solution mining study; other selected holes were also diamond cored to give samples for tests related to open cut mining studies.