3 diamond and 15 rotary-percussion holes were drilled in 1987 by CRA within EL 1330 on the southern part of the Field (PSF), this licence having been granted to the company for the exploration of strata below 50 metres depth in the subsurface. The authors therefore monitored the company's drilling program so as to record the geology of the top 50 metres of each hole. The resulting samples and logs from this interval were made available for public inspection. No precious opal was found. The finely ground samples made appraisal of any opal potential difficult, but useful stratigraphic information was obtained. Bulldog Shale was encountered in all holes, but weathered, bleached claystone, the host rock for opal at Coober Pedy, was absent in 4 holes and very thin near the southern margin of the PSF. Deep, weathered profiles, favourable for precious opal, were encountered in holes north and east of Leonard Rise and south of Olympic field. Cadna-owie Formation sand occurring at shallow depth SSE of Fitzgerald Dam is suitable for use as concrete sand. Similar sand is expected to subcrop around Fitzgerald Dam aggregate quarry, and further investigation is recommended.