High grade limestones which outcrop over a distance of some 13 miles along the front of the Flinders Ranges east of Brachina and Parachilna were sampled during the period 5th December 1963 to 16th December 1963 with the assistance of T. Amtmania, W.V. Preiss, S. Coxon and A. Corbett. The occurrence of these limestones was brought to notice during the course of regional mapping by Geologist B. Dalgarne when geochemical sampling, undertaken on a section south of Brachina Gorge, indicated the presence of a uniformly high grade bed almost 2000 feet in thickness. Being situated only eight miles east of the four foot eight and a half inch rail connection between Leigh Creek Coalfield and Port Augusta, and less than 100 miles north east of Port Augusta, the deposit was considered to be worthy of further attention. Access is readily gained via an unsealed road which connects the main northern road by way of Brachina Gorge to the Wilpena-Blinman road. The bed of high grade limestone outcrops continuously along the front of the Flinders Ranges is rugged foothills, free of overburden over a distance of some 19 miles. The bed is disected by a number of creeks which discharge on to the plains to the west and ultimately into Lake Torrens - the most important of these is Brachina Creek which has incised a deep gorge through limestones and the more resistant underlying quartzite beds which are the major ridge formers of the ranges and in which are carved the spectacular gorges of the region.