Exploration conducted over an area stretching westwards and eastwards from Marree, along the south-western margin of the Great Artesian Basin, addressed the potential for possible economic sedimentary deposits of trona, sodium bentonite, chlorite, kaolinite, attapulgite and uranium associated with alkaline artesian spring waters rich in Na2CO3, that discharge to surface in many places there, and have apparently done so for a geologically long period of time. Dispersed bentonitic material was discovered by Consolidated Gold Fields within the unconsolidated Tertiary cover to Middle Cretaceous shales in the vicinity of Davenport Springs on its EL 346 Curdimurka adjoining the subject EL 355 to the west. However, no commercial quantities of the same mineral could be found by inspection and auger drilling of many other nearby active and extinct mound springs, although minor surface occurrences of trona and nahcolite were located around various of them, centred on the recent natural drainage channels of the springs. Near the base of the mound structures, the Marree Formation was seen to be brecciated and altered to white clay along fractures, the alteration penetrating the shale for just a few centimetres, but this clay has no economic significance either. After Comalco farmed into EL 355 in early 1978, drawn by the evidence of trona occurrences, they initially inspected all available water bore records to try to determine more closely the sites in the region where the groundwater is particularly carbonate, sulphate or chloride - enriched; next, the values for sodium carbonate were contoured to show the areas of highest ionic activity. A stratigraphic drilling programme was then undertaken to try to identify which of possibly several aquifers might be present and carrying strong brine. In November 1978, 2 vertical rotary mud holes for 280 m were drilled to basement at sites located respectively 34 km and 6 km west of Marree, and both holes were geophysically logged. This drilling proved that there are no intermediate, high salinity near-surface aquifers within the Cretaceous sequence, and thus excluded the likelihood of encountering any high Na2CO3 bearing aquifer which historically could have been responsible for the observed surface anomaly, and so it was decided by the JV partners to surrender EL 355.