In a search for possible economic Tertiary brown coal deposits buried in the northern half of the Walloway Basin, 4 reconnaissance holes spaced 5 km apart, with a total penetration of 773 m, were open rotary mud drilled and geophysically logged. The holes were sited principally on the basis of existing water bore stratigraphic information. Two of the drillholes intersected thin coal stringers to 3 m thick, and a third hole encountered a significant artesian aquifer (with an estimated 140 l/s initial flow rate at surface). Data from ETSA's subsequent July-August 1983 regional gravity survey carried out in the northern half of the basin, taken in conjunction with results of an earlier SADME gravity survey of the southern part of the basin, show that the ~50 km x 16 km basin outline is assymetrical in cross-section, with Tertiary sedimentation probably mainly confined to the western side by a basement growth fault lying central to the basin. Two structural prospects were identified by ETSA that might afford coal targets existing at shallower depths than the coal occurrence found previously in the SADME hydrogeological drillhole WW1 (23 m of coal below 244 m depth), and five additional drillholes were proposed to test these prospects. However, later it was decided not to proceed with this programme because of the comparatively disadvantageous depth, thickness and remoteness of the known and likely Walloway seams relative to the settings of other, competing undeveloped brown coal occurrences in the State.