An area bordering and including the southern end of Lake Eyre North was taken up by Comalco to cover a possible Miocene lacustrine palaeodepositional environment for authigenic sodium carbonate (trona) sedimentary deposits. Actively discharging artesian aquifer mound springs in the vicinity are considered to be potential sources for the mineralisation. At the time a decision was made to surrender the licence ground, the trona mineralisation potential still remained untested because of protracted difficulties in gaining access onto the poorly consolidated lakebed for the purpose of conducting drill sampling of shallow subsurface sediments, although a reconnaissance of the dry lakebed east of Halligan Bay was carried out in July, and hand augering was attempted near a mound spring. One 3 m deep hole was cut through the Holocene sedimentary sequence, with the hole ending in a dolomite unit assumed to be Tertiary Etadunna Formation. An attempt to use two available small, lightweight hovercraft to give access to more distant and (softer) prospective parts of the lake surface proved unsuccessful because of mechanical failure of this equipment, creating a dangerous situation for the personnel involved in a awkward and slow retreat on foot to the lake shoreline. The practicability of perhaps using better-designed such transport means to achieve access remains open, but is not presently seen as being economically viable.