Abstract:
Development of the Nowranie Caves includes both phreatic and vadose components, with prominent influences on cave geomorphology exerted by joints, bedding and past changes in watertable levels. Active circulation is occurring within a phreatic conduit at moderate depth (22-30 m) below the level of the present watertable. Slugs of flood water can penetrate well into the flooded section of the cave, and it appears that dissolutional enlargement of the conduit may be occurring under present conditions. Speleogenesis in Nowranie Caves incorporates deeper phreatic processes in addition to shallow phreatic (i.e. watertable) processes. A series of three fossil, or occasionally re-flooded, phreatic horizontal levels in the Nowranie Caves correspond with similar levels in other Camooweal caves, and reflect a regional pattern and multi stage history of watertable changes linked with cave development. The stacked series of cave levels may reflect episodic uplift, wetter climatic episodes, or a combination of both - possibly dating from early to mid Tertiary times. Caves and dolines are the major points for groundwater recharge in the Camooweal area, and these are susceptible points for injection of contarninants into the groundwater system. A climatic and distributional relict, and locally endemic, fauna is present in the groundwater. The Nowranie Caves, and Camooweal area generally, has conservation significance as a karst hydrogeological and ecological system that has preserved a history of regional landscape and faunal evolution in northern Australia during the Quaternary.