Preliminary luminescence dates for archaeological sediments on the Nullarbor Plain, South Australia

Koonalda Cave, Nullarbor Plain, South Australia – issues in optical and radiometric dating of deep karst caves

“…However, the dating for Allen's Cave did not suffer this phenomenon and did indeed extend human occupation of the Nullarbor region to circa 40,000 years (Roberts et al, 1996). This alone has added some weight to Gallus's original speculation of 30,000 years or more for Indigenous use of Koonalda Cave.…”

“…With the introduction of luminescence dating techniques it was hoped that the problems of vertical displacement and/or contamination of charcoal could be overcome. However, this methodology is equally challenged by very low dose rates and incomplete and inconsistent bleaching of ancient sediments (Roberts et al, 1995, 1996and Gillespie, 2002. These traits are typical of the Nullarbor Plain sediments.…”

“…Optical dating was performed on all samples from both sites but only those from Allen's Cave proved viable. The Koonalda Cave samples were found to suffer significant discrepancies between optical and calibrated 14 C dates when surface sediments were tested (Roberts et al, 1995 and1996). It was stated that bleaching problems existed in water lain sediments transported deep into the cave and this could potentially overestimate the actual age;…”

“…In the early 1990s, a series of sediment samples were taken from Koonalda Cave and from a nearby open rock shelter, named Allen's Cave (Cane, 1995;Roberts et al, 1995 and1996). The latter has formed from a collapsed doline offering a modest overhang rather than a deep karst cave.…”

“…Although the Nullarbor Plain is characteristically flat, arid and treeless, the archaeology indicates that humans were present by at least 35,000 years ago (Roberts et al, 1996 andSmith, 2013). This time span includes the Last Glacial Maximum (LGM) which held the sea some 150-200 km further to the south of the Plain and consequent particularly inhospitable conditions.…”