Evidence for regionally wet conditions before the LGM in southeast Australia: OSL ages from a large palaeochannel in the Lachlan Valley

Optically stimulated luminescence (OSL) techniques have been used to obtain the first ages on Late Pleistocene channels in the Lachlan Valley, southeastern Australia. Two OSL ages from channel sand and overlying source-bordering dune sand indicate that large sinuous channels, with bankfull discharges six to eight times greater than the present river, were fully established by 34 ka BP. This conclusion is consistent with regional lake level and geomorphic evidence of cool, pluvial conditions that preceded the last glacial maximum (LGM), providing new information on a long-standing palaeohydrological problem caused by the apparent synchroneity of large river systems and regional aridity.