Stream response to Quaternary climate change: evidence from the Shoalhaven River catchment, southeastern highlands, temperate Australia

Abstract

Luminescence ages from a flight of four paired alluvial terraces in the upper catchment of the Shoalhaven River, southeast highlands, Australia, provide a record of stream behaviour throughout the late Quaternary. Ages ranging from 7 ka in the modern floodplain to nearly 500 ka for the uppermost dated terrace allow comparisons to be made of the response of streams throughout southeastern Australian to late Quaternary climatic perturbations. The alluvial record of the Shoalhaven River highlights the broad regional synchronicity of episodes of heightened fluvial activity during Oxygen Isotope Stage (OIS) 5 (terminating not, vert, similar75 ka), 60–not, vert, similar40, 30–25 and 20–15 ka. The Shoalhaven record also shows an absence of fluvial activity during the Last Glacial Maximum suggesting that southeastern Australia was most likely dry at this time as compared to northern Australia which was probably wet. Fluvial activity, while still significant, decreased substantially after approximately 60 ka suggesting a general drying of climate towards the present.