LATE QUATERNARY GEOMORPHIC HISTORY OF UPLAND VALLEYS ON THE MARGIN OF THE AUSTRALIAN DESERT

This paper presents the results of investigations of the Late Quaternary geomorphic history of upland valleys on the arid margin of western NSW, Australia. Alluvial valley fills were investigated using standard stratigraphic and sedimentological techniques. A chronology of landscape evolution of the valleys was developed by using optically stimulated luminescence (OSL) and radiocarbon determinations from valley fill sediments.

A discontinuous record of landscape change extending back about 75,000 years is evident in the valley fill of Stud Creek, draining a 30 km2 catchment east of Tibooburra in far northwestern NSW. Five major sedimentary units provide a record of depositional episodes ranging from modern, or post-European, back to the Late Pleistocene, interspersed with long periods of erosion for which there is no remaining sedimentary record.

This pattern of episodic nonequilibrium in landforming events is common in the Australian arid zone, with similar patterns being observed in stratigraphic records elsewhere in the region. However, the record for Stud Creek is the most detailed so far published for this part of Australia. It provides insights into the behaviour of upland ephemeral stream systems on the desert margin of Australia throughout the Late Quaternary, and constrains the record of occupation of the Aboriginal hunter-gatherer people who once lived there.