Timing of post-European settlement alluvium deposition in SE Australia: A legacy of European land-use in the Goulburn Plains

Abstract

The timing of landscape change, post-settlement alluvium (PSA) deposition and gully erosion in the southeastern Australian Tablelands remains at the centre of a long-standing discussion over the geomorphological effects of European land-use compared with Aboriginal land-use and climate change. Few quantitative studies date the onset of gully erosion and subsequent PSA deposition in the Tablelands and those that do determine the timing of landscape change for individual catchments rather than across the region. In this study, we present optically stimulated luminescence (OSL) burial ages of swampy meadow (SM) sediment and PSA from six sites spread throughout the Goulburn Plains to place better regional constraints on the timing of landscape change. PSA burial ages at each of our sample sites range between 213 and 81 years before AD 2013, the year during which all samples were collected and measured – corresponding to AD 1800–1932. All measured PSA burial ages post-date European arrival to Australia and are therefore consistent with the generic name and implied age assigned to these sediments before quantitative age estimates were available for them. We suggest, however, that the term ‘post-European settlement alluvium’ may be more appropriate in the Australian context as Aboriginal Australians were living in the Tablelands prior to European arrival. Associations between the occurrence of gully incision and PSA deposition throughout the Tablelands and climatic factors are tenuous, and we suggest that European land-use practices in the region dominate landscape evolution, which had been driven by climatic factors throughout the Holocene.