Late Quaternary environmental change and human impact around Lake Bolac,western Victoria,Australia

The late Quaternary history of the Lake Bolac region is reconstructed from sedimentary and pollen analysis of lake and swamp sequences and is supported by archaeological remains from lunette sediments. Freshwater deposits recovered from lake Turangmoroke appear to date from the last glacial period, when the vegetation was composed of herbfield and grassland. Subsequent dry conditions at the end of the Pleistocene caused the deflation of some accumulated sediments. On refilling, the lake had become saline. As moisture availability increased, casuarina woodland, dominated by Allocasuarina verticillata, became the regional vegetation cover. Domination by casuarina ended ca. 8000–7000 yr BP, probably as a result of rising saline ground-water tables. Casuarinas were replaced to some degree by eucalypts, augmented by the development of a riverine Eucalyptus camaldulensis woodland. Swamp deposition commenced in the channel of neighbouring Fiery Creek at ca. 4000 yr BP, most likely as the result of a reduction in stream flow with decreased precipitation. Despite suggestions of significant impact on the vegetation by Aboriginal people from other sites in southeastern Australia, there is no evidence of any alteration here from periods of occupation dated to around 13000 yr BP and after 3500 yr BP. The period of European occupation, though, is marked by significant changes in fire patterns, reduced tree cover, loss of floristic diversity, increased erosion rates and salinity levels, and decreased water levels.