The last million years around Lake Keilambete Western Victoria Australia

Abstract

Pollen records from sediments preserved in the older volcanic crater maars of Lake Terang and Pejark Marsh, situated close to the more recent and intensively researched younger maar containing Lake Keilambete, provide a basis for understanding the development of the present landscape of western Victoria in relation to past vegetation evolution, climate change and volcanic activity. Despite dating uncertainties and discontinuities, the record from Lake Terang may cover much of the last five hundred thousand years (500 ka) while that from Pejark Marsh is fission track dated to between about one million years (1 Ma) and 700 ka. An analogue method is used to provide measures of past vegetation and precipitation. Overall, the Early Pleistocene vegetation was dominated by herbaceous taxa with an open canopy of trees composed of more Callitris and fewer eucalypts than today. The climate was drier, never achieving rainfall levels higher than present. Since this time the vegetation and climate displayed greater variability, probably in relation to global shifts between glacial and interglacial conditions, with interglaciat peaks often showing the development of eucalypt forest and expansion of cool temperate rainforest. Through the whole period, climate appears to have been the dominant influence on vegetation with no detectable impact of volcanic activity.