Lake Bungunnia — A Plio-Pleistocene megalake in southern Australia
Abstract Between 2.5 Ma and 0.7 Ma a Plio-Pleistocene megalake, Lake Bungunnia, existed in the western Murray Basin, Australia. Study of hydrologic and geologic constraints on this lake has enabled the climate of southeastern Australia during the late Pliocene and early Pleistocene to be partly quantified. Modelling shows that Lake Bungunnia could not exist under current climatic conditions, and that an average rainfall of at least 500 mm yr −1 over the catchment of the Murray-Darling river system was likely, considerably more than at present. Minor changes in climate caused large fluctuations in the shoreline of the shallow lake, which are reflected in the geologic record. Possible histories for Lake Bungunnia are suggested in the light of this evidence. Demise of the megalake heralded the onset of aridity in southern Australia, and modern landforms date from that time. Salt lakes in part of the western Murray Basin may have directly descended from Lake Bungunnia.