Contrasted morphologies of the Western and Eastern Piedmonts of the Mt Lofty Ranges, South Australia

Abstract

The Mt Lofty Ranges is a horst that evolved in two stages. The western margin developed as part of the South Australian Shatter Belt during the separation of Australia and Antarctica. Gulf St Vincent formed at this time. Though recurrently active the upland dates essentially from the Early Eocene with major uplift in the later Cenozoic. By contrast, the eastern faulted margin postdates the Middle Miocene. Also, whereas the western piedmont and upland were affected by Late Cenozoic sea level changes and all that those imply for river behaviour, the eastern sector was buttressed against such fluctuations by the massive Miocene limestone deposited in the Murray Basin immediately to the east. Consequently, the western piedmont is dominated by alluvial fans, but the eastern is complex, with well-developed scarp-foot depressions, exhumed landforms, and dunefields in some sectors.