History of Australian aridity: chronology in the evolution of arid landscapes
Published:January 01, 2010
Australian climate and vegetation, known from marine and lacustrine sediments and fossils, varied dramatically throughout the Cenozoic Era, with several warm reversals superimposed on overall drying and cooling. A suite of landforms, including stony deserts, dunefields and playa lakes, formed in response to the advancing aridity but their age generally remained uncertain until fairly recently, owing to a lack of suitable dating methods. Within the last 5 years, the chronology of Late Quaternary fluctuations of lakes, dunes and dust-mantles has been established by luminescence dating methods, and mid-Pleistocene onset of playa conditions in a few closed basins has been estimated using palaeomagnetic reversal chronology. Only recently has it been shown, by cosmogenic isotope dating, that major tracts of arid landforms including the Simpson Desert dunefield, and stony deserts of the Lake Eyre Basin, were formed in early Pleistocene and late Pliocene times, respectively. These landscapes represent a stepwise response to progressive climatic drying and, speculatively, were accompanied by biological adaptations. Recent molecular DNA studies indicate that Australia's arid-adapted species evolved from mesic-adapted ancestors during the Pliocene or earlier, but whether speciation rapidly accompanied the development of stony deserts and other arid geomorphological provinces awaits further studies of arid landscape chronology.
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Australian Landscapes provides an up-to-date statement on the geomorphology of Australia. Karst, desert, bedrock rivers, coasts, submarine geomorphology, biogeomorphology and tectonics are all covered, aided by the latest geochronological techniques and remote sensing approaches. The antiquity and enduring geomorphological stability of the Australian continent are emphasized in several chapters, but the cutting-edge techniques used to establish that stability also reveal much complexity, including areas of considerable recent tectonic activity and a wide range of rates of landscape change.
Links to the biological sphere are explored, in relation both to the lengthy human presence on the continent and to a biota that resulted from Cenozoic aridification of the continent, dated using new techniques. New syntheses of glaciation in Tasmania, aridification in South Australia and aeolian activity all focus on Quaternary landscape evolution.
This major synthesis of Australian geomorphology is dedicated to Professor John Chappell (The Australian National University) and Professor Martin Williams (University of Adelaide).