Evolutionary Geomorphology of Australia and Papua: New Guinea

Abstract

By means of examples it is demonstrated that much of the geomorphology of Australia dates back to early Cenozoic, Mesozoic and even Palaeozoic times. Papua-New Guinea is built of several fragments that had different histories before they collided with the Australian plate, and it is meaningless to construct a geomorphic history on the present map of the country. Despite signs of geomorphic youth, such as Pleistocene granite and gneiss domes, even Papua-New Guinea has many relic landforms. Conventional models of geomorphic evolution are evaluated and it is considered that process studies, dynamic equilibrium, and even cyclic theory and uniformitarianism, are inadequate for the time-scale involved and the many unique events recorded in landscape history. Evolutionary geomorphology, a branch of evolutionary earth science, is suggested as a more appropriate concept. IT is well known that Australia is an old continent, worn down over a long period of continental erosion to become the flattest continent. Over the past few years the development and application of absolute dating techniques has put the geomorphic history on a firm basis with a large number of accurate dates. It has been found that the development of the Australian landscape that we see today started before the break-up of Gondwanaland, which created the present continents of the southern hemisphere, and that there are significant relationships between landforms and continental drift. But even more important than the decipherment of this long geomorphic history is the light it throws on geomorphic concepts. Many of the ruling theories of today seem to be inadequate on the long time-scale, and a new view of the evolution of ancient landscapes is required that can accommodate the many unique events that occur in such long spans of time. PALAEOGEOGRAPHY