Topographical Tests of Landscape Evolution Schemes, Central Australian Ranges

Abstract

Previous studies have documented the unusually long evolutionary histories of the central Australian mountain ranges (e.g., MacDonnell, Krichauff, Waterhouse, and James), including early planation (late Mesozoic); subsequent deep weathering and associated etchplanation under humid/tropical conditions; cross-axial river incision; long-term stream impression; and progressive aridity; all associated with regressive river erosion, stream capture, and epeirogenetic tectonism. The present investigation employs newly available topographic data to advance understanding of these phenomena, to test previously proposed explanations for some of them, and to discover some new geomorphological puzzles in this very interesting region. Important discoveries made by this study include (1) confirmation of the very ancient landscape elements, as demonstrated by the Tnorala impact structure (145 Ma), (2) deformations in both cross-axial and ridge-and-vale landscape profiles that reveal possible epeirogenetic influences on the topography, (3) remarkable adjustment of major river longitudinal profiles across diverse geological structures, (4) special consequences of etchplantion for the drainage evolution of “intramontane basins,” (5) the phenomenon of incised bedrock paleomeander palimpsests for both the Larapinta (Finke) and Hugh Rivers, and (6) the phenomenon of “in-and-out” gorges.