Pre‐Quaternary landscape inheritance in Australia

Abstract

Palaeogeographic reconstructions indicate that parts of the Australian continent have been subaerially exposed for hundreds of millions of years. Some landforms and regolith are demonstrated to be at least 300 million years old, but their persistence at or near the surface is inconsistent with long-term denudation rate estimates based on cosmogenic nuclides and apatite fission track thermochronology. Burial and exhumation are suggested as significant preservation factors, in conjunction with prolonged tectonic stability and a shift to more arid climatic regimes in the Cenozoic.

Antecedent controls on river character and behaviour in partly confined valley settings: Upper Hunter catchment, NSW, Australia

“…Antecedent controls on contemporary river character and behaviour are particularly prevalent in this tectonically-passive landscape setting where preservation of palaeovalleys and palaeosediments is common (Bishop, 2007;Pillans, 2007). When placed in context of the spectrum of river diversity found in partly confined settings, the examples highlighted here would be considered "inactive" in terms of their capacity to adjust and the recurrence of floodplain formation and reworking.…”

“…They found that only localised adjustment to channels and floodplains had occurred in partly confined valleys and that the imprint of human disturbance has been relatively limited. Geological and climatic controls ensure that there is significant geomorphic memory in this old, slowly downwearing landscape (Pillans, 2007) and that contemporary processes and forms are not always the result of current climatic conditions or human-induced impacts.…”

“…Various layers of antecedence can impact on contemporary process-form associations. At the broadest scale, geological controls including lithology, tectonic history, and rates of landscape dissection and denudation dictate the shape and confinement of a valley (Fryirs, 2002;Miller, 1995;Pillans, 2007;Tooth et al, 2002). Inset within this, climate controls rates of sediment and discharge supply, and vegetation cover, resulting in rivers with differing morphologies.…”

Landscape age and soil fertility, climatic stability, and fire regime predictability: beyond the OCBIL framework

“…Not surprisingly, Old and Ancient Landscapes are widespread in Australia (e.g. Jutson 1914;Twidale 1997;Pillans 2007;Vasconcelos et al 2010). In fact many of the Australian landscapes would qualify as old (following our criteria), and the Kimberley Plateau (northern top of Western Australia) is among the oldest continuously exposed landforms on Earth, sub-aerially exposed since the Precambrian-more than 540 Ma (Ollier et al 1988;Gale 1992;Pillans 2007).…”

“…Jutson 1914;Twidale 1997;Pillans 2007;Vasconcelos et al 2010). In fact many of the Australian landscapes would qualify as old (following our criteria), and the Kimberley Plateau (northern top of Western Australia) is among the oldest continuously exposed landforms on Earth, sub-aerially exposed since the Precambrian-more than 540 Ma (Ollier et al 1988;Gale 1992;Pillans 2007). Yet the temporal scale discrepancies between the age of the surface and omnipresent rejuvenation processes give rise to nontrivial questions such as: Is the long-term tranquil geological period of any importance to the evolution of plants, the persistence of old lineages, or to plant community assembly?…”