Neotectonics and Australian Biogeography
Australia is the flattest continent on Earth and has a wide range of different landforms, making it an ideal place to investigate the impact of neotectonics (continental tilting and dynamic topography) on bioregionalisation. It is highly likely that conti
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Neotectonics and Australian Biogeography
Abstract Australia is the flattest continent on Earth and has a wide range of different landforms, making it an ideal place to investigate the impact of neotectonics (continental tilting and dynamic topography) on bioregionalisation. It is highly likely that continental tilting and dynamic uplift together have driven the biogeography of Australia since the Palaeogene.
3.1 Australia: The Titling Continent and the Birth of Biomes The current narrative that the evolution of Neogene Australian biogeography, particularly its biomes, is a result of Australia’s slowly drifting north into a new climate zone is too simplistic and needs to be recast in regards to biotectonics. Recent advances in geophysics and geomorphology have shown that dynamic topography due to intra-plate stresses has tilted the Australian continent along a NW-SE axis. This tilt, and the dynamic topographic changes that it has created, has had a greater effect on bedrock erosion than climate (Quigley et al. 2010). Bedrock erosion, due to changes in topography, is a result of weathering and later erosion due to drainage. The effects of drainage within the Australian continent are two-fold. Firstly, drainage directs water towards areas lower in altitude, thereby creating watersheds that conserve temperate and aseasonally wet biomes and create new monsoonal biomes. Without such watersheds, areas on the northern and eastern seaboards would be drier, possibly arid. Secondly, changes in topography have created drier regions such as an arid plateau in Western Australia with a reduced water catchment area and a lower arid basin between two watersheds in eastern Australia. While decreasing or increasing rainfall clearly has a general effect on vegetation (and thus biotic) patterns, the way in which that water is distributed has a direct influence on what grows where. It would be more accurate to attribute the evolution of Australia’s biomes to a tilting continent rather than to a continent slowly moving north into a drier climate.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2020 M. C. Ebach, B. Michaux, Biotectonics, SpringerBriefs in Evolutionary Biology, https://doi.org/10.1007/978-3-030-51773-1_3
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3 Neotectonics and Australian Biogeography
3.1.1 Introduction to Australia’s Biomes For over 150 years, climate has been considered the driving force behind Australian bioregionalisation. In 1889 Ralph Tate mapped three of Australia’s endemic flora onto a “Rain Map of Australia” using average rainfall (Fig. 3.1). The Euronotian and Eremaen regions were proposed using the “line marking the 20-inch rainfall […] which embraces the distinctive features botanically and physically of the tract exterior to the granite table land” (Tate 1889, p. 316). The autochthonous (Southwestern) region was similarly proposed, although the 10–25 in. and 25–50 in. lines “are narrowly separated”. Tate’s map was adopted in 1896 by Spencer for the fauna divisions of the Australian region using “the pre
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