University of Tasmania

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Coastal erosion reveals a potentially unqiue Oligocene and possible periglacial sequence at present-day sea level in Port Davey, remote South-West Tasmania

journal contribution
posted on 2023-05-18, 05:58 authored by Macphail, M, Christopher SharplesChristopher Sharples, David BowmanDavid Bowman, Wood, S, Haberle, S
Cut-back of a sea-cliff at Hannant Inlet in remote South-West Tasmania has exposed Oligocene clays buried under Late Pleistocene “colluvium” from which abundant wood fragments protrude. The two units are separated by a transitional interval defined by mixed Oligocene and Pleistocene microfloras. Microfloras preserved in situ in the clay provide a link between floras in Tasmania and other Southern Hemisphere landmasses following onset of major glaciation in East Antarctica during the Eocene-Oligocene transition (c. 34 Ma). The Late Pleistocene “colluvium” preserves abundant fossil pollen of the shrub conifer genus Pherosphaera (al. Microstrobos). Assuming the parent plants had the same upper subalpine-alpine ecology as living Pherosphaera hookeriana, the microflora provides evidence for cold, wet conditions in the Port Davey lowlands during a low sea-level stand. The same data highlight the failure of Pherosphaera to regain its Pleistocene distribution during the Postglacial period. Our data are inconclusive whether Late Pleistocene conditions in Hannant Inlet were periglacial, i.e., the Oligocene sediments were turbated by freeze-thaw processes, or have been reworked by fluvial processes into the Pleistocene “colluvium”. Nevertheless, the inferred cold-climate is consistent with the former hypothesis. The sequence is sealed under cross-bedded coarse quartzite gravels of presumed Last Glacial Stage age.


Publication title

Papers and Proceedings of the Royal Society of Tasmania








School of Geography, Planning and Spatial Sciences


Royal Society of Tasmania

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Copyright 2014 Royal Society of Tasmania

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Socio-economic Objectives

Assessment and management of terrestrial ecosystems