An Oscillating Holocene Sea-level?: Revisiting Rottnest Island, Western Australia, and the Fairbridge Eustatic Hypothesis

Title
An Oscillating Holocene Sea-level?: Revisiting Rottnest Island, Western Australia, and the Fairbridge Eustatic Hypothesis
Publication Date
2005
Author(s)
Baker, Robert Graham
Haworth, Robert John
Flood, Peter Gerard
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Coastal Education & Research Foundation, Inc
Place of publication
United States of America
UNE publication id
une:2276
Abstract
There is a similarity in the pattern of Holocene sea-level change at Rottnest Island and a number of other locations in southern Western Australia. Rottnest Island was one of the field study areas that Fairbridge (1961) used to develop his fluctuating Holocene sea-level curve. Eight ¹⁴C ages obtained from fixed shell material of Serpulid tubeworms from tightly constrained inter-tidal zones are presented from Rottnest Island, and thirteen more from a transect extending 1000 km along the coast of southwest Australia. The age-elevation profiles show a consistent mid- to late- Holocene sea-level fluctuation over the entire southwest Australian region, which argues against a strong local tectonic or a broader hydro-isostatic influence. A comparison of the southwest and southeast coasts of Australia, based on fixed inter-tidal biological indicators obtained by similar methods, indicates a broadly similar mid- to late-Holoceneoscillating sea-level curve up to two metres higher-than-present. Peak levels are preceded and followed by sharp ~1 metre falls, which appear to be associated with cooling sea temperatures at ~5200 and ~3800 cal years BP. Both rising sea levels and warmer-than-present sea surface temperatures occur at all locations at ~4200 and ~6500 calyears BP, with a net sea-level fall to the present, but a slight warming beginning at ~1400 cal yr BP. There also appears to be a common pattern of species change suggestive of synchronous climatic variations. These mid-latitude fluctuations and environmental changes on the Australian coastline are similar to some events over the same period in the equivalent far-field locations of southern Brazil and southeast Asia. The synchronicity of these oscillations and their climatic underpinnings, in mid-latitude sites far from the complications of glacial isostasy, is not inconsistent with Fairbridge's (1961) basic thesis of world-wide eustatic Holocene sea-level change.
Link
Citation
Journal of Coastal Research (Special Issue No. 42), p. 3-14
ISSN
1551-5036
0749-0208
Start page
3
End page
14

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