Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise
Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field) locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution.
Dougherty, Amy J.
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Thomas, Zoë A.
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Fogwill, Christopher
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Hogg, Alan
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Palmer, Jonathan
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Rainsley, Eleanor
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Williams, Alan N.
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Ulm, Sean
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Rogers, Kerrylee
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Jones, Brian G.
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Turney, Chris S.M.
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17 July 2019
Dougherty, Amy J.
5ac62411-d5ac-4fde-881d-8d2b9260e057
Thomas, Zoë A.
4b512d3a-3478-4270-9fdd-61256aa640d3
Fogwill, Christopher
3bad6ae9-5a6d-467e-b523-9d5ed0147455
Hogg, Alan
11978083-6632-42e2-ac46-4e0f9cd709c9
Palmer, Jonathan
7b720b70-9c25-4ab7-bfaf-23f4be7cf9a8
Rainsley, Eleanor
4fe1e6f6-b8c2-46b3-8e94-1149b980a55a
Williams, Alan N.
1cb0b99a-5e2d-4f60-8c0f-7f672c48736d
Ulm, Sean
476924d3-845a-4489-aca0-5cc3876b7d00
Rogers, Kerrylee
03b62eb0-86e6-4740-b083-d75e43eed714
Jones, Brian G.
ccb52786-d78e-410f-a21b-ddd3a0b3f483
Turney, Chris S.M.
5149b57c-77c2-4375-97a2-a4f00aa74d97
et al.
(2019)
Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise.
PLoS ONE, 14 (7), [e0218430].
(doi:10.1371/journal.pone.0218430).
Abstract
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field) locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution.
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Accepted/In Press date: 3 June 2019
Published date: 17 July 2019
Additional Information:
Funding Information: This work was supported by grants from the Australian Research Council (project numbers FL100100195, CE170100015, and FT120100656). Alan Williams is employed by Extent Heritage Pty Ltd (AHMS), as Associate Director, Aboriginal Heritage Team Leader. However, the works submitted to PLOS One are the product of Alan’s academic research, and have no relationship to, or influence from, AHMS. Alan undertakes this research in his own time, and has received no financial, or other, support in the development of this works from AHMS. They similarly have had no involvement in the development, submission or review of the manuscript. Extent Heritage Pty Ltd (AHMS) provided support in the form of salary for author AW, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section. This work was supported by Australian Research Council (FL100100195 and CE170100015). We thank Professor Christopher Bronk Ramsey at Oxford University for his advice with OxCal modelling and John Southon from the University of California for measuring the 14C/12C ratios. SU is the recipient of an Australian Research Council Future Fellowship (project number FT120100656). Special thanks to Robert and Ann Young for the guided tour of the site and photos taken of it after the 1978 storm (one featured in Fig 2A) as well as Robert Turney for his assistance in the field.
Publisher Copyright:© 2019 Dougherty et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Local EPrints ID: 476045
URI: http://eprints.soton.ac.uk/id/eprint/476045
ISSN: 1932-6203
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Date deposited: 04 Apr 2023 17:00
Last modified: 18 Mar 2024 04:10
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Author:
Amy J. Dougherty
Author:
Zoë A. Thomas
Author:
Christopher Fogwill
Author:
Alan Hogg
Author:
Jonathan Palmer
Author:
Eleanor Rainsley
Author:
Alan N. Williams
Author:
Sean Ulm
Author:
Kerrylee Rogers
Author:
Brian G. Jones
Author:
Chris S.M. Turney
Corporate Author: et al.
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