1. Reply to the comment by Dougherty, A.J. on "Relative sea-level records preserved in Holocene beach-ridge strandplains – An example from tropical northeastern Australia" by Brooke, B.P., Huang, Z., Nicholas, W.A., Oliver, T.S.N., Tamura, T., Woodroffe, C.D., Nichol, S.L
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Brooke, Brendan P., Huang, Zhi, Nicholas, William A., Oliver, Thomas S.N., Tamura, Toru, Woodroffe, Colin D., and Nichol, Scott L.
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RELATIVE sea level change , *HOLOCENE Epoch , *SEA level , *CYCLONES , *BEACHES - Abstract
The approach and results of our 2019 paper (Brooke et al., 2019) have been criticised by Dougherty (2022). We examined the sensitivity of a tropical, coarse sand strandplain to changes in relative sea level as expressed through beach-ridge morphology and the elevation of beach berms preserved in the succession of cyclone-generated beach ridges at Cowley Beach, Queensland, Australia. Rather than presenting a new sea-level curve for this region as suggested by Dougherty, our 2019 study of the Cowley Beach strandplain revealed that when compared with the modelled Holocene relative sea-level record and sea-level indicator data for north-eastern Queensland, the strandplain morphology and stratigraphy provide a first-order representation of sea-level position. Importantly, Dougherty (2022) has overlooked the processes involved in the formation of beach ridges at this site and the spatial coverage of our analysis of the strandplain morphology. Both these factors are fundamental to the approach and conclusions of our 2019 paper. We reiterate here that the Cowley Beach strandplain morphology and succession of beach-berm deposits have elevation patterns that match well the broad trend in the regional relative sea-level model for the past 7 ka. We highlight those key beach-ridge formative processes and data limitations neglected in the Dougherty Comment. Finally, we note the challenges and opportunities for further research into the sedimentary records preserved in this distinctive type of tropical strandplain. • First-order changes of sea level can be detected in the Cowley Beach strandplain. • The coarse sandy ridges comprise a berm capped by cyclone-generated surge deposits. • Processes forming these ridges are in marked contrast to temperate strandplains. • There is negligible aeolian deposition contributing to these low-relief ridges. • Uncertainties in ridge elevation, age and GPR data limit sea-level reconstruction. [ABSTRACT FROM AUTHOR]
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- 2022
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