Testing versions of the Bruun rule for low energy macro-tidal tropical beaches against a theoretical late Holocene sea-level high-stand and beach ridge evidence of late Holocene beach faces

Abstract

Kerans, A.J., and Cartwright, N., 2016. Testing versions of the Bruun rule for low energy macro-tidal tropical beaches against a theoretical late Holocene sea-level high-stand and beach ridge evidence of late Holocene beach faces. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 740–744. Coconut Creek (Florida), ISSN 0749-0208.

Significant evidence of late Holocene beach faces is presented in beach ridges along the North Queensland coast between Mackay and the Daintree region. The ages of these ridges has in some cases been dated giving confidence that the rearmost ridges are the result of a combination of cyclone activity and a late Holocene sea level high-stand. The height of this high-stand is the subject of debate, however the level may be confidently predicted through careful and extensive measurement of relict oyster beds in the region. Using pre-existing beach ridge research together with existing and new measurements of oyster beds on Magnetic Island, North Queensland a value for the late Holocene sea level high-stand is proposed which can be compared to the position of the coast on certain beaches during this period. These measurements are a good basis to test the applicability of the Bruun rules and some proposed modifications for the low energy beach systems of tropical North Queensland. This paper firstly examined the late Holocene sea level evidence stored in relict oyster beds and from that proposes a sea level to be used in the analysis. This sea level is then used to test the Bruun rule and variants and examine the differences between dated Holocene beach faces and the recession predicted by these models.