We investigated the Holocene palaeo-environmental record of the Tuggerah Lake barrier estuary on the south-east coast of Australia to determine the influence of local, regional and global environmental changes on estuary development. Using multi-proxy approaches, we identified significant down-core variation in sediment cores relating to sea-level rise and regional climate change. Following erosion of the antecedent land surface during the post-glacial marine transgression, sediment began to accumulate at the more seaward location at ~8500. years before present, some 1500. years prior to barrier emplacement and ~4000. years earlier than at the landward site. The delay in sediment accumulation at the landward site was a consequence of exposure to wave action prior to barrier emplacement, and due to high river flows of the mid-Holocene post-barrier emplacement. As a consequence of the mid-Holocene reduction in river flows, coupled with a moderate decline in sea-level, the lake experienced major changes in conditions at ~4000. years before present. The entrance channel connecting the lake with the ocean became periodically constricted, producing cyclic alternation between intervals of fluvial- and marine-dominated conditions. Overall, this study provides a detailed, multi-proxy investigation of the physical evolution of Tuggerah Lake with causative environmental processes that have influenced development of the estuary.

Australia, Estuary, Geomorphology, Holocene, Magnetisation, Multi-proxy, Palaeo-environment, Sea-level fluctuation, Sea-level rise, Sediment core, Trace elements
Department of Earth Sciences

Macreadie, P.I. (Peter I.), Rolph, T.C. (Timothy C.), Schroder-Adams, C, Boyd, R. (Ron), & Skilbeck, C.G. (Charles G.). (2015). Holocene record of Tuggerah Lake estuary development on the Australian east coast: Sedimentary responses to sea-level fluctuations and climate variability. GeoResJ, 5, 57–73. doi:10.1016/j.grj.2015.01.002