A 34 year record of foredune evolution, Dark Point, NSW, Australia

Incipient foredunes are formed by æolian deposition in plants on the backshore. They commonly evolve into established foredunes, and are present on many of the world's coasts, yet there are very few medium to long term studies on how they evolve and change over time. An incipient foredune suite has been monitored at Dark Point, NSW, Australia since 1978, providing a 34 year record of dune evolution and dynamics, and therefore representing one of the very few medium term foredune monitoring sites in the world. The foredune was initiated by the growth of a zone of discrete pioneer plant species (principally Spinifex) on the backshore following the destructive 1974-75 storms. Over a period of 24 years, 5 separate incipient foredunes developed as sediment was gradually returned to the surfzone and beach, and the beach prograded 70m. Sometime after 1998, storms cut back the seawardmost foredune and former foredunes were reactivated landwards of the 1998 foredune. This study demonstrates (i) how incipient foredunes form by both discrete seedling development, and seawards rhizome extension over time, (ii) how ramp and terrace morphologies eventually evolve into ridges, (iii) rates of beach accretion following storm erosion and backshore response, (iv) how wave erosion drives morphological changes and evolutionary sequences on foredunes, (v) the relationships between backshore height, foredune development and sea levels, and (vi) indications for the initiation and evolution of so-called 'beach ridges'.