Holocene evolution of a barrier-spit complex and the interaction of tidal and wave processes, Inskip Peninsula, SE Queensland, Australia

Abstract

This paper presents a reconstruction of the Holocene evolution of the Inskip Peninsula in SE Queensland. The peninsula links two major dune fields, the Cooloola Sand Mass to the south and K’gari (Fraser Island) to the north. Geomorphic features of this peninsula include remnant parabolic dunes, numerous beach ridges with foredunes, and a series of spits. Together these features provide insight into Holocene coastal evolution and changing marine conditions. A remnant beach ridge/foredune complex at the northern portion of Inskip may have been connected to K’gari and a river/tidal channel near Rainbow Beach township which separated it from the Cooloola Sand Mass to the south. This channel avulsed northward in the early mid-Holocene (after 8.8 ka) with spit development from the south. This was followed by a phase of beach-ridge/foredune complex development that started by ~6.7 ka. Stratigraphic evidence from the highest and best developed parabolic dunes in the northern portion of Inskip Peninsula indicates dune development from the mid-Holocene beach complex by 4.8 ka. Beach ridges with foredunes continued to prograde but notably declined in size during the late-Holocene. In the latest Holocene (<4.8 ka) many of the late-Holocene beach ridges/foredune complexes have been truncated by a re-orientation of the shoreline and longshore sediment transport has promoted the growth of the modern spit at the northern end of the peninsula. Erosive and longshore processes continue to be highly active because of tidal interactions between Great Sandy Strait and the Coral Sea. This detailed study of Inskip Peninsula’s evolution aids significantly in future coastal management decisions, and provides evidence for World Heritage Area extension for the Cooloola Sand Mass, including the incorporation of Inskip Peninsula itself. It also contributes to the global understanding to coastal evolution in an area of strong wave and tidal interaction.