The Teewah Transect: GPR-Derived Insights into the Younger Dune Morphosequences on the Great Sandy Coast, Queensland, Australia

Abstract

Gontz, A.; McCallum, A.; Ellerton, D.; Patton, N., and Shulmeister, J., 2020. The Teewah Transect: GPR-Derived Insights into the Younger Dune Morphosequences on the Great Sandy Coast, Queensland, Australia. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 500-504. Coconut Creek (Florida), ISSN 0749-0208. The world's largest sand islands lie off the coast of southeast Queensland, Australia. Between these islands, mainland coastal sand masses, bedrock promontories and rivers exist in low-lying areas. Sediment is sourced from one of the world's longest downdrift systems, transporting sand eroded from sandstones in New South Wales north over 1000 km. Recent work has shown the coastal dune fields have been periodically active for the last million years, at times of high and intermediate sea-levels, and identified a series of aeolian morphosequences that exhibit an onlapping relationship with evidence of significant reworking of more seaward morphosequences to create more landward low-relief aeolian landscapes. In 2012, a campaign that collected over 300 km of ground penetrating radar data was begun to understand the stratigraphic framework of this sand-rich system.. One of the surveys acquired a transect over the dune environment of the southern tip of the Cooloola Sand Mass near the town of Teewah. At this location, the dune field narrows to less than 1.5 km with 20-25 m of relief. The seaward side is characterized by eroding dunes and high bluffs. Moving inland over the highest portion of the dune field, the landscape slopes gently to a near sea level with a pluvial-fluviallacustrine dominated system that drains directly to the Noosa River and the Coral Sea. GPR surveys revealed a complex stratigraphy including primary sediment structures related to aeolian processes overprinted with podzol soil development resulting in post depositional features that range from well-developed soil sequences to incipient horizons. Recent GIS mapping has identified this area as consisting of primarily Holocene systems. The Teewah Transect is presented as a case study demonstrating a spatial relationship of the morphosequences and examines the aeolian-soil relationships at the far southern tip of the Cooloola Sand Mass.