The Holocene Becher Point Cuspate Foreland, Western Australia – An internationally significant and globally unique potential geopark

Abstract

Located in south-western Australia in a distinctive setting sedimentologically, oceanographically, climatically, biologically, and sea-level history context, the Becher Point Cuspate Foreland is globally unique, and is a site of International Geoheritage Significance that has the potential to be developed as a Geopark. The cuspate foreland is part of an extensive shore-parallel Holocene coastal sand system that forms the seaward edge of the Swan Coastal Plain and eastern border of the Rottnest Shelf. It is the largest cuspate foreland complex in Western Australia and one of the largest in the World. Sedimentary accretion in the region began some 7000 years BP with a sea level + 2 m AHD. Since then, attended by a progressive climate change, sea level has steadily fallen to its present position, and sedimentation has built a coastal plain of low beach ridges with wetlands in the swales. Sedimentologically and stratigraphically, the cuspate foreland developed by seagrass bank accretion shoaling to the strand to form beach and beach-ridge/dune deposits capped in the swales by wetland deposits. Key features of the Cuspate Foreland are (1) the accreted Holocene beach-ridge plain, (2) the evolution of Holocene swale wetlands, (3) the Holocene sea level history, (4) Holocene climate history as recorded in the wetlands, and (5) a host of small-scale geological phenomena. The complex of beach ridges and swale wetlands is the basis of a geopark in which coastal plain evolution, wetland evolution, Holocene sea level history, and Holocene climate changes can be explored and explained essentially in an outdoor Museum. To illustrate the richness of the natural history information, from macroscale to microscale, embedded in the Becher Point Cuspate Foreland, we choose, as case studies, two aspects of the area and describe them in a holistic and multi-scalar manner for education and research, and potential thematic geotours.