Aboriginal artefacts on the continental shelf reveal ancient drowned cultural landscapes in northwest Australia

TLDR

Underwater cultural heritage across Australia’s 2 million km² of drowned landscapes requires stronger legislation to protect a vast, largely undiscovered human history. The study establishes research strategies and technologies to locate deeper archaeological sites on Australia’s continental shelf and beyond. The authors identified two sites—Cape Bruguieres (260+ lithic artefacts down to –2.4 m) and Flying Foam Passage (submerged freshwater spring at –14 m)—using an iterative predictive framework that combined aerial and underwater remote sensing with diver surveys across 0–20 m depth, and analyzed artefact context to confirm in‑situ deposition and assess taphonomy. Australia’s first confirmed ancient underwater sites off Murujuga were identified, with radiometric dates indicating submergence by 7000–8500 cal BP, and lithic assemblage comparisons support this chronology.

Abstract

This article reports Australia's first confirmed ancient underwater archaeological sites from the continental shelf, located off the Murujuga coastline in north-western Australia. Details on two underwater sites are reported: Cape Bruguieres, comprising > 260 recorded lithic artefacts at depths down to -2.4 m below sea level, and Flying Foam Passage where the find spot is associated with a submerged freshwater spring at -14 m. The sites were discovered through a purposeful research strategy designed to identify underwater targets, using an iterative process incorporating a variety of aerial and underwater remote sensing techniques and diver investigation within a predictive framework to map the submerged landscape within a depth range of 0-20 m. The condition and context of the lithic artefacts are analysed in order to unravel their depositional and taphonomic history and to corroborate their in situ position on a pre-inundation land surface, taking account of known geomorphological and climatic processes including cyclone activity that could have caused displacement and transportation from adjacent coasts. Geomorphological data and radiometric dates establish the chronological limits of the sites and demonstrate that they cannot be later than 7000 cal BP and 8500 cal BP respectively, based on the dates when they were finally submerged by sea-level rise. Comparison of underwater and onshore lithic assemblages shows differences that are consistent with this chronological interpretation. This article sets a foundation for the research strategies and technologies needed to identify archaeological targets at greater depth on the Australian continental shelf and elsewhere, building on the results presented. Emphasis is also placed on the need for legislation to better protect and manage underwater cultural heritage on the 2 million square kilometres of drowned landscapes that were once available for occupation in Australia, and where a major part of its human history must lie waiting to be discovered.