Stone artifacts in the intertidal zone, Dampier Archipelago: Evidence for a submerged coastal site in Northwest Australia

Abstract

Stone artifacts recently identified in the intertidal zone at Dolphin Island, Dampier Archipelago, suggest Aboriginal Australian occupation before inundation from early to mid-Holocene sea-level rise. If these artifacts do pre-date inundation, they would be the first evidence for a submerged coastal site on the Dampier Archipelago—substantiating persistent Aboriginal use throughout major environmental changes. The find provides supplementary evidence for Early Holocene settlement patterns, site organization and stone artifact production as documented on the outer islands of the Archipelago. It could be argued that the artifacts in the intertidal zone were washed downslope from nearby terrestrial settings where natural stone sources have been quarried. However, chemical analysis of cobbles and artifacts from both the hillslope and intertidal locations indicate that these two source materials are not the same. Furthermore, there is no evidence for reworking: artifact edges are unrounded. The distribution of suitable tool stone across the tidal flats is extensive (as it is elsewhere across this volcanic landscape). Further investigations, including refitting and taphonomic, geomorphological, and sedimentological studies are underway to test the alternative explanations and to provide more detailed context.

Keywords:

• Aboriginal occupation
• mid-Holocene
• sea-level rise
• pXRF
• submerged landscapes

Acknowledgements

We thank Murujuga Aboriginal Corporation’s Circle of Elders and the Murujuga Land and Sea Unit for facilitating this research program in accordance with their cultural protocols and ensuring our safety while working on Dolphin Island. Murujuga: Dynamics of the Dreaming (LP140100393) is funded by the Australian Research Council and partner organization Rio Tinto. Joe Dortch is Project Research Manager; Emma Beckett is a Ph.D. candidate on the Project, Alistair Paterson is a Chief Investigator, and Jo McDonald Lead Chief Investigator. The field team on Dolphin Island included Ken Mulvaney (Partner Investigator), Sarah de Koning (Project Database Manager), Victoria Anderson (UWA Ph.D. candidate), and Rachel Bell and Phil Shiner (Rio Tinto). We thank Annette George (UWA) for undertaking the pXRF analysis and identification of the local lithologies, and Ingrid Ward (UWA); and Mick O’Leary, Jonathan Benjamin, Sean Ulm, and Geoff Bailey, Chief Investigators from the Deep History of Sea Country ARC Discovery Project (DP170100812), for helpful insights.