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.