Implications of anomalous relative sea-level rise for the peopling of Remote Oceania

Abstract

Settlement of Remote Oceania began ~3,500 to 3,300 y ago and coincided with falling sea level across the equatorial Pacific Ocean. Archaeological evidence suggests that people arrived on Pohnpei and Kosrae (high islands in Micronesia) ~1,000 y later than on other high islands. We reconstruct sea level on Pohnpei and Kosrae using mangrove sediment and find that rather than falling, sea level rose by ~4.3 m over the past ~5,700 y because of subsidence. This rise likely submerged coastal evidence for the initial settlement and current estimates of when people arrived are therefore biased young. Our results allow reconsideration of the pathways and interactions between voyaging groups across Remote Oceania, and the interpretation of the Nan Madol and Leluh monuments. Keywords: sea level, Micronesia, mangrove, archaeology, Oceania