Sea levels, shorelines and settlements on Pacific reef islands.

Abstract

A reassessment is made of the model of Dickinson (2003, Journal of Coastal Research), which proposed that many Pacific island coasts were settled only after the palaeoreef flats or shore platforms that formed during the mid-Holocene sea-level highstand emerged above high-tide level: a point in time known as the crossover date. Focusing on reef (atoll) islands, the analysis suggests that this model has potential when applied to islands east of 178°E, with some, such as Funafuti (Tuvalu) and Atafu (Tokelau), being settled around the time of their crossover dates and others to the east and north-east a few centuries later. The model fails to explain the settlement of atolls in the north-west Pacific (Marshall Islands and eastern Kiribati), where islands formed well before crossover dates, something that can be attributed to the larger tidal range and complex interplay between sea level and reef up growth. The enduring legacy of Dickinson to Pacific archaeology is the demonstration that people were operating in a dynamic environment that presented them with new challenges and opportunities rather than in an environment that was static.