Age of the O18 site, Hawai'i

Abstract Seven new [sup.14]C age determinations on short-lived materials yield a sound evidential basis for the chronology of the O18 site on O'ahu Island, Hawai'i, long thought to be an early settlement site. Calibration within a model-based, Bayesian framework indicates that the site was established in AD 1040-1219, some 260-459 years after the current estimate of first settlement, and abandoned in the late eighteenth or early nineteenth centuries. Previously published age determinations are mostly too old, probably due to the 'old wood' effect. O18 appears to be the oldest site on the Waimanalo Plain, but earlier sites in Waimanalo likely exist inland of the plain. Keywords: 018 site, Bayesian calibration, 'old wood' effect, settlement ********** The age of the O18 site has been an important datum in Hawaiian prehistory since the first estimate was published in the pages of this journal nearly 40 years ago (Pearson et al. 1971). Based on an internally inconsistent set of [sup.14]C age determinations, the site was interpreted by its excavators as having been established in the seventh century AD and abandoned by the twelfth century. The estimated date of establishment was subsequently pushed back to the fourth century AD by Kirch (1985), based primarily on volcanic glass hydration dates that are no longer believed to be valid (Tuggle and Spriggs 2001). Kirch considered O18 to be one of only two sites representing the earliest phase of Polynesian settlement of the Hawaiian Islands. This characterization exerted a strong hold on the archaeological imagination. In the early 1980s, it inspired Matthew Spriggs to pull additional samples from storage and have them dated. These samples yielded a stratigraphically inconsistent set of [sup.14]C age determinations that was interpreted more than a decade later with some difficulty by Tuggle and Spriggs (2001) as indicating an occupation span beginning perhaps as early as the eighth century AD and ending in the middle of the fifteenth century AD. Here, we present the results of nine new [sup.14]C age determinations from O18, most of them on short-lived materials. The age determinations on short-lived materials are internally consistent and provide, for the first time, a sound evidential basis for the site's chronology. The [sup.14]C age determinations are interpreted within a model-based, Bayesian framework. An estimate of site establishment yielded by the model-based analysis, supported by the age of an Aleurites moluccana nutshell dated by Spriggs, indicates that O 18 was established several centuries after the islands were first settled by Polynesians. The O18 chronology yielded by the site-specific Bayesian model is extended to include [sup.14]C age determinations from four other sites in the region. The chronologies of all five sites are broadly similar. Like these other sites, O18 was abandoned late in traditional Hawaiian times. The O18 site Site O18 is located on the Waimanalo Plain, at the coast (Fig. 1). It is a small part of a larger traditional Hawaiian settlement pattern in which the coastal plain was used on a regular basis, primarily for activities associated with fishing and shellfishing, by people who kept more established residences inland on the volcanic soils that supported their food gardens. A large portion of the coastal plain was developed as a military installation in the twentieth century, especially during World War II, and much of the traditional Hawaiian deposit was lost during this development. The pattern of sites on the plain today is probably due more to military development than it is to patterns of traditional activity in the past. [FIGURE 1 OMITTED] Immediately inland of Site O18, and at one time probably coterminous with it, is Site 50-80-15-4853, a large expanse of discontinuous cultural deposits on the north bank of Puha Stream that represent primarily cooking and eating activities (Tuggle 1997; Desilets and Dye 2002). …