Tongan and Samoan volcanic glass: pXRF analysis and implications for constructs of ancestral Polynesian society

A provenance study of volcanic glass specimens from 12 archaeological sites in the Kingdom of Tonga is carried out employing pXRF (portable X-ray fluorescence) analysis. To accomplish this, volcanic glass samples from previously identified sources in northern Tonga and the adjacent islands of Samoa are analyzed. Results indicate inter-island voyaging and interaction over a 600 km linear distance along the Tongan island chain from first Lapita settlement ca 2900 BP throughout later prehistory. Tongan volcanic glass, however, is not found in Samoa and, with the exception of one late prehistoric specimen, Samoan volcanic glass is not present in Tonga. This distribution challenges current concepts of an integrated ancestral society and homeland common to Tonga and Samoa from the Lapita period onward.

► Source samples for volcanic glass in Samoa and Tonga are reviewed and geochemical characterization is carried out using pXRF analysis.
► Fifty-one archaeological volcanic glass specimens from Tonga are analyzed using pXRF and matched to Tongan or Samoan sources.
► All but one Tongan sample comes from a northern Tongan source, the exception being a late prehistoric Samoan sample.
► Volcanic glass distributions question the extent of interaction between Tonga and Samoa until later prehistory.