Sourcing the Megalithic Stones of Nan Madol: an XRF Study of Architectural Basalt Stone from Pohnpei, Federated States of Micronesia

Abstract

Nan Madol is a massive 81 hectare prehistoric administrative and ceremonial complex made up of 93 constructed islets on the high volcanic island of Pohnpei. Built between A.D. 900 and 1650 over earlier settlement remains along the southern coast of Temwen Island within the fringing reef, the site is noted for its distinctive use of columnar basalt and large boulders. XRF analysis presented here suggests the site’s builders favoured columnar basalt from the island’s main shield building stage (7-8 mya) over post-shield material. Boulders incorporated in the architecture are primarily from post-shield stage Temwen Island but supplemented by some main shield boulders from mainland Pohnpei. Preliminary findings further suggest that there were shifts in the relative frequency of quarries used to construct different structures. These shifts could relate to exhaustion of accessible stone from specific sources or perhaps changing preferences for stone from different sources due to social or political imperatives.