Age of a charcoal band in fluvial sediments, Keiyasi, Sigatoka Valley, Fiji: possible indicator of a severe drought throughout the Southwest Pacific 4500-5000 years ago

Abstract

A 14C date for a charcoal band near the base of the High (10 m) Terrace in the middle Sigatoka Valley (western Viti Levu Island, Fiji) shows that this terrace accumulated mostly within the past 4-5000 years showing it to be a Holocene rather than a Pleistocene (Last Interglacial) landform as previously thought. The charcoal band also indicates that there was extensive, perhaps catastrophic, burning of forests and perhaps an associated local extirpation/extinction of forest taxa. The notion that humans may have been responsible for the forest burning represented by this charcoal band is rejected on account of its age predating known human arrival by at least one thousand years. Attention is drawn to the contemporaneity of this charcoal band and those found in Bonatoa Bog (southeast Viti Levu Island) and in New Caledonia, some 1300 km southwest of Fiji, suggesting that catastrophic forest burning during this period may have been widespread and a regionwide response to a period of prolonged aridity 4500-5000 years ago, possibly associated with a unusually severe El Nino event.