Geomorphic and Archaeological Landscapes of the Sigatoka Dune Site, Viti Levu, Fiji: Interdisciplinary Investigations

Abstract

Understanding the geomorphic setting of the Sigatoka dune field on the south coast of Viti Levu in Fiji is critical for interpreting the associated archaeological site, with culture levels dating back to 3000 years ago. The dune field lies along the seaward fringe of the Holocene delta of the Sigatoka River, which drains interior highlands astride the boundary between the wet windward and dry leeward climatic zones of Viti Levu. Sand brought down to the shoreline by the Sigatoka River is transported longshore westward by surf along the delta front and blown inland oblique to the shore by the prevailing trade winds. Three successive culture levels, dating to approximately 900-400 B.C., A.D. 100-400, and A.D. 1300-1500, respectively, occur in three discrete paleosol horizons that are buried near the present beach face under younger dune sand. Our geomorphic analysis of the Sigatoka delta plain arid its environs reveals a complex Holocene history of progradation and aggradation, shifting distributaries, sea-level change, subsidence owing to sediment compaction, and enhancement of dune development through time. The oldest two of the three paleosols that have yielded artifacts evidently formed on a low-lying backbeach coastal flat, located behind a beach-dune berm-crest ridge of low relief, with only the youngest of the three paleosols representing a temporarily stabilized surface within a growing dune field. Enhanced dune growth may have been fostered by augmented sediment delivery to the coast as a result of wholesale inland deforestation associated with population movement into the interior highlands of the Sigatoka drainage basin. KEYWORDS: coastal dunes, deltas, Fiji, geoarchaeology, Lapita, Sigatoka, Viti Levu.