The evolution of a moderate energy coast in Holocene time, Pacific Harbour, Viti Levu, Fiji

Abstract

In the absence of a fringing reef the Pacific Harbour coast of southern Viti Levu has evolved primarily under the influence of waves generated by the prevailing southeasterly trade winds. By c. 3800 yr B.P., a coastal embayment had been partially enclosed by the formation of a gravel storm beach ridge. Subsequent barrier progradation followed only when longshore sediment was transported into the area from the developing Navua/Deuba Delta to the east, resulting in the accretion of a sandy beach ridge sequence. The estuary/lagoon system enclosed by the barrier was converted into a freshwater swamp in which up to 4 m of peat accumulated.

Evidence indicates that Holocene sea levels in the area are unlikely to have exceeded c. 0.6 m above the present level, which is consistent with most evidence from elsewhere in Viti Levu. However, hydro-isostatic processes may explain the apparent inconsistency between the attainment of modern sea level at c. 4000 yr B.P. in the Pacific Harbour and Labau areas of southern Viti Levu, and prior to 4500 yr B.P. in northern Viti Levu.

Keywords:

• Fiji
• Viti Levu
• Pacific Harbour
• Deuba
• barrier system
• beach ridges
• sea-level
• Holocene
• backbarrier deposits
• coastal evolution
• stratigraphy
• Navua Delta
• paleoenvironment