Recent archaeological studies in Oceania have highlighted the importance of Holocene changes in island landscapes for understanding prehistoric settlement and the cultural adaptations of ancestral Pacific peoples (Anderson 1994, 1995; Dickinson et al. 1994; Gosden and Webb 1994; Hope 1996; Kirch 1996; Kirch and Ellison 1994; Lepofsky et al. 1996; Nunn, 1994a). Some geomorphic changes can be regarded as natural background, unaffected by human culture, others are solely anthropogenic in origin, while still others represent a subtle interplay of both natural and human agency. The complexity of relevant archaeological and geological data dictates an interdisciplinary approach to research. In many Oceanian settings, a full interpretation of landscape and human history is otherwise impossible.
A case in point is the Sigatoka Dune archaeological site on the south coast of the island Viti Levu in Fiji (Fig. 1). The site lies at the eastern end of a parabolic dune field built on deltaic deposits of the Sigatoka River. The dynamic local sedimentary environment, both fluvial and eolian, has resulted in a series of well-stratified, ceramic-rich archaeological deposits that represent the key phases of Fijian prehistory, from first settlement some three millenia ago up to recent times. Over several decades, this important site has attracted a number of archaeological investigations (Anderson et al. 1996; Best 1988; Birks 1973; Birks and Birks 1968; Burley 1997; Crosby 1991; Gifford 1951; Green, 1963b; Hudson 1994; Palmer 1966, 1968). There remain, nevertheless, several questions about site function, periodic abandonment, and subsequent reoccupation that cannot be resolved without a firmer understanding of the surrounding landscape and its evolution.
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The focus of our paper is on the geomorphic evolution of the Sigatoka dune field and its implications for understanding human occupations at the mouth of the Sigatoka River. In offering fresh insights for the Sigatoka Dune site, we emphasize the importance of a combined geological and archaeological approach to Pacific prehistory, and for reconstructions of paleogeography.
SIGATOKA DUNE SITE IN FIJIAN PREHISTORY
Earthenware pottery has been an important portable artifact throughout the Fijian past, and it continues to be made today in selected villages near Sigatoka and elsewhere. Surface exposures of pottery fragments were recorded near the eastern end of the Sigatoka dune field as early as 1944 by anthropologist B. Biggs (Green 1963b). In 1947, E. W. Gifford (1951) undertook archaeological surveys and excavations on Viti Levu, again reporting surface pottery and other materials at two different locations on the seaward slope of the Sigatoka dune field. In the early 1960s, R. C. Green (Green 1963a; Green and Palmer 1963) reconsidered Gifford's material and, analyzing additional ceramic collections recovered in the interim, including one from Sigatoka, developed a chronological framework for Fijian prehistory based on stylistic changes in pottery decoration.
With modification and refinement (Best 1984; Frost 1979; Hunt 1986; Shaw 1967), Green's framework continues to be employed. It includes a four-fold sequence: (1) Sigatoka phase (dentate-stamped and notched ceramics), 1200-100 B.C.; (2) Navatu phase (paddle-impressed relief and leaf-impressed ceramics), 100 B.c. to A.D. 1100; (3) Vuda phase (incised/applique ceramics), A.D. 1100-c. 1800; (4) Ra phase (greater proportion of incised/applique ceramics), c. A.D. 1800-1900. Hunt (1986) has proposed a fifth, transitional phase, Yanuca, between the Sigatoka and Navatu phases. Although we thus summarize the different phases as being defined by relatively discrete diagnostic ceramic types, such is the actual case only for the dentate-stamped ceramics of the Sigatoka phase and the incised ceramics of the later periods. Paddle-impressed relief pottery, first appearing in the Navatu (or Yanuca) phase, continues forward thereafter, albeit with much less frequency in later periods, and there are other ceramic types that transcend chronological boundaries (Best 1984: Fig. …