Historical ecology has provided the field of geoarchaeology in Oceania with the concept of an island landscape as a historical product, invented from the dynamic interactions between natural processes and human agency. Since Davidson's work in Nukuoro (1971) and Dye's introduction to the prehistory of Majuro in the Marshall Islands (1987), systematic excavations of atoll islets have also been based on this tenet. Following this concept, this study presents a geoarchaeological examination of the long-term history of the pit- agricultural landscape in Laura Islet of Majuro Atoll, which now consists of 195 pits showing remarkable undulation and anthropogenic vegetation on their spoil banks. Our excavations, conducted since 2003, have revealed that human habitation on Laura began as early as 2,000 years ago, soon after the emergence of the core islet, which probably followed a relative drop in sea level in the late Holocene. Some centuries later, the inhabitants started excavating agricultural pits for the cultivation of wet taro, probably Cyrtosperma spp. The subsequent sea-level decline would have enlarged the foraminiferal sediment; the islet then extended its landform both oceanward and lagoonward as well as along the longitudinal axis stretching north to south. The land accretion caused its inhabitants to increasingly extend their activity space and readjust areas for habitation. It would also have enlarged the volume of the freshwater lens, prompting additional construction of agricultural pits even in the area just behind the lagoon- side beach ridge. Most of the current landscape was formed by around 1,000 years ago at the latest. Geoarchaeological synthesis of Pacific atolls will enable the precise elucidation of local chronological relationships between land accretion and expansion of human activities.
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