New excavations in Easter Island's statue quarry: Soil fertility, site formation and chronology

摘要

This study centers on excavations in the inner region of Rano Raraku, the megalithic statue (moat) quarry of Rapa Nui (Easter Island). In Rano Raraku a transformed landscape is reconstructed based upon soil chemistry, micromorphology, and macro and micro-botanical data framed within a stratigraphic and radiocarbon informed Bayesian model that is the first for Rapa Nui. We focus on moat RR-0001-156, one of only three moai in the island-wide corpus known to be embellished with a dense suite of cohesive petroglyph motifs. Our results confirm a cultivated landscape present on the inner south and east slopes of Rano Raraku that included sweet potato and probably bottle gourd along with Polynesian transfers banana, taro, and paper mulberry from the 14th century AD continuing into the early 19th century AD. During this time of sociopolitical transformation and land use change across the island labor-intensive rock gardens were developed to increase productivity as soil fertility declined in the context of deforestation and perhaps drought while the pan-island center of 'Oroqo (Orongo) emerged at Rano Kau with an intensive ritual focus on fertility. Rano Raraku in sharp contrast had (and still has) extremely fertile soils that are the weathering byproduct of lapilli tuff sediments generated from the quarrying process and localized human activity. This study validates Rano Raraku as the major moat production center, establishes chronological parameters for the unique embellished statue and describes agricultural fertility to hypothesize a rich, multi-use landscape for Rano Raraku inner region that is unparalleled elsewhere on Rapa Nui.