2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 233-11
Presentation Time: 4:15 PM


DUNN, Richard K., Department of Earth and Environmental Sciences, Norwich University, 158 Harmon Dr., Northfield, VT 05663 and VAN TILBURG, Jo Anne, The Cotsen Institute of Archaeology and Easter Island Statute Project, University of California, Los Angeles, 405 Hilgard Ave, Los Angeles, CA 90024, rdunn@norwich.edu

A record of erosion and deposition coupled with paleobotanical data and age analyses contextualize the nature of land use, the impact on the landscape, and the timing of events at the site of megalithic statue (moai) production on Easter Island. The island has presented a possible case study for human-driven ecological catastrophe, and at the site of maximum and intentional landscape disturbance, the moai quarry, there is evidence for major impact on the landscape, but also for its integrated and multi-activity use. Previously published and new paleobotanical data from our excavations reveal gardening in the basin prior to, during, and after the site was active as a major quarry. Crops present included foodstuffs, e.g., banana, and plants important for materials use, e.g., mahute for rope.

A palm-rich forest dominated before human activity in the quarry basin, but rapid denudation of the landscape occurred as trees were removed and quarries were opened. Age control on erosional and depositional events comes from obsidian hydration and AMS radiocarbon dates and reveals that quarry activity lasted two to three centuries, ca. 1200 AD to 1450 AD, and that this was coupled to erosional dissection of a thick soil profile. Gullying resulted in localized depocenters for quarry-related debris deposits that subsequently were buried by colluvium and have high preservation potential. Stratigraphic, soil micromorphological, and paleobotanical data reveal that cessation of quarry activity led to fairly rapid burial of slopes, including deep burial of upright moai, by discrete pulses of colluvial deposition. Moai were not intentionally buried in a single event. Within two to three centuries, slopes were largely buried and had become relatively stabilized, while horticulture continued within the basin beyond European contact at 1722 AD.