Raised Field Agriculture on the North Coast of Peru: Environmental Investigations in the Casma Valley

The Casma Valley, located on the central-northern coast of Peru, is home to a system of raised agricultural fields unique to the region. Relicts of pre-Hispanic culture, these fields are unusually well-preserved and primarily unaffected by modern agriculture. Multiscalar investigations of the Casma Valley raised fields revealed distinct anthropogenic soil alteration and landscape modification patterns. This dissertation assesses why Late Chimú (1300-1470 CE) societies in the Casma Valley converted ca. 2 km2 of land into raised agricultural field systems. This project is designed to investigate the composition and operation of raised fields, the short and long-term effects of field operation, the field layout, the motivations behind field creation, and the cultural associations and chronology of the fields. These topics are addressed through field excavations, soil coring, downhole magnetic susceptibility, soil and plant material testing, drone survey, flow modeling, and thermal imagery. The archaeological and environmental evidence indicates the clear presence of past raised fields, with many conditions reminiscent of similar systems and some conditions unique to this location. Results suggest that these raised fields may have been cultivated earlier than believed, and more recent revitalization attempts were made. Field conditions indicate that while crop growth could have been sustained for some time, there were long-term and likely unintended consequences, including extreme salinization and poor drainage. Soil and plant testing improved our understanding of soil fertility, crop growth, and the persistence of certain soil properties. Finally, hydrologic and temperature analyses help us to understand how water travels to and from the raised field system and the significant disparity in water flow and temperature dynamics within different sub-regions of the fields