Doctoral Dissertation Improvement Award: The Interaction of Long Term Canal Irrigation and Wetland Development

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The archaeological study of traditional Native American agricultural techniques is essential for the evaluation of long-term land use because it allows for the examination of environmental change at the time scales necessary to test for sustainability. The earliest farmers on the floodplains of the Sonoran Desert used careful planning, group cooperation, and experimentation in the massive reconfiguration of the natural environment for agricultural purposes. The diversity in size and complexity of these early farming communities requires examination of the specific factors that favored the significant investment in landscape modification in order to understand the development of these practices. The examination of local environmental conditions and their relationship to the timing of agricultural practices is key in understanding the regional development and demise of early earthen irrigation canals. This information will contribute to the growing body of knowledge of sustainable earthen irrigation systems, an agricultural technology commonly used in arid environments today. Results from this interdisciplinary research have international impacts in earth science, archaeology, and sustainable agriculture. This project supports student training in fieldwork, research, and specialized laboratory techniques for women and underrepresented groups and is a component of a twenty-year collaboration between the University of Arizona and Mexico's Instituto Nacional de Antropología e Historia. This dissertation research will investigate the earliest agricultural technology in the Southwest United States/Northwest Mexico region and evaluate local environmental impacts to determine when and why this technology was developed and subsequently abandoned. Dr. Vance Holliday and Rachel Cajigas from the University of Arizona will use high-precision dating techniques combined with environmental data to determine the timing of early agricultural practices and the relationship to floodplain conditions at the La Playa site in Sonora, Mexico. This site has important implications for the understanding of the development of agricultural techniques because it is the single largest Early Agricultural Period (2100 B.C.-A.D. 50) site in the greater Southwest. Modern erosion is actively destroying large portions of the archaeological site, highlighting the urgent need for study. This research will test the hypothesis that canal irrigation created a wetland environment, eventually leading to unstable depositional conditions. These unstable conditions may have contributed to social reorganization and abandonment of irrigation technology. Radiocarbon and Optically Stimulated Luminescence dating methods will be used to determine the timing of canal use and abandonment. These data will be compared with sedimentological and soils data to characterize floodplain conditions throughout the Early Agricultural period. The results from this study will advance the understanding of early agricultural techniques in arid environments and contribute to a comprehensive chronology of the archaeological site within the greater context of the origins of early agriculture in the Southwest U.S./Northwest Mexico.