An integrated approach to surveying an Early Agricultural period landscape: Magnetic gradiometry and satellite imagery at La Playa, Sonora, Mexico

La Playa (SON F:10:3) in Sonora, Mexico is the single largest Early Agricultural period (2100 BCE-50 CE) site in the Greater Southwest. Modern erosion is rapidly destroying large portions of the archaeological site, highlighting the urgent need for documentation of threatened archaeological structures and features. An integrated approach to archaeological survey is presented here with particular emphasis on magnetic gradiometry as a tool to efficiently survey and document the complex palimpsest of irrigation canals, agricultural fields, and structures at La Playa. This is an under-utilized method in the identification of prehistoric earthen irrigation canals in the southwest U.S./northwest Mexico region. Magnetic gradiometry detected approximately 3 km of intact irrigation canals, almost 8700 m2 of agricultural fields, and twelve circular structures in areas that had not yet been eroded. Satellite imagery and GPS survey documented the remains of almost 12 km of irrigation canals in eroded areas of the site. This multi-technique methodology successfully documented locations of irrigation canals and associated agricultural features both in eroded areas of the site and areas threatened by erosion. These datasets contribute to a comprehensive spatial reconstruction of the Early Agricultural period landscape and lend insight into landscape organization and a deeper understanding of early irrigation technology.