Chronostratigraphic and Paleoenvironmental Evidence for Marsh Habitats during the Early Pueblo I (A.D. 700–900) Occupation of Ridges Basin,Southwest Colorado,USA

Ridges Basin was home to one of the largest early village communities in the American Southwest. The short‐lived occupation grew rapidly around A.D. 750, construction peaked in the A.D. 780s, but Ridges Basin was depopulated by A.D. 810. Chronostratigraphic, paleoenvironmental, and archaeological investigations indicate that abundant food resources related to intermittent marsh habitats attracted migrants into the basin and aided the growing population. Extreme droughts between A.D. 795 and 809 led to decreased crop yields and marsh desiccation. We attribute the abrupt depopulation of Ridges Basin to declining environmental conditions and societal stresses. We describe the impact of marsh formation on the inhabitants, and explore the wider implications of marshes and reservoirs on the Puebloan landscape. We suggest that early Puebloans positioned their settlements in proximity to natural marshes to take advantage of the abundant plant and animal resources, which later Puebloans achieved through the construction of reservoirs.