Characterizing the Construction of Terraced Hills (Cerros de Trincheras) in the Sonoran Desert Through Soil Characterization and Micromorphology

Tumamoc Hill (AZ AA:16:6[ASM]) is the site of a prehistoric hilltop village in Tucson, Arizona. Indigenous people living in the lowland deserts of the southwest U.S. / northwest Mexico built hilltop villages, known as cerros de trincheras, more than 3,000 years ago. AMS ¹⁴C samples from terraces and a community structure in the center of the hill yielded dates consistent with the Late Cienega phase (400 B.C.-A.D. 50) and the Tortolita phase (A.D. 550-650). Soil descriptions and micromorphology analyses identified modified soils on the summit and weakly developed terrace soils that formed after terrace construction, further reinforcing that the earliest village was constructed on Tumamoc's summit during the Late Cienega phase. Given the timing, location, and nature of construction on Tumamoc Hill, we argue that it represents an early form of monumentality that reflects emergent social complexity at the terminus of the Early Agricultural period in the region.