New tree-ring-radiocarbon dates reveal drought-migration linkage for central Arizona cliff dwelling

Abstract

Uncertain chronologies of archaeological sites outside the geographic area of secure tree-ring dating in the Southwestern U.S. has hindered wider knowledge about climate challenges and migration in the past. Montezuma Castle cliff dwelling in central Arizona is believed to have been founded by migrants sometime between CE 1100–1300, but comparison with dated events at annual to decadal resolution has been impossible. New 14C dates – including nine wiggle-matched tree-ring segments – indicate that the site was founded and reoccupied precisely during two major droughts in the twelfth and thirteenth centuries. The six highest resolution wiggle-matched elements date to cal. CE 1020–1050, 1083–1155, 1094–1159, 1094–1163, 1133–1169, and 1280–1302 (95.4% posterior density). When these dates are modeled with other samples that directly date construction, it is shown that the edifice was erected between 1125 and 1173 with a late phase of renovation occurring between 1280 and 1305. A sensitivity analysis reveals that the inclusion of wiggle-matched tree-ring segments is crucial to achieving this level of precision, and that there is a lower limit for the number and quality of wiggle-matches for the model to retain its fidelity. We suggest that some cultural shifts in the Verde Valley – traditionally attributed to the arrival of northern groups after about 1250 – began up to a century prior to this time, and that cliff dwellings were constructed as an adaptation to insecurities related to climate stress.