Collaborative Research: Chronology of Epi-Classic Northwestern Mesoamerica

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The Epi-Classic is one of the most turbulent periods in Mesoamerican prehistory. Primarily due to imprecise chronological control, it is also one of the least understood. With National Science Foundation support, Dr. Paula Turkon (Ithaca College) and Dr. Sturt Manning (Cornell University) will use the "dendrochronology-14C wiggle-match" method to develop a much higher-resolution chronology than previously possible. Though narrowly focused on the northwestern frontier of Mesoamerica, the strong connections between this and other regions will allow this project to advance the dating of prehispanic cultural changes throughout MesoamericaThe most significant northward expansion of the Mesoamerican culture area occurred during the Late Classic to Epi-Classic Period. Theories to explain this mass movement of Mesoamerican peoples and their lifestyles into the north include political disintegration in the Mesoamerican core, climate change in this arid region, and the development of exploitive activities and trade networks. Though our understanding of this region has greatly advanced in recent years, indications of the timing and directionality of cultural influences rely on 14C dates with errors of ± 50-90 years. This project will simultaneously address the chronology issue, and set the stage to examine the climate change theory, by employing the "dendrochronology-14C wiggle-matching" method on existing collections of archaeological wood from Epi-Classic archaeological sites in the Malpaso Valley, one of the northernmost regions on the frontier. The wiggle-match method fits 14C dates from tree-ring segments with a known number of rings onto the 14C calibration curve, producing substantially more precise dates than radiocarbon dating alone. Preliminary work on archaeological wood from the Malpaso Valley demonstrates that even short, less-than-ideal samples, can refine dating precision from a 100 calendar year range to as low as a 16 year range.This project represents the only current attempt to apply dendrochronological work on archaeological wood in Mesoamerica. The development of precisely-dated, tree-ring chronologies for the period that corresponds to the prehispanic occupation of the northwestern frontier will also allow extrapolation of variation in water availability that can, in a future project, set the stage to address the climate change theory as an explanation for the frontier's short-lived occupation relative to other regions of Mesoamerica. This project will provide a forum for Mexican and U.S. archaeologists and dendrochronologists, a venue to train undergraduate students at Ithaca College and Cornell University, as well as provide training opportunities for Mexican students and researchers to explore the application of archaeological dendrochronology in Mesoamerica. Formal presentations by the researchers to discuss the merits of tree-ring dating and project results at workshops and universities in Mexico will both extend the call for suitable materials from existing projects and collections, and encourage the collection of wood/charcoal for tree-ring analysis. The data will be disseminated through peer-reviewed journals, conference presentations, public lectures, and be made available in open-access databases.