The application of stable carbon isotopes as an enhanced method for statistical crossdating: a case study from Range Creek Canyon, Utah

Dendroarcheological samples pose a particular challenge when attempting to crossdate them against a master chronology. Previous attempts to accurately crossdate dendroarcheological samples from Range Creek Canyon have had limited success (Towner et al. 2009), due in part to the nonsignificance of the master chronology compared to the relatively long period spanning prehistoric occupation, and the limited size of the building materials selected by the Fremont inhabitants. In an attempt to increase the statistical significance of a chronology, and thus increase the success of crossdating dendroarcheological materials, we built two chronologies from a more sensitive species, J. osteosperma (Utah juniper), using both ring width and stable carbon isotopes. The use of a more sensitive species than previous attempts yielded one additional marker year, resulting in a 3.125% increase. The isotope chronology identified an additional three marker years, yielding a 9.375% increase in marker years over ring width alone and a total 12.5% increase when combined into a multivariate chronology, suggesting that including other variables should be a priority for problematic dendroarcheological studies. Using multiple variables in a chronology allows the use of alternative signal matching techniques, e.g. Principal Component Analysis (PCA), to explore several underlying signals rather than just the extremes of one response function. We explored the underlying structure of the two variables using a PCA and report on its potential strength for more advanced crossdating than traditional visual methods. Finally, we provide recommendations for future dendroarchaeological research conducted in Range Creek Canyon.