This study obtained calendar dates by radiocarbon accelerator mass spectrometry (14C AMS) dating sequential tree-rings of wooden support posts from the buried remains of traditional Kitkahahki Pawnee earthlodges preserved at an archaeological site on the Central Great Plains, USA. The tree-ring segments from the site were dendrochronologically analyzed prior to this study, but the cross-matched site chronology could not be definitively cross-dated and was thus “floating” in time. Our study represents the first floating tree-ring chronology from the Great Plains to be anchored in time by means of independent radiocarbon analysis. Three specimens were analyzed and dated to 1724–1774 CE (82.0% probability), 1774–1794 CE (95.4% probability), and 1800–1820 CE (95.4% probability). These dates correspond to the hypothetical timing of Kitkahahki ethnogensis, the main phase of village growth in the area, and a later reoccupation during a turbulent period in regional history. The results of this study conform to a scenario in which chaotic social conditions correspond to an increase in residential mobility between the core of Pawnee territory and a southern frontier in the Republican River valley.

Age disparities between charcoal samples and their context are a well-known problem in archaeological chronometry, and even small offsets could affect the accuracy of high-precision wiggle-matched dates. In many cases of taphonomic or anthropogenic loss of the outermost rings, sapwood-based methods for estimating cutting dates are not always applicable, especially with charcoal. In these instances, wiggle-matched terminus post quem (TPQ) dates are often reconciled with subjective or ad hoc approaches. This study examines the distribution of age disparities caused by ring loss and other factors in a large dendroarchaeological dataset. Probability density functions describing the random distribution of age disparities are then fit to the empirical distributions. These functions are tested on an actual wiggle-matched non-cutting date from the literature to evaluate accuracy in a single case. Simulations are then presented to demonstrate how an age offset function can be applied in OxCal outlier models to yield accurate dating in archaeological sequences with short intervals between dated episodes, even if all samples are non-cutting dates.

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In the Northern Rio Grande region of New Mexico, USA, Ancestral Pueblo villages experienced rapid demographic and economic growth in the late 14th and 15th centuries A.D. Recent research has proposed that this growth was underwritten by cotton production for exchange. Gravel mulch was an important component of cotton agriculture, but its function and soil legacies are not well understood. Since water management was likely a critical feature of gravel mulch, this study examines soil variables affected by changes to water supply. Gravel mulch analyzed in this study was found to have a substantial impact on the surface soil particle size distribution, but other aspects of soil quality were unaffected. The depth profiles of base cation ratios in mulched and unmodified locations suggest that gravel mulch continues to enhance water infiltration. Based on the timing of cotton development and inferred infiltration depths associated with gravel mulch soils, gravel mulch technology is well suited to the monsoonal precipitation regime of the region and the phenology of cotton.