Soils telling time: Integrating geoarchaeology, experimental archaeology, and Bayesian modeling to refine dating cultural deposits

Abstract

This study combines archaeological soil micromorphology, experimental archaeology, and Bayesian chronological modeling to refine the timing of a pit fill sequence at a 13-14th century CE Ancestral Native American village. Framed within an event-based archaeological perspective, the analysis focuses on identifying discrete phases of deposition, surface exposure, and burial of an intermediary fill zone within a stratified pit feature. Microstratigraphic, pedogenic, and taphonomic observations from this fill zone are compared to soils from 25-year-old experimental features, providing an independent basis for evaluating the temporal implications of archaeological observations. These comparisons support the interpretation that the pit remained open for at least one season and possibly several years prior to infilling. This inferred depositional hiatus is incorporated as a temporal interval within a Bayesian model of radiocarbon dates from the pit, which aids in constraining pit filling to cal. CE 1280–1305 (68.3 % HPD), a substantial refinement over a model based solely on stratigraphic ordering ( cal. CE 1275–1385 , 68.3 % HPD). By structuring chronological analysis around explicitly defined formation processes and their temporal implications, this case study demonstrates how micro-scale geoarchaeological evidence and experimental analogs can be integrated into Bayesian frameworks to improve temporal precision and support event-focused interpretations of archaeological deposits.