Analysis was performed on a 31-artifact sample of Late Terminal Formative obsidian excavated in 2003 from the archaeological site of Yugüe in the Lower Verde Valley of Oaxaca. This analysis was performed to determine the geochemical sources of the individual obsidian artifacts and replicate a prior study of Yugüe obsidian performed by David T. Williams for his thesis at the University of Colorado. This earlier analysis determined that five obsidian sources were present. Sourcing was accomplished using a handheld X-Ray fluorescence instrument and bivariate plotting of relevant trace elements. Five sources of obsidian were found during analysis: Pachuca, Otumba, Paredon, Guadalupe Victoria, and Zaragoza. Williams identified additional sources that were not identified in this study, but he also may have sampled artifacts from the site from other excavations. This previous analysis by Williams also did not attribute sources to individual artifacts, making it impossible for archaeological conclusions to be drawn about the life histories of particular artifacts. By attributing sources to individual artifacts during analysis, this project provides valuable context about both the site of Yugüe during the Terminal Formative period and the lower Rio Verde Valley.

This research project analyzes 5 middens from the Lower Rio Verde valley sites of Río Viejo and Yugüe, Oaxaca, Mexico, during the Terminal Formative period (150 BC to AD 250). The middens are analyzed to further our understanding of socio-political events in public spaces at both sites during this time. The study suggests a greater distinction in use of public spaces between the two sites than within Río Viejo. Frameworks established by Dietler and Hayden for the analysis of feasts do not seem to apply well to the middens analyzed here. Although I argue that evidence from Rio Viejo's middens does not dispute the viability of previous arguments regarding Terminal Formative Río Viejo ritual authorities', potentially elites, efforts to create regional-scale political affiliations, the level to which middens at Río Viejo are evidence of “scaled-up” versions of local practices at outlying sites is inconclusive. Though there is potential for larger feasts at Río Viejo, taken alone the Yugüe midden appears larger. The Río Viejo middens demonstrate greater likelihood for the diminished conspicuousness of status differentiation during the associated events.