Shards in sherds: Identifying production locations and exchange patterns using electron microprobe analysis of volcanic ash temper in northern Rio Grande Biscuit ware

The research presented here focuses on the composition of Biscuit ware ceramics produced during the Classic period (1325-1650 CE) in the northern Rio Grande region of New Mexico. Data from sites in the southern part of the Pajarito Plateau are compared with those from the Chama area to the north to identify production sites. We employ petrographic analysis to determine the composition of lithic inclusions in clay plus electron microprobe chemical analysis of the glass shards in the characteristic volcanic ash temper to identify production location. We combine analysis of temper and paste composition with analysis of mechanical characteristics and design to identify production specialization in specific parts of the region. Examination of Biscuit ware distribution indicates that a specific set of ritual practices in the production area was expressed using a characteristic set of designs and icons. The limited circulation of only larger sizes of Biscuit ware serving bowls to more southerly sites, outside of the production area, likely represents an increase in inter-area communal feasting and the intentional production of goods for use in communal rituals.