PETROGRAPHIC ANALYSIS OF NATIVE AMERICAN CERAMICS IN THE JAMES RIVER BASIN

Geologists have long used the technique of observing thin sections under a petrographic microscope to determine the mineral content of rocks. However, archaeologists have only recently begun to apply these methods to determine the mineral composition of prehistoric ceramics. Quantifying the proportions of minerals, such as quartz and feldspar, both as temper (human additives), and as accidental inclusions (e.g., sand) in ceramic sherds can lead to conclusions about their provenance and transport. A ceramic’s provenance is simply where it was produced, and its transport commonly results from trade. The change in lithology from the Piedmont to the Coastal Plain provinces of Virginia provides an excellent template for discovering patterns among the ceramics of two different Native American groups who resided in the James River basin, the Piedmont Monacans and the Coastal Plain Powhatans. These societies typically utilized their immediate surroundings to find substances to include as temper. Thus one would expect the ceramics created in the Piedmont to contain igneous and metamorphic minerals, including feldspars which weather out by the time the James reached the Coastal Plain. Departures from the expected petrographic signatures of locally produced pottery may provide evidence of trade relations between the Monacans and the Powhatans. To address this question, a sample of forty potsherds from four sites (two Monacan and two Powhatan) evenly spaced along the James were chosen for analysis. Preliminary results suggest that much of the pottery is locally made, as there is a significantly greater amount of feldspar in Piedmont ceramics compared to those of the Coastal Plain (t=2.068, df=38, p=.023). However, one of the coastal sites exhibits particularly high percentages of feldspar, suggesting trade. There are also other site-by-site differences in the proportions of sand and temper relative to matrix. These differences may have cultural significance in terms of both trade and social interaction between the Monacans and Powhatans. Future work entails comparing qualitative observations in hand sample to the quantitative results discovered in the thin sections, as well as quantifying the distance of transport through the James River based on the roundness of individual sand inclusions.