Challenges in the Identification of Fresh Volcanic Glass Shards in Ancient Maya Pottery Sherds

Summary

This is an abstract from the "Ceramics and Archaeological Sciences" session, at the 88th annual meeting of the Society for American Archaeology.

The major components of ceramics consist of clay and temper. It is assumed that these components are local. The Maya lowlands are dominated by limestone, and its use as temper is ubiquitous. Therefore, the distinct presence of fresh volcanic ash in the Late Classic period pottery is noteworthy. Efforts to identify a local volcanic source closer than 300 km away have failed. In the course of our inquiry, we have made important discoveries. We had assumed that we could type the ash based on a suite of major and minor minerals, as the glass had experienced the greatest heat exposure in the eruption. While our first assessments showed distinctions, later investigation of time/temperature firing gradients demonstrated that there was alteration in the context of firing. Experiments focused on high silica ash that matched the archaeological samples include the rhyolitic California Bishop Tuff and the Ipopango TBJ. Our report here is of the changes consistent with time and temperature firing experiments. Silica (Si) proves a stable element, while others, especially Sodium (Na) and Calcium, are volatile. We identify consistent changes and argue for caution when evaluating volcanic components of pottery; the process of firing is metamorphic.

This Resource is Part of the Following Collections

• Ceramics and Archaeological Sciences   •
• Society for American Archaeology 88th Annual Meeting, Portland, OR (2023)

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Record Identifiers

Abstract Id(s): 35598.0