Regional Clay Sampling

Angela Huster

This summer, I spent a week taking twenty-eight clay samples from across the Toluca Valley and immediately adjacent areas for INAA analysis. Don Cato, one of our local crew members from the excavation, helped by driving in incredibly convoluted loops around the area, and patiently explaining to  bystanders about what I was doing.

I kept crossing the construction route of another major water line to supply Mexico City. Occasionally, it was useful, such as here, where I needed a sample from below substantial modern fill.

These samples should help us identify where our previously sourced archaeological ceramics were made. Because there are only three other sites in the region with sourced ceramics, we have several chemical clusters in our archaeological ceramics that probably represent particular subregions, but we don't know where on the physical landscape those subregions are. More specifically, the new clay samples should help with three specific questions:

What chemical elements are the most geographically variable across the Toluca Valley and therefore the most useful for identifying source areas within the region?

Are the areas immediately to the south and west of the Toluca Valley likely sources for several of our "probably non-local" groups?

Are clays from the west (Toluca Valley) side of the mountain range between the Basin of Mexico and the Toluca Valley similar enough to Basin clays that they could explain some of our groups of Aztec-style ceramics that don't quite match local the very large existing reference data set for the Basin of Mexico?

Soil color and texture recording