Andean Clays


The pre-Hispanic states of Andean South America are famous for their polychrome ceramics. They are recovered during archaeological excavations of burials, houses, palaces and temples. Ceramic vessels were used for many functions, including cooking, storage and in ritual events. In order to understand not only what ceramic vessels were used for but also how they were made, Field Museum scientists have been examining pottery production in the ancient Andes by investigating where people procured the raw clays used to make ceramic vessels.

By working closely with modern potters, Peruvian geologists, and conducting field surveys, Field Museum scientists are identifying numerous clay deposits in several valleys in Peru and Chile; thus, far comprehensive collections from the Azapa (Chile), Moquegua (Peru) and Vilcabamba (Peru) valleys have been made.  Pilot collections have been made in most coastal valleys from Lima to Moquegua. Samples of these clays were brought to the Chicago and analyzed in the Field Museum using LA-ICP-MS to determine their chemical composition. This composition is then compared with archaeological ceramics to identify which clays were used by ancient potters.

The first clay study was undertaken in the Moquegua Valley, located in southern Peru. The valley is particularly important because it was the only known location where the early Andean states, the Tiwanaku and the Wari established colonies at the same time (AD 600-1000). Survey and analysis demonstrated that there are five different types of clay that can be distinguished by their chemical composition. When these clays were compared with Tiwanaku and Wari ceramic sherds from the Moquegua Valley, it was evident that potters from the two colonies only used clays that were available in their colony’s respective territories.

In a second clay study, scientists collected clays from the Cuzco region, heartland of the Inca Empire. The chemical composition of these clays was compared with Inca and pre-Inca ceramic vessels that are part of the Field Museum’s permanent collections. Some of these vessels were acquired over one hundred years ago. Although they were known to be from the Cuzco region, there was limited provenance information, and by linking them with local clays, this analysis is providing more specific data on exactly where in the region they came from.

Photo: Clay outcrop in the upper Moquegua Valley, Peru, courtesy of Nicola Sharratt.