Documenting and Dating Olmec-Style Cave Paintings, Guerrero, Mexico

Caves were central elements of the ancient Mesoamerican cultural landscape, and many people continue to worship at caves even today. This research assesses of the role of west Mexican caves in Formative period religion and politics. The iconic paintings of Oxtotitlán Cave, Guerrero, belong stylistically to Mesoamerica’s first international art style, the Olmec (1300-400 B.C.). Painted figures represent supernatural animals as well as powerful human lords. The Guerrero images constitute early examples of a long tradition of mural painting in Mesoamerica. This project uses precision drawing and advanced technologies in imaging, image processing, chemical analysis, and dating to document these early paintings and their cave context. Imaging technologies included nighttime ultraviolet and daytime infrared digital techniques, as well as standard digital photography. Digital images and video were further processed computationally to reveal nuances and visual elements normally difficult to discern. These photographic images, together with field observations, contributed to accurate artistic renderings of the paintings designed to make the data more accessible to both scholars and the general public. Chemical analysis of pigment composition included X-Ray Fluorescence (XRF) and other sophisticated techniques. The chemical data determine the presence of materials suitable for radiocarbon and calcium oxalate dating. Exposure and tourism are currently endangering the paintings at Oxtotitlán, and this work is essential to their conservation. This “proof of concept” project has provided the basis for future comprehensive recording and dating of the early painted murals in other west Mexican caves such as Juxtlahuaca and Cahuaziziqui.