Recent Research in Baja California Sur, Mexico

Justin Hyland

One of the most intriguing of these developments occurred in the Sierra de San Francisco located in the midriff region of the peninsula. Here, and in the Sierra de Guadeloupe to the south, there appeared a monumental painted mural tradition among the prehistoric hunter-gatherer groups in the region bearing little relation to the predominately abstract traditions further north and south. The representational imagery, in terms of scale among the world's largest prehistoric painted rock art, is found in literally hundreds of canyon rock shelters and principally depicts human and animal figures painted in red, black, white, and yellow. In recognition of this tremendous cultural legacy, in December 1993 the Sierra de San Francisco was named to the UNESCO World Heritage List.

In the fall of 1992 Justin Hyland of the Department of Anthropology, University of California, Berkeley and his colleague, María de la Luz Gutiérrez of the Instituto Nacional de Antropología e Historia, commenced fieldwork in the Sierra de San Francisco. Their project, named the Proyecto Arte Rupestre Baja California Sur, is a major two-year program of investigation and conservation and is one of twelve special archaeological projects inaugurated by President Carlos Salinas de Gortari. It is the largest archaeological project ever to take place in Baja California and the largest ever in Mexico to deal specifically with hunter-gatherer archaeology.

Using regional ethnohistory as one source of models, one of the primary objectives is to determine the temporal and functional position of mural sites in the overall prehistoric settlement pattern. Of particular interest is the relationship between the production of imagery and gatherer-hunter social complexity, including the intensification of shamanic institutions and the transformation of gendered relations.

The following are some of the project's major fieldwork accomplishments and areas of continuing analysis:

• Primary fieldwork activities involved surface survey and site excavation. Systematic survey was carried out in four zones, essentially providing an east-west transect from the Gulf of California over the Sierra to the Vizcaino Desert. Over 700 archaeological manifestations were recorded, ranging from ephemeral lithic scatters to large village sites with circular stone structures. Examples of each site type were excavated including the three major mural sites of Cueva Pintada, Cueva Soledad, and Cuesta Blanca 27. In these latter the extremely dry deposits yielded well-preserved textiles and groundstone and flaked stone artifacts with pigment and paint residues.
  
• In November 1992 a major new obsidian source, named Valle del Azufre, was discovered in the Tres Virgines volcanic field to the east of the Sierra de San Francisco. M. Steven Shackley of the Phoebe Apperson Hearst Museum of Anthropology, an expert in obsidian studies in the Southwest and northwest Mexico, was invited to carry out the chemical characterization of the new source. X-ray fluorescence analysis of the obsidian artifacts collected during fieldwork (supported in part by a Stahl grant) has overwhelmingly confirmed that Valle del Azufre was the source for the archaeological obsidian in the area. This is clearly the largest source in Baja California and, with numerous large extraction pits, one of the most intensively utilized obsidian sources outside of Mesoamerica.

Among the obsidian artifacts traced to the Valle del Azufre source is a fluted Clovis-type point from Rancho San Joaquin that the Project identified within a local collection. While a fluted point was reported in the 1940s, also from Rancho San Juan, this is the first Clovis-type point found in Baja California and suggests the presence of a locally focused Paleoindian population.

Given the quantity of archaeological obsidian found in the area, a hydration chronology could be very useful in dating archaeological manifestations at both an inter- and intrasite level. We are investigating the potential for developing a regional obsidian hydration chronology.

• In addition to conventional dating means, we have initiated a major program of direct radiocarbon dating and composition analysis of prehistoric paint samples from the mural sites. This research is being carried out in collaboration with Erle Nelson of Simon Fraser University in Canada and the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory.
  
• Sampling was conducted at three mural sites in Arroyo San Pablo and at four sites in Arroyo San Gregorio. In addition to taking samples from the murals themselves, more than a dozen metates and numerous basalt flakes with pigment and paint residues were discovered on the surface and from excavated levels at the tested mural sites. Apart from providing a source of pigment and paint samples that reduces the need for destructive sampling of the murals, these finds are providing important information regarding the techniques involved in paint preparation and application. Composition analyses being carried out in preparation for eventual dating indicate that the pigments are iron and manganese oxides and that there is sufficient carbon in the samples for AMS dating.
  
• An integral part of the analysis of regional mobility and settlement in the Sierra involves the integration of field data into a Geographic Information System (GIS). As tourism to the Sierra is expected to increase substantially with the UNESCO designation, the system is being designed so that it can subsequently form the basis for monitoring tourist and other impacts as part of an overall site management plan for the Sierra.

With fieldwork completed, the project is engaged now with data analysis and dissemination of results. Papers were given at the 1994 Society for American Archaeology meetings and at the 1994 International Rock Art Conference in Flagstaff, AZ. In addition to journal publications in Spanish and English, a final project monograph will be published by the Instituto Nacional de Antropología e Historia.

The project has been supported by Fondo Nacional Arqueológico, the Fulbright-García Robles Program, and the Wenner-Gren Foundation for Anthropological Research. We also wish to acknowledge the indispensable and full participation, both practical and theoretical, of the local Californios in the Sierra without whose help and knowledge this work could not have been carried out. In addition, we were enthusiastically assisted in the field, often in far less than ideal conditions, by students from the Mexican Escuela Nacional de Antropología e Historia, the Universidad Complutense in Madrid, Spain, the University of California, Berkeley, and California State University Chico.