Obsidian distribution and exchange in the north-central frontier of Mesoamerica.

Abstract

This study examines issues of intercultural interaction and frontier development through an analysis of obsidian acquisition, distribution, and exchange in the region defined as the north-central Mesoamerican frontier. Fieldwork to locate sources and obtain obsidian artifact samples is presented and neutron activation analysis is used in the compositional study of up to 16 obsidian sources in six source areas and a total of 167 artifact specimens. These data are integrated with results from previous compositional studies to reconstruct distribution patterns related to eight northern frontier areas: the Tlaltenango Valley, the Bolanos Valley, the Juchipila Valley, the Malpaso Valley, the Chalchihuites Culture Area, the Loma San Gabriel Culture Area, and the site of Casas Grandes. Results of the analysis indicate two distinct systems of obsidian distribution. First, local consumption of obsidian obtained from nearby sources in the Sierra Madre Occidental. Second, long distance exchange of prismatic blades to sites in the north from workshops in the Mesoamerican core. The former pattern appears to have emerged early, during the Archaic, and remained with some modification over time. This included in some instances, partitioning of shared source areas by neighboring populations, perhaps as a response to increased sedentism and territoriality. Blade exchange appears in the eighth century and continues into the Postclassic period. With the exception of Casas Grandes where none have been found, prismatic blades appear only at sites exhibiting formal, ceremonial architecture and are associated with increasing participation by frontier societies in Mesoamerican ritual such as bloodletting and mortuary processing and display of human bone. This study concludes that economic and political underdevelopment of peripheries implicit in many core-periphery models does not apply to the north-central Mesoamerican frontier. Instead, local elites dominate extra-regional contacts while local economy remained independent and largely unaffected by core resources or administration. As a result, importation of prismatic blades, when it occurs, had little effect on local economy and obsidian procurement. Ideologically, however, the effects may have been more pervasive. Elites, as the primary conduit for interaction with the Mesoamerican core, could control the adoption of core ideologies. This had a significant impact on local socio-political process, economy, and cultural evolution in the northern Mesoamerican frontier.