Blade Running: Middle Preclassic Obsidian Exchange and the Introduction of Prismatic Blades at La Blanca, Guatemala

Abstract

Obsidian prismatic blades first appeared in the Pacific coast of Guatemala at the beginning of the Middle Preclassic, ca. 900 b.c., at the site of La Blanca. Blades were imported in finished form and supplemented an existing technology based on hard-hammer percussion. This indicates that by the Middle Preclassic obsidian was being traded in at least two forms: raw material and finished products. The beginnings of blade use coincide with a number of important social and political changes on the Pacific coast. Most important of these are the emergence of La Blanca as a regional center and the formation of a settlement hierarchy that includes over 50 sites. X-ray fluorescence reveals that the material used to make the blades comes from three geological sources: El Chayal, Ixtepeque, and San Martín Jilotepque. An analysis of the source frequencies through time reveals that El Chayal obsidian dominates the assemblage throughout the Conchas phase, with Ixtepeque being a minor source in all subphases. San Martín Jilotepeque obsidian is absent in the Conchas A and B subphases, but is present in Conchas C and D. This latter occurrence may signal a shift in trade relationships, but the overall pattern suggests that exchange connections established in the Early Preclassic were continued during the Middle Preclassic.