Technological Decision Making: Fused Shale Tool Production in California

Abstract

Close examination of lithic raw material characteristics in conjunction with regional and diachronic artifact analyses is essential to our understanding of human technological decision making. I explore technological features and performance characteristics of a major lithic raw material type, fused shale, used by Chumash and Tongva toolmakers of southern California for making spear and arrow points. The primary source for this material was the Grimes Canyon vicinity, 35 km inland from Ventura, California. Fused shale was one of several cryptocrystalline materials favored regionally for making projectile points, along with various cherts from the Monterey and Franciscan formations and, more rarely, non-local obsidians. I discuss physical characteristics of fused shale, the chronological and spatial distribution of fused shale artifacts, the propensity of fused shale points to fracture, and results of a preliminary portable X-ray fluorescence (pXRF) trace elemental analysis on source material from the Grimes Canyon quarry as well as archaeological specimens from Middle through Historic period components at northern Channel Islands sites.