A TWELVE THOUSAND YEAR HISTORY OF OBSIDIAN PROSPECTING IN EASTERN BERINGIA

Since 2006 we have used portable X-ray fluorescence (PXRF) and laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) to analyze approximately 4500 archaeological samples from northwestern North America, specifically Alaska and adjacent parts of Canada. Of the approximately 60 geochemically distinct obsidian groups that have been identified, only about 10 have a confirmed geological source, and a major thrust of our work has been the identification of the geological sources for these "unknown" geochemical groups. In this paper we describe the major obsidian sources for the region, provide a status report on efforts to correlate archaeological specimens to outcrops, and recommend a standardized terminology for source locations and geochemical groups. Key findings include: 1) A small number of obsidian sources were used intensively and the obsidian from them transported widely; the three most commonly used sources (Batza Tena, Okmok, and Wiki Peak) account for 81% of all analyzed samples. 2) Most obsidian sources in Alaska were used lightly and the obsidian from them transported only locally; at least 42 sources are represented by fewer than 10 archaeological samples each. 3) The process of prehistoric obsidian source location was fast and efficient; within a given region (e.g., Central Alaska, Aleutian Islands, Southeast Alaska), prehistoric people identified all of the common obsidian sources and some of the rare sources concurrent with its initial settlement. 4) Contrary to the notion of Beringia as a crossroads of cultures and hub of cultural interaction we have identified very few examples of Russian obsidian in Alaska and there are no known cases of Alaskan obsidian in Russian archaeological collections.