Human-use of Rhyolite in Prehistoric Alaska

Fine grained volcanic rocks are common in lithic assemblages of interior Alaska and are amenable to geochemical characterization using a variety of analytical techniques. This study has focused solely on rhyolite with the intent of identifying and delineating geochemical groups that may correlate to specific geological source areas (i.e. the geologic source of the material). pXRF technology is used to analyze, thus far, over 1300 rhyolitic artifacts from over 150 sites in interior Alaska. This project is still on going but preliminary results recognize ten distinct geochemical groups that appear to correlate with distinct geological sources. While geological origins of eight of the ten groups identified remain unknown, two geological sources have been tentatively pinpointed, one (represented by Group H) is located in the central Alaska Range and the second (Group G) in the Talkeetna Mountains. The provisional framework of geochemical variation among tool quality rhyolite in this region is an important first step toward a more robust understanding of lithic technological organization and prehistoric landuse in interior Alaska. 

Project References

Paper title:»Coffman, S. and J.T. Rasic (2015) "Rhyolite Characterization and Distribution in Central Alaska". Journal of Archaeological Science, vol. 57.

Poster title: Eastern Beringian Rhyolite Sourcing, by S. Coffman and J.T. Rasic.» Paleoamerican Odyssey Conference,» Santa Fe, NM. October 2013.

Poster title: Rhyolite Sourcing in Central Alaska – Preliminary Results, by S. Coffman and J.T. Rasic.» 40 ^th »Annual Meeting of the Alaska Anthropological Association,» Anchorage, AK. » March 2013.