Paper No. 91-12
Presentation Time: 11:10 AM
THE EFFECT OF HOLOCENE ERUPTIONS ON PREHISTORIC HABITATIONS IN THE ISLANDS OF FOUR MOUNTAINS, ALASKA
Cleveland Volcano, in the Aleutian Islands, is one of the most persistently active U.S. volcanoes of the last 20 years. This investigation has sought to determine how often it and the adjacent volcanoes of the Islands of Four Mountains (IFM) group may have erupted during the prehistoric period of human habitation. This is the first investigation of the eruptive histories of this portion of the Aleutian archipelago. By identifying, dating, and tracing tephra layers across the landscape and in various cultural locations we can (1) correlate the chronological framework of village occupations on different islands and (2) understand how volcanic activity could have impacted people and the ecosystem on local and regional scales. Of the nine volcanic islands that comprise the IFM, Herbert and Carlisle consist of single volcanoes; Chuginadak encompasses two volcanic cones—Tana and Cleveland—and an isthmus marked by four discrete cinder cones. Field evidence, grain size analysis, initial geochemical characterization of selected tephras, and new radiocarbon dates suggest Cleveland was active periodically during the last 9,000 years. Among the tephras, we identified a distinctive and coarse grained tephra (dated as ca. 1.1 cal kBP) at a peat outcrop near prehistoric village site CR-03 on Carlisle Island. We also observed this CR-02 Tephra sandwiched between cultural layers in house pits at the CR-02 village. The dates obtained from charcoal fragments in the cultural deposits are slightly older than peat dates. A cultural layer lies immediately above the CR-02 Tephra. This evidence suggests that prehistoric humans almost immediately returned to their village following this particular eruption.