REVEALING UNANGAX HISTORY AND RESILIENCE IN THE ISLANDS OF FOUR MOUNTAINS, ALASKA USING GEOCHEMICAL AND GRAIN SIZE ANALYSES

During 2014 and 2015 an interdisciplinary team of researchers and students studied Unangax (Aleut) prehistoric village sites in the Islands of Four Mountains (IFM), eastern Aleutian Islands. Multi-elemental and grain size analyses are used to evaluate sedimentological, volcanological, soil-forming, and anthropogenic processes and to provide a better understanding of stratigraphic sequences at four sites. Sample locations include two stratigraphic profiles on Carlisle Island (AMK-0003 Units 3 and 4), one profile on Chuginadak Island (SAM-0014, West Ravine Profile), and, for comparison, one natural profile on Carlisle. The Carlisle profile consists of 15 layers that temporally correlate with upper layers of AMK-0003 Units 3 and 4. On Carlisle Island, AMK-0003 Unit 3 is ~125 cm deep (maximum age: 3,630-3,720 calibrated yBP, 2sigma, 99.3% probability); AMK-0003 Unit 4 is ~305 cm deep (maximum age: 3,640-3,720 yBP, 2sigma, 99.3% probability). SAM-00014 West Ravine Profile is ~270 cm deep (maximum age 3,690-3,830 calibrated yBP, 2sigma, 99.3% probability). Each archaeological profile intersects multiple cultural layers. Results indicated that both the Carlisle and Chuginadak villages were constructed on alluvial debris fans and periodically accumulated ash and tephra. Abrupt changes in grain size and organic carbon content correlated with volcanic tephra and ash deposition. When compared with the natural stratigraphic sections, archaeological layers showed higher levels of organic carbon, nitrogen, and phosphorous, and in some cases calcium, good indicators of human occupation. Combining these two types of analyses for multiple archeological sites provides a better understanding of the various geological events that might have impacted prehistoric Unangax people in the Islands of Four Mountains.