Human and ecological responses to the Northern White River Ash eruption

Abstract

The White River Ash northern lobe (WRAn) volcanic eruption deposited a blanket of tephra (volcanic ash) along the Yukon-Alaska border ~1625 cal BP (calibrated years before present). Currently, there has been limited investigation into the effect of this natural disaster on the environment and local hunter-gatherer populations. This research seeks to analyze and explore the potential ecological and cultural responses to the WRAn event. To address this question, paired archaeological and palynological studies bracketing the WRAn were conducted. Excavations at the Forty Mile/Ch'ëdä Dëk Territorial Historic Site in the Yukon (LcVn-2) revealed a multicomponent site including cultural deposits dating to approximately 1500 and 2000 years ago, with a band of WRAn ash separating them. The focus of the project was to identify similarities and differences in artifactual and faunal assemblages and feature types between cultural occupations pre- and post-tephra deposition that could indicate variations in site use, hunting practices, and tool manufacture. A decadal-scale pollen analysis spanning ~80 years before and after the WRAn tephra fall was conducted on a lake core collected near Eagle, Alaska, to explore the potential environmental impacts of the tephra deposition on the landscape. Results from this project suggest that the WRAn eruption did not create a prolonged negative environmental or cultural impact. At the study location, which experienced at least ~1 cm of tephra deposition, there is a prompt reoccupation of the Forty Mile Site, with multiple subsequent occupations, displaying a resilient population that was able to adapt to the fluctuating environmental surroundings. Similarly, the pollen displays a period of ~5 years of reduced influx and productivity, followed by spikes of abundance before returning to pre-eruptive comparable levels ~35 years after the WRAn. In this thesis, I argue that no hiatus in cultural occupation occurs following the WRAn tephra deposition and the archaeological assemblage displays characteristics in accordance with general cultural transitions occurring in southwestern Yukon and interior Alaskan archaeology.