Human and ecological responses to the Northern White River Ash eruption

Thesis (M.A.) University of Alaska Fairbanks, 2020The 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.the Government of Yukon, Archaeology Program and Tr'ondëk Hwech'in First Nation (THFN) Heritage Department, Museum of the North Otto Geist Fund, Frison Institute Patrick Orion Mullen FundChapter 1: Introduction -- 1.1 Case Study Locations -- 1.2 Research Questions and Expectations -- 1.3 Thesis Organization. Chapter 2: Theoretical Approach -- 2.1 Responses to Environmental Catastrophes -- 2.1.1 Evaluating Responses to Volcanic Events -- 2.1.1.1 Environmental Responses -- 2.1.1.2 Cultural Responses -- 2.1.1.3 Ecological Expectations Following the WRAn -- 2.2 Human Behavioural Ecology. Chapter 3: Background of the Study Area -- 3.1 Regional Environment -- 3.1.1 Geography -- 3.1.2 Climate -- 3.1.3 Ecology -- 3.1.4 Volcanism -- 3.1.4.1 White River Ash -- 3.2 Regional Culture History -- 3.2.1 Ethnographic Context -- 3.2.2 Territory -- 3.2.2.1 Relationships Between First Nation Groups -- 3.2.2.2 Population -- 3.2.2.3 Seasonal Round -- 3.2.3 Archaeological Background -- 3.3 Case Study Localities Background -- 3.3.1 Forty Mile Site (LcVn-2) -- 3.3.1.1 Previous Fieldwork and Excavations -- 3.3.2 6-Mile Lake. Chapter 4: Materials and Methods -- 4.1 Pollen Analysis -- 4.1.1 Site Selection -- 4.1.2 Processing and Preparation -- 4.1.3 Pollen Analysis -- 4.1.4 Radiocarbon Sampling -- 4.1.5 Age Model -- 4.1.6 Pollen Diagrams -- 4.2 Archaeological Excavation -- 4.2.1 Site Selection -- 4.2.2 2017 Excavation Methods -- 4.2.3 Artifact Collections -- 4.2.3.1 2017 Excavation -- 4.2.3 Radiocarbon Samples -- 4.2.4 Variables Considered -- 4.2.4.1 Chronology and Stratigraphy -- 4.2.4.2 Faunal -- 4.2.4.3 Lithic Debitage and Artifacts -- 4.2.4.4 Spatial Control -- 4.2.5 Limitations. Chapter 5: Results -- 5.1 The 6-Mile Lake Pollen Core -- 5.1.1 Age Model -- 5.1.2 Percent and Concentration Data -- 5.2 Forty Mile Site (LcVn-2) Excavations -- 5.2.1 Stratigraphy and Site Chronology -- 5.2.2 Spatial Distribution -- 5.2.3 Formal Tools and Other Artifacts -- 5.2.4 Faunal Analysis -- 5.2.4.1 Size Class and Identifiable Fauna -- 5.2.4.2 Taphonomy -- 5.2.5 Lithic Analysis -- 5.2.5.1 Raw materials -- 5.2.5.2 Debitage Attribute Analysis. Chapter 6: Discussion and Conclusions -- 6.1 Vegetation Responses to Tephra -- 6.1.1 Specific Pollen Taxa -- 6.1.2 Seasonality -- 6.1.3 Effects of Environmental Change for Wildlife -- 6.2 Human Responses to Tephra -- 6.2.1 Faunal Material and Subsistence -- 6.2.1.1 Tat'tla Mun Site Faunal Comparison -- 6.2.2 Lithic Material -- 6.2.3 Land Use and Site Function -- 6.2.4 Cultural Chronology Context -- 6.3 Conclusions on the Effects of WRAn -- References Cited -- Appendices