Effects of the White River and Mazama Tephras on Terrestrial and Aquatic Palaeoenvironments in Western Subarctic Canada, and Implications for Past Human Populations

• Main Author: Rainville, Rebecca
• Other Authors: Callaghan, Richard, Kooyman, Brian, Oetelaar, Gerald
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Arts 2016
• Subjects: Archaeology; History > Canadian; Paleoecology; volcano; Canada; subarctic; palaeoecology; Yukon; Spirit Lake; Subarctic
• Online Access: http://hdl.handle.net/11023/2740; https://doi.org/10.11575/PRISM/25836

This study presents new information regarding the environmental impacts of the eastern White River (WRA; 1147 cal BP) and Mazama (MZA; 7627 cal BP) tephras in the western Canadian subarctic, and discusses their potential implications for wildlife and human populations in the affected regions. Sediment cores were collected from two lakes (Spirit Lake, southern YT; “Marahbodd” Lake, western NWT) within the fallout of the WRA and one (Goldeye Lake, western AB) within the fallout of the MZA. Pollen, microcharcoal, chironomids, and sedimentary characteristics were examined to reconstruct terrestrial and aquatic environments before and after the eruptions. The results show noticeable environmental impacts of the WRA and MZA at the sites, including on terrestrial and aquatic community composition and productivity, fire activity, landscape stability, and lake conditions and chemistry. Environmental impacts were most pronounced at Spirit Lake, the site closest to the source of its eruption, where the data suggest that the availability of water, food, material, and habitat resources would likely have been considerably reduced for 50-150 years. The data support archaeological, ethnographic, and linguistic evidence that suggests that the WRA might have stimulated wildlife (notably caribou) and human population movements out of the region, and human adoption of the bow-and-arrow and of bone and antler points. Data from “Marahbodd” Lake suggest that the environmental impacts of the WRA were likely similar to those at Spirit Lake, but lesser in degree – though they lingered longer. The data support archaeological and ethnographic evidence of limited impacts of the WRA on local wildlife and human populations, which suggests that populations did not leave the region after the eruption – or at least not on the scale apparent in southern Yukon. At Goldeye Lake, the data indicate that the environmental impacts of the MZA were generally slight, though long lasting. A period of reduced occupancy of Plains environments after the MZA ...