Did volcanic eruptions in Canada’s deep past affect Indigenous people?

Written by: By Dr. Todd Kristensen, Archaeological Survey of Alberta

Archaeologists compare records before and after ancient volcanic eruptions to understand how the lives of people changed. Impacts of ecological disasters on humans can be detected along local and broad scales: how did Indigenous people cope at a specific site and how did human relationships change across vast regions? A massive eruption 1,200 years ago, called White River Ash East, changed the way that people in northern Canada hunted and gathered in areas affected by volcanic ash, which fell in beds up to 1 m thick. Beyond the ash footprint, human networks were forever altered, with ripple effects that spread through Alberta and North America.

A volcano in Alaska sent ash east across southern Yukon, southwest NWT, and into northwest Alberta. Geologists study beds of ash (tephra) to reconstruct the size of eruptions. The shaded colours are rough estimates of how thick the volcanic ash is. Source: Todd Kristensen.
Ash depth relative to people (top). When the ash originally fell, it was loose and deep but would’ve compressed over time (top right inset). Based on other eruptions, the White River Ash East tephra may have shrunk up to 50% in the following decades after it fell. At bottom is an estimate of ash thickness in current sediments with the original ash thickness in brackets. Source: Todd Kristensen.
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