Ecological Catastrophes in Alberta’s Past: The Mazama Volcanic Eruption

Did you know that one of the largest ecological catastrophes in Alberta’s human history was a volcanic ash fall? Around 7600 years ago the skies were blackened for many days and the prairies of Alberta were blanketed with roughly 15 cm of ash ejected during the Mazama eruption.

To create awareness of this event and other important moments in Alberta’s past, a team from the Historic Resources Management Branch, the University of Alberta, and the Royal Alberta Museum initiated a project called the Heritage Art Series.  The goal is to captivate public audiences with artwork that creatively explores ancient landscapes, relationships between people and their surroundings, and the enduring physical record of human activities. We hope the series inspires a desire to learn more about our province’s heritage and that a greater awareness of the past will instill a deeper respect for it. We’ll release the first four paintings in the series over the coming weeks with explanations about the significant events and figures that each scene depicts.

The first painting (above) by Karen Bishop captures a surreal landscape of Southern Alberta as it would have looked 7600 years ago during the Mazama volcanic eruption. While the volcano that erupted was in Oregon (at modern day Crater Lake), it only took about 12 hours for some of the estimated 100 km³ of ash to reach Alberta. The ash smothered plants, contaminated fresh water, and would have filled animals’ lungs. Airborne particles would have caused intense lightning storms. Huge swaths of dead vegetation combined with frequent lightning led to widespread fires.

Mazama ash distribution and depth diagram

This map shows the spread of Mazama ash into Alberta. The inset depicts the depth of Mazama ash relative to people and dogs.

Ash depth comparison

This figure depicts how deeply Edmonton and Calgary would be buried if all of the ash from the Mazama eruption were confined to the city limits.

By studying micro-organisms and microscopic silica particles in soils and lake beds, scientists, including a team of ‘tephrochronologists’ led by Dr. Duane Froese from the University of Alberta, are learning more about the ecological impact and timing of volcanic eruptions in Western Canada. Climatic systems were altered by the relatively dense ash ejected into the atmosphere, the pH of soils and water bodies changed, and mobile animals like bison likely abandoned their territories for lack of fodder and/or drinking water. However, while the impact was widespread, preserved pollen suggests that plant communities rebounded rapidly. Overall, landscapes may have recovered fairly quickly from volcanic eruptions (on the scale of 2-10 years), but the effect on human populations was likely more pronounced.

Diatoms

Silica particles for blog

The archaeological record reveals that portions of the province were abandoned for several decades and possibly much longer. Notable changes in weapons and raw materials that were used for stone tools around the time of the Mazama eruption may be linked to this ecological catastrophe; the people that returned to once-vacated landscapes were either different from their predecessors or they arrived with new ideas acquired from their neighbours. This, and other large-scale eruptions in North America over the past 10 000 years, changed the direction of local human histories. New cultures, technologies, and social networks emerged after volcanic events.

Projectile points in Alberta

Despite the dramatic nature of volcanic eruptions, few people realize that Alberta has experienced them in the past and that other ecological catastrophes have influenced the development of Alberta’s past cultures. Palaeoenvironmental scientists and archaeologists have learned a great deal about past ecological events that, while educational, have more profound implications for the way we manage ecosystems and respond to the world around us. By studying the past, we can learn how to brace for the future.

To learn more about the Mazama eruption and other palaeoenvironmental studies in Alberta, visit some of Dr. Alwynne Beaudoin’s research at the Royal Alberta Museum.

Stay tuned for the next installation of the Heritage Art Series, which will discuss the archaeological and historical records of First Nations fishing in Northern Alberta.

Written by: Todd Kristensen, Northern Archaeologist & Alwynne Beaudoin, Royal Alberta Museum.

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