Obsidian Artifacts in Alberta Reveal Vast, Ancient North American Trade Networks

Over 500 archaeological sites across western Canada have yielded a striking discovery: sharp-edged, inky black fragments of volcanic glass, which would have been used by ancient Native Americans as hunting tools. While they may seem ordinary in comparison to similar artifacts foud elsewhere, these obsidian shards reveal a story that has remained hidden in the historical record up to now.

Obsidian is the name for this type of volcanic glass rock, and it is not native to Alberta (no volcano has ever erupted in the province). Yet, archaeologists continue to unearth arrowheads and spear tips crafted from this substance, which is naturally smooth and hard and forms when molten lava cools rapidly. These finds are anomalous, and they provide strong evidence of vast trade networks built and maintained by Indigenous peoples long before European contact.

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The Alberta Obsidian Project: Expectations Exceeded

Researchers are using modern technology to trace the origins of these fragments, which is allowing them to map the extensive movements of people and materials across North America as recently as 300 years ago, and as far back in the past as 13,000 years ago.

The Alberta Obsidian Project is a long-term study to analyze, catalog, and research obsidian found at archaeological sites across the province. A recent study it sponsored focused on artifacts discovered along Alberta’s eastern slopes, which offer fresh insights into how bison hunting grounds in the southern foothills and intricate trade routes in the province’s north helped spread obsidian tools over such vast distances.

Archaeologist Timothy Allan, the study’s author and a researcher with Ember Archaeology based in Sherwood Park, Alberta, set out to understand how Alberta fit into an expansive trade network that once spanned over three million square kilometers.

Shards of obsidian glass that could have been attached to spears or arrows, found at archaeological sites throughout Alberta. (Archaeological Survey of Alberta).

“The sheer scale of obsidian trade tells us that likely millions of people were in contact with one another,” Allan said in an interview with the CBC. “The scope of the trade network was way more massive than we thought.”

Obsidian pieces often changed hands multiple times, weaving through a web of communities and landscapes. Allan believes tracing these journeys can provide a deeper understanding of not only migration and settlement patterns but also the complex cultural and social relationships that connected diverse Indigenous communities across the continent.

“It’s definitely part of our role in reconciliation, as archaeologists, to help tell these stories,” he said.

The findings were published by the Archaeological Survey of Alberta, which supports the Alberta Obsidian Project.

Obsidian Breadcrumbs Marking Ancient Trade Routes

Over the last decade, researchers working with the Alberta Obsidian Project have analyzed more than 1,200 obsidian artifacts. These tools and weapons date from between 13,000 and 300 years ago, or well before Europeans arrived in the region.

Over 520 sites in Alberta have produced obsidian artifacts, with the eastern slopes of the Rocky Mountains and their foothills providing the richest collection. In that area alone, obsidian has been found at 285 sites. Allan’s latest analysis focused on 383 pieces from 96 of those locations.

Illustration showing the ancient obsidian trade routes that supplied Alberta’s native peoples. (Timothy Allan/Archaeological Survey of Alberta).

Obsidian is the sharpest naturally occurring material known to science. Its razor-thin edges made it ideal for the cutting and piercing tools used by Indigenous hunters and craftspeople. Today, those same qualities help archaeologists determine where the material originated. Every piece of obsidian contains a unique chemical fingerprint formed during its creation. Using X-ray fluorescence, researchers can analyze these chemical signatures and trace each shard back to its volcanic source.

“It’s formed when a volcano erupts and lava cools really, really quickly,” Allan explained. “Because it cools so quickly, it kind of seals its chemistry in time.” That chemistry serves as a marker of the rock’s birthplace. “If you find obsidian [in Alberta], you know that that material has travelled a long way.”

Allan’s study suggests that the territory of ancient Alberta marked the northern frontier of an extensive network of obsidian exchange. This network stretched south through the American Midwest, reaching as far south as Texas, and extended northward to areas near modern-day Fort McMurray, Alberta.

Artifacts found in Alberta typically traveled between 250 and 750 miles (400 and 1,200 kilometers) from their origin. Most came from Bear Gulch in Idaho and Obsidian Cliff in Yellowstone National Park, Wyoming in the modern western United States. Lesser but still significant sources include Mount Edziza and Anahim Peak in British Columbia, directly to the west of Alberta.

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The data shows that about 62% of the analyzed obsidian in Alberta originated from Bear Gulch, while roughly 30 percent came from Obsidian Cliff. Interestingly, distinct routes emerged along natural landscape features. The North Saskatchewan and Red Deer Rivers seem to have acted as boundaries, dividing the major trade paths from one another.

In the province’s northern regions, Indigenous groups appeared to have been more closely tied to western communities. Trade was sporadic and likely followed major east-west river systems that cut through the Rocky Mountains, providing natural corridors for the movement of goods like obsidian pieces.

Conversely, in southern Alberta, the trade of obsidian appears to have been more organized and frequent. Communal bison hunts were central to life in the foothills and plains, and these events undoubtedly facilitated the exchange of tools and materials. Obsidian traveled in greater volumes here, likely as part of extensive social and economic networks that spanned the prairie provinces and the American Midwest.

The Canadian Rockies in Alberta in Banff National Park, near sites that have produced obsidian glass artifacts. (Sergey Pesterev/CC BY-SA 4.0).

Bison jump sites—where herds of animals were driven off cliffs during large communal hunts—hold some of the highest concentrations of obsidian artifacts in Alberta, further tying trade activity to these culturally significant events.

A Glimpse into Prehistoric Adaptation

According to Todd Kristensen, a regional archaeologist with the Archaeological Survey of Alberta, the movement of obsidian offers valuable insights into the ways different groups adapted to and interacted with their environments.

“We can use obsidian to understand how different Indigenous groups in different ecological regions adapted to the landscape differently,” Kristensen said. “It’s one of those little portals that we can use to understand how people adapted.”

The story of obsidian in Alberta is synonymous with the province’s prehistoric patterns of social and cultural development. These black glass shards had enormous value to ancient Indigenous people, and helped to sew together peaceful, long-distance trade networks that promoted prosperity everywhere.

Top image: Samples of obsidian arrowheads that have been found at archaeological sites in Alberta.

Source:  Alberta Obsidian Project.

By Nathan Falde