If you’re walking just east of Calgary’s Coventry Hills neighborhood, you might dismiss it as just plain old rock covered in graffiti.
But for Lincoln Friske, it’s a local treasure.
A large erratic boulder is located just past Nose Creek Park. Friske visits the massive rock during his daily dog walks and recently decided to create a digital 3D model of it so others can appreciate it.
“It was built right as an anomaly in the middle of this massive park,” he said in an interview with the Calgary Eyeopener. “Most people didn’t even know there was this unusual graffiti in our own backyard.”
Erates are stones, boulders or large blocks picked up and moved by glaciers from one place to another during the last ice age.
Thousands dot the foothills, part of a 600km stretch known as the Foothills Erratics Train. It stretches from around Hinton, Alta., all the way to the Montana border.
WATCH | Check out Friske’s 3D rendition of erratic below:
Eva Enkelman, an associate professor in the University of Calgary’s geoscience department, says the stones usually look out of place.
“It almost looks like it fell from the sky. That means it doesn’t really match the rocks you find in that area,” she said.
The stones are usually white, gray or slightly pink.
They’re made of quartzite — or cemented sand grains — dating back about 500 million years, according to Dale Leckie, geologist and author of The Scenic Geology of Alberta: A Roadside Touring And Hiking Guide.
This large boulder is located in Nose Hill Park, part of the Foothills Erratics Train. (Submitted by Dale Leckie)
The researchers traced the material to Mount Edith Cavell in Jasper National Park, about 300 kilometers northwest of Calgary.
“They’re a very distinctive kind of rock,” Leckey said.
“You can see features inside them that geologists call cross-bedding. They are structures from the waves and tides when they were deposited.”
So how did they get here?
About 20,000 years ago, a landslide occurred in Jasper National Park.
The rolling boulders fell on valley glaciers in the Athabasca River Valley. They drifted north, then east, then bumped into the Laurentide Ice Sheet, which covered most of Canada at the time, and were redirected south, Leckie said.
Over time, they spread across the Foothills.
“When the ice melted, it ended up just letting them down, I’ll say almost gently, onto the landscape, slipping, sliding back and forth,” Leckie said.
The Foothills Erratics train runs from around Hinton, Alta., all the way to the Montana border. (Government of Alberta)
Most of the erratic stones landed in their current resting places about 16,000 years ago.
Another distinguishing feature is how solid the irregularities are, Enkelman said.
“Only stones that are very, very hard actually survive such a long transport,” she said. “The river usually went around the stones and eventually they turned into pebbles.”
However, if you look closely, some of the stones do have rounded edges on their lower parts.
That’s because hundreds of years ago, bison rubbed against the rocks to shed their winter coats, Leckie said, creating more polished pieces. They also created depressions around the stones known as buffalo rollers.
Where are they?
You can come across random rock in many farmers’ fields passing through the Rockies, Leckie said, but some of the rocks have become famous landmarks.
The largest and most famous example would be Okotoks, also known as the Big Rock, which is about the size of a three-story apartment building. There is also a 3D model of the strange available courtesy of the University of Calgary.
Okotoks is protected by the Government of Alberta for its geological and cultural significance. (Submitted by Dale Leckie)
The province designated Big Rock a Provincial Historic Resource in 1978 to protect its geological and cultural significance.
“I think they’re so interesting because they’re just giant blocks,” Leckey said.
“They really draw your attention … they just pop out in the landscape because they stand tall almost like sentinels.”
Several notable mayhems are located in Calgary, including one documented near Coventry Hills.
One sits atop Nose Hill Park. Another, known as Split Rock, is in the northeast part of town, just off Harvest Hills Boulevard and Beddington Trail NW
Split Rock can be found at Confluence Park in the Beddington Heights neighborhood of Calgary. (Submitted by Dale Leckie)
Leckie has seen others at Lake Mackenzie Playground and Tuscany Recreation Area. At Panorama Hills in a small park is an erratic rock, sometimes called Crater Rock.
There are hundreds more, Enkelman says, and once you’re aware of them, you’ll start noticing them everywhere.
“It’s fascinating to me that you can weave this whole story by looking at these chaos here in the city, where we’re relatively far from the mountains, but we have this evidence,” she said.
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