Frank Slide

Driving through Crowsnest Pass in the far southwest corner of Alberta, you come around a bend and the valley floor is suddenly, inexplicably covered in boulders — not scattered rocks, an entire square kilometre of jumbled limestone chunks the size of cars and small houses, spreading from the base of Turtle Mountain right across the valley and partway up the opposite slope. It looks less like a natural landscape than a demolition site, because that’s essentially what it is. At 4:10 in the morning on April 29, 1903, roughly eighty-two million tonnes of the mountain’s eastern face broke away and slid into the valley in under two minutes, burying part of the town of Frank and killing somewhere between seventy and ninety people, most of whom were never recovered from beneath the rock.

I stopped at the interpretive centre built on the edge of the slide and the exhibits do a careful, unflinching job of explaining both the geology and the human toll — coal mining beneath the mountain, unstable limestone layers, a wet spring, and a particularly cold night all combining at the worst possible moment. What stayed with me longest was a photograph of the mountain from before the slide next to one from after: an entire section of peak simply missing, a raw grey scar where Turtle Mountain used to have a summit. The Piikani and Ktunaxa peoples reportedly called it “the mountain that moves” long before the disaster, having noticed the instability generations earlier.

Walking the interpretive trail out onto the boulder field itself is a strange experience — the rocks are enormous, some the size of small buildings, and they sit exactly where they came to rest more than a century ago, still largely bare of soil or significant vegetation because limestone this size breaks down so slowly. Part of the original townsite and the old highway both remain buried somewhere beneath the debris, and the trail signage marks approximately where houses and a section of railway once stood before that morning. It’s a somber place rather than a scenic one, but Turtle Mountain is still geologically unstable today, monitored continuously, and standing at the base of it looking up at that scar gives you a genuinely different relationship to the word “mountain” than anywhere else in Alberta.

When to go: The interpretive centre is open year-round with reduced winter hours, but late spring through early fall gives full access and lets you walk the outdoor trails through the boulder field comfortably.