The hoodoos of the Drumheller badlands are among the most photographed rock formations in Alberta, and they fool almost everyone who sees them. They look ancient. They look permanent. They look like they have always been there and always will be. Every part of that impression is wrong. A hoodoo is one of the most temporary things in the whole landscape, and the strange shape that makes it famous is also the reason it is doomed.
What a hoodoo actually is
Strip away the mystery and a hoodoo is a simple, almost comic structure. It is a column of soft rock with a single piece of hard rock balanced on top of it, like a tall thin figure wearing a flat stone hat several sizes too large.
That hat is the entire secret. Geologists call it the caprock, and it is doing exactly one job. It is shielding the soft column directly beneath it from the weather.
It is worth saying where all of this happens. The Drumheller valley is badlands country, a dry and deeply eroded landscape of bare rock and steep coulees, and it is the very same relentless erosion that carves the hoodoos that also strips the valley down to its famous dinosaur bones. The force shaping a hoodoo and the force uncovering a fossil are one process, working on one valley.
How the badlands carve a tower
The Drumheller hoodoos exist because of a process with an unglamorous name and a genuinely beautiful result.
The patience of differential erosion
The badlands are built from layers of rock that wear away at very different speeds. Most of the rock is soft, and southern Alberta’s weather, the rain, the wind, and above all the endless cycle of freezing and thawing, eats through soft rock with surprising speed. But here and there a harder, tougher layer sits on top. Where a chunk of that hard rock holds its ground, it acts as an umbrella. The soft rock directly beneath it is sheltered, while the soft rock all around it is stripped away. Lower the whole landscape by a few metres, leave the protected columns standing, and you have a field of hoodoos.
A recipe seventy million years in the writing
The raw material is genuinely ancient. The rock of the Drumheller valley was laid down in the age of the dinosaurs, roughly 70 to 75 million years ago, as sediment in and around a vast inland sea. The hard caprock holds together because it is cemented with a large share of calcite, which makes it far more resistant than the dark, soft shale below it. The hoodoos themselves, though, are young. They are simply the shape the old rock is passing through, briefly, on its way to becoming flat ground again.
Running out of time
This is the part that surprises people. Hoodoos are not slow. By geological standards they erode at a furious pace, by as much as a centimetre a year, which makes them one of the fastest-changing landforms anywhere on the continent.
And the caprock that protects each hoodoo is itself being worn down the entire time. A day comes for every hoodoo when its stone hat finally erodes through, or slips off, and once that happens the soft column underneath is left bare to the weather. After that the hoodoo does not last long at all. Stand in the Drumheller badlands and you are looking at a slow-motion event. Some of those towers are still forming. Others are within a few years of the end. The field is never quite the same field twice.
Why you should not climb one
This is also why the hoodoos are protected, and why visitors are asked, firmly, to look and not climb. The formations are fragile, the soft rock crumbles under boots and hands, and a hoodoo that might have stood for another century can have years knocked off its life by a single afternoon of people scrambling up it. The site was given provincial historic protection in 2001, and a boardwalk now lets people get close without loving the hoodoos to death.
It is worth the visit, and worth the small discipline of staying off them. The Drumheller hoodoos are a rare thing, a piece of Alberta heritage that is visibly, measurably alive, changing year by year in front of anyone patient enough to look closely. They have been called permanent by every postcard ever printed of them. They are nothing of the sort, and that is exactly what makes them worth seeing now, rather than later.
