Big Rock Roadside Attraction in Okotoks Alberta
Province of Alberta Home to Glacial Erratic Travel Attraction
Nov 16, 2009
The Big Rock is a stranger in a strange land. The monstrous block of Rocky Mountain quartzite weighing 16,500 tonnes and measuring about 41 x 18 x 9 metres, rests in a prairie field just off Highway 7 about 10 km southwest of Okotoks, clearly out of place.
About Glacial Erratics
A glacial erratic is any rock carried away from its original location by the action of glacial ice. The erratics may be pushed bulldozer-like by the leading edge of the glacier but are most often dropped onto the top of the ice by frost heaves and avalanches. The debris is funneled into channels in the glaciers as they flow and intersect.
When the ice melts, the debris is left usually in the form of a moraine, a high ridge or series or rolling hills. Solitary erratics such as the Big Rock are not uncommon, but the Okotoks Erratic is the largest of its kind in the Foothills Erratics Train, a string of erratics deposited along the foothills from Jasper National Park to northern Montana at the end of the last ice age some 10,000 years ago.
The Big Rock Blackfoot Story
The Blackfoot, a prairie First Nations people, have a story that explains both why the rock is there and why it is split in two. This is only a brief summary; read the full story on the information signs at the Big Rock roadside attraction site.
Napi, the trickster, had given his cloak to the Big Rock, but later reclaimed it when the weather turned cool. Angry, the rock rolled after him. Bats flew into the rock, smashing it to a stop. This also explains why bats have smashed-in faces.
The Big Rock Scientific Story
According to Alberta Culture, an avalanche on Mount Edith Cavell tumbled Big Rock and other debris onto a glacier in the Athabasca River valley around 18,000 years ago. The rock was borne on a slow journey as the glacier flowed east and south under geological forces. When the ice age ended some 10,000 years back, a string of erratics was deposited along the foothills, with Big Rock the largest.
In 1978, the Big Rock was the first natural feature to be designated as an official provincial historic site.
A roadside attraction only fifteen minutes from Okotoks and about 30 minutes from Calgary, the Big Rock is a good place to stop and stretch the legs. Despite the "no climbing" signs, kids (and most adults) will be unable to resist a scramble to the top.
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