About 7 km west of the town of Okotoks in Alberta, in Canada, on the flat prairie lies a massive piece of rock 41 meters long, 18 meters wide and 9 meters high, and weighs 16,500 tons. It’s a glacial erratic - a rock transported far from its place of origin by glacial ice thousands of years ago. The Okotoks Erratic, also known as “the Big Rock” is the world's largest known glacial erratic. In fact, the name of the town – Okotoks – is itself derived from the word “ohkotok” which means “rock” in the Blackfoot language.

The rock is one of several thousand erratics found in Alberta and Montana lying along a narrow band extending from Jasper National Park to northern Montana called the Foothills Erratics Train. The erratics train originated from a landslide in the Tonquin Valley of Jasper National Park, and was transported along the confluence of the Cordilleran Ice Sheet and the Laurentide Ice Sheet approximately 12 to 18 thousand years ago to its present location.

Photo credit