The Big Rock near Okotoks, Alberta is the world's largest glacial erratic. The rock is larger than a house and is 41 meters long, 18 meters wide and 9 meters high. This glacial erratic sits in the middle of prairie field and was transported to the Okotoks area during the last ice age. From the mineral composition, the rock was determined to be from the Rocky Mountains near Jasper, Alberta - almost 300 kilometers away!
The Okotoks Big Rock is a part of series of glacial erratics making up the Foothills Erratic Train, a narrow band stretching from Jasper to northern Montana, USA. It's the longest erratic train in Canada. In the Calgary region, a large number of boulders can be found along the river and creek valleys.
The Big Rock of Okotoks weighs over 16,500 tonnes and has been eroded over the centuries. Sections have collapsed and have broken into smaller pieces. This glacial erratic has been named a provincial historical site and should not be climbed (even though I've always seen people on top).
View Glacial Erratic - The Big Rock of Okotoks, Alberta in a larger map
You can't miss it; the Big Rock is located along Highway #7, five minutes southwest of Okotoks, Alberta. The parking lot is located just off the highway and access is an easy stroll of approximately 200 meters.