Also known as the “Big Rock”, this interesting formation is situated 7 km west of the small city of Okotoks, south of Calgary. “Big Rock”, as its locally known, can be seen from some distance because of the area’s flat prairie landscape.
Big Rock is an enormous glacial erratic. It measures 9 meters tall, 41 m long,18 m wide, and weighs 16,500-tonne (18,200-ton). While there are thousands of erratics in Alberta and Montana, this is the largest known erratic in the world.
(courtesy of the Alberta government)
Big Rock is made of quartzite and was transported from its origin in Jasper National Park. The erratic fell in a rockslide and was then carried south by a glacial sheet of ice between 10,000 to 30,000 years ago. The Okotoks Erratic was deposited here when the glaciers began to melt and recede.
In 1978, the Government of Alberta designated the Okotoks “Big Rock” Erratic a Provincial Historic Resource, protecting it.
The photos below show the lovely summertime views from the Erratic, of the surrounding canola fields and distant Rocky mountains.
