The Big Rock (glacial erratic)

This is the 'Big Rock' near Calgary Alberta (between Okotoks and Black Diamond).

It is a rather large chunk of rock deposited by receding glaciers during the last Ice Age (known as a glacial erratic).

It is also the namesake for the Big Rock Brewery, a famous local brand of beer.

Big Rock is one of several thousand erratics found in Alberta and Montana called the Foothills Erratics Train, which originated from a landslide in the Tonquin Valley of Jasper National Park, from Lower Cambrian-aged Gog Group. Big Rock was transported on the Cordilleran Ice Sheet approximately 12 to 18 thousand years ago to its present location.

The people of the Blackfoot First Nation used Big Rock as a landmark for finding a crossing over the Sheep River (where Okotoks stands today) long before European settlement. The town's name Okotoks is derived from "o'kotok" [ˈokətok], meaning "Large Rock" in the Blackfoot language.

The first geologist to discover Big Rock was James Hector in 1863, who misidentified the feature as a klippe.