Big Rock (glacial erratic)
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Big Rock (also known as Okotoks Erratic) is a glacial erratic situated between the towns of Okotoks and Black Diamond, Alberta, Canada (18 kilometres south of Calgary). The 15,000 tonne (16,500 short ton) quartzite boulder is the world's largest known glacial erratic.[1]
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[edit] History
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.[2] Big Rock was transported on the Cordilleran Ice Sheet approximately 12 to 18 thousand years ago[3] 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" [ˈo.kə.tok], 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.[2]
[edit] Present day
The erratic is clearly visible from the side of Highway 7, and public parking is available at the turn-off. While there is a fence around the Big Rock, thousands of people visit the rock and either boulder or climb the 9 metre tall erratic.
Erosion has caused noticeable signs of mass wasting documented in 1991.[citation needed]
[edit] In popular culture
Since 1985, Big Rock Brewery has been in business, brewing beer in honour of Big Rock.
[edit] References
- ^ Alberta museum historic site: Okotoks Erratic. Alberta Government: Tourism, Parks, Recreation and Culture.
- ^ a b Lionel E. Jackson, Jr., Elizabeth R. Leboe, Edward C. Little, Philip J. Holme, Stephen R. Hicock, and Kazuharu Shimamura. "CANQUA 99 Guidebook: Late Quaternary Geology of the Foothills, from Calgary to the Alberta–Montana Border".
- ^ Jackson, Lionel E.; Fred M. Phillips, and Edward C. Little (1999). "Cosmogenic 36Cl dating of the maximum limit of the Laurentide Ice Sheet in southwestern Alberta". Canadian Journal of Earth Sciences 36 (8): 1347–1356. doi:.
