Nature
The Stony Mountain Formation is an Ashgill-age geologic unit in the Western Canadian Sedimentary Basin, named for Stony Mountain, Manitoba, where D.B. Dowling first described it in 1900 from the town quarry. It extends through the Williston Basin and is exposed in Manitoba’s erosion belt. About 30 metres thick there, it reaches up to 45 metres in the subsurface near the Canada–United States border before thinning eastward, northward, and westward. Its rock types vary regionally, with different named members in the south and north, and in the local sequence it rests above the Red River or Herald formations and is overlain slightly unconformably by the Stonewall Formation.
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Manitoba · Canada