The Stony Mountain Formation is a

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characteriz ...

Ashgill Ashgill is a village in South Lanarkshire, Scotland near Larkhall. It is part of the Dalserf parish. The village church dates back to 1889. It is twinned with Saint-Cirq-Lapopie in France. The village has a shop, a chip shop and a hairdress ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the

Western Canadian Sedimentary Basin The Western Canada Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary b ...

. It takes the name from the community

Stony Mountain, Manitoba Stony Mountain is a small community in Manitoba, Canada approximately north of Winnipeg on Provincial Highway 7. The town is in the Rural Municipality of Rockwood and is the location of Stony Mountain Ski Area. The Stony Mountain Institution ...

, and was first described in the town quarry by D.B. Dowling in 1900.Dowling, D.B., 1900. Report on the Geology of the West Shore and Islands of Lake Winnipeg;

Geological Survey of Canada The Geological Survey of Canada (GSC; , CGC) is a Canadian federal government agency responsible for performing geological surveys of the country developing Canada's natural resources and protecting the environment. A branch of the Earth Science ...

, Annual Report 1898, Volume XI, Part F, with Map 664.

Lithology

Subdivisions

The Stony Mountain Formation is divided in the following sub-units: ;South (

Williston Basin The Williston Basin is a large intracratonic sedimentary basin in eastern Montana, western North Dakota, South Dakota, southern Saskatchewan, and south-western Manitoba that is known for its rich deposits of petroleum and potash. The basin is a ...

) * Penitentiary Member: argillaceous dolomite * Gunn Member: interbedded calcareous

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

and

fossiliferous limestone Fossiliferous limestone is a type of limestone that contains noticeable quantities of fossils or trace fossil, fossil traces. If a particular type of fossil dominates, a more specialized term can be used as in "Ames Limestone, Crinoidal", "Coral ...

;North * Gunton Member: crystalline dolomite *Lower Stony Mountain: argillaceous dolomite

Distribution

The Stony Mountain Formation occurs throughout the

. It reaches a maximum thickness of in the sub-surface at the

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

border, and thins out towards the east, north and west. In

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, where it is exposed at the surface in the erosion belt, it has a thickness of .

Relationship to other units

The Stony Mountain Formation is slightly

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

overlain by the Stonewall Formation and sharply overlays the Red River Formation or the Herald Formation.

References

{{Western Canadian Sedimentary Basin, Saskatchewan=yes Geologic formations of Saskatchewan Geologic formations of Manitoba Ordovician geology of North Dakota Dolomite formations of Canada Shale formations of Canada Limestone formations of Canada Limestone formations of the United States Western Canadian Sedimentary Basin Shale formations of the United States Dolomite formations of the United States