Stonewall Formation
{{Infobox rockunit
| name = Stonewall Formation
| image =
| imagesize =
| caption =
| type = Geological formation
| age = {{Fossil range|Late Ordovician|Early Silurian|Ashgill to Alexandrian}}
| prilithology = dolomite
| otherlithology = Sandstone, anhydrite
| namedfor = Stonewall, Manitoba
| namedby = E.M. Kindle, 1914
| region = WCSB
Williston Basin
| country = Canada
| coordinates = {{coord|50.1186|N|97.7239|W|display=inline,title|name= Stonewall Formation}}
| unitof =
| subunits =
| underlies = Interlake Group
| overlies = Stony Mountain Formation
| thickness = up to {{convert|34|m|ft|-1}}
| extent =
| area =
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File:Williston Basin stratigraphic column.jpg
The Stonewall Formation is a stratigraphic unit of Late Ordovician to Early Silurian age in the Western Canadian Sedimentary Basin.
It takes the name from Stonewall, Manitoba, and was first described in the Stonewall quarry by E.M. Kindle in 1914.Kindle, E.M., 1914. The Silurian and Devonian Section of Western Manitoba; Geological Survey of Canada, Summary Report 1912, pp. 247-261.
Lithology
The Stonewall Formation is composed of finely crystalline dolomite, with a basal argillaceous and sandy dolomite (the Williams Member). Two thin sandstone beds occur in the middle and at the top of the formation.
{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:014592
|title= Stonewall Formation
|author=Lexicon of Canadian Geologic Units
|accessdate=2010-02-03}}
In the central Williston basin, the base is marked by an anhydrite bed.
Distribution
The Stonewall Formation occurs at surface in the Manitoba outcrop belt and in the sub-surface in the Williston Basin. It reaches a maximum thickness of {{convert|34|m|ft|-1}}.
Relationship to other units
The Stonewall Formation is overlain by the Interlake Group (conformably in the south, disconformably in the north) and sharply overlays the Stony Mountain Formation.
References
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{{Western Canadian Sedimentary Basin|Saskatchewan=yes}}
Category:Ordovician Saskatchewan
Category:Silurian Saskatchewan
Category:Western Canadian Sedimentary Basin
Category:Geologic formations of Manitoba
Category:Geologic formations of Saskatchewan
Category:Ordovician southern paleotropical deposits