Red River Formation

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Red River Formation
Stratigraphic range: Caradoc to Ashgill
Type Geological formation
Sub-units Fort Garry Member
Selkirk Member
Cat Head Member
Dog Head Member
Underlies Stony Mountain Formation
Overlies Winnipeg Formation
Thickness up to 215 metres (710 ft)[1]
Primary Limestone, dolomite
Other breccia
Coordinates 51°56′54″N 98°03′23″W / 51.9482°N 98.0563°W / 51.9482; -98.0563 (Red River Formation)Coordinates: 51°56′54″N 98°03′23″W / 51.9482°N 98.0563°W / 51.9482; -98.0563 (Red River Formation)
Region WCSB
Williston Basin
Country  Canada
 United States
Type section
Named for Red River of the North
Named by A.F. Foerste, 1929

The Red River Formation is a stratigraphical unit of Upper Ordovician age in the Williston Basin.

It takes the name from the Red River of the North, and was first described in outcrop in the Tyndall Stone quarries and along the Red River Valley by A.F. Foerste in 1929.[2][3]



The Red River Formation is composed of the following subdivisions from top to base: [1]


The Red River Formation reaches a maximum thickness of 215 metres (710 ft) in the center of the Williston Basin. At the along the Manitoba outcrop belt, it is 150 metres (490 ft) thick and thins out northwards.[1]

Relationship to other units[edit]

The Red River Formation is slightly unconformably overlain by the Stony Mountain Formation and sharply overlays the Winnipeg Formation in Manitoba, the Deadwood Formation in western Saskatchewan and the Canadian Shield in northern Manitoba.[1]

The lower Red River Formation is equivalent to the Yeoman Formation, while the Fort Garry Member correlates with the Herald Formation.


  1. ^ a b c d Lexicon of Canadian Geologic Units. "Formation". Retrieved 2010-02-01. 
  2. ^ Foerste, A.F., 1929. The Ordovician and Silurian of the American arctic and sub-arctic regions. Denison Univ. Sci. Lab J., v. 24, p. 27-79.
  3. ^ Foerste, A.F., 1929b. The cephalopods of the Red River Formation of southern Manitoba. Denison Univ. Sci. Lab J., v. 24, p. 129-235.