Type Geological formation Other breccia Primary Limestone Underlies Stony Mountain Formation | Overlies Winnipeg Formation Country Canada
United States Named for Red River of the North | |
Sub-units Fort Garry Member
Selkirk Member
Cat Head Member
Dog Head Member Thickness up to 215 metres (710 ft) Regions Western Canadian Sedimentary Basin, Williston Basin | ||
The Red River Formation is a stratigraphical unit of Upper Ordovician age in the Williston Basin.
Contents
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.
Subdivisions
The Red River Formation is composed of the following subdivisions from top to base:
Distribution
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.
Relationship to other units
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.
The lower Red River Formation is equivalent to the Yeoman Formation, while the Fort Garry Member correlates with the Herald Formation.