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 geologic structural basin but not a topographic depression; it is transected by the Missouri River. The oval-shaped depression extends approximately 475 miles (764 km) north-south and 300 miles (480 km) east-west.
The Debolt Formation is a stratigraphical unit of Meramecian age in the Western Canadian Sedimentary Basin.
The Baldonnel Formation is a stratigraphical unit of Carnian age in the Western Canadian Sedimentary Basin.
The Viking Formation is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.
The Woodbend Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Winterburn Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Shaunavon Formation is a stratigraphical unit of Bathonian age in the Western Canadian Sedimentary Basin.
The Pakowki Formation is a stratigraphical unit of Campanian age in the Western Canadian Sedimentary Basin.
The Saskatchewan Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Manitoba Group is a stratigraphical unit of middle to late Devonian age in the Western Canadian Sedimentary Basin.
The Gravelbourg Formation is a stratigraphical unit of Bajocian age in the Western Canadian Sedimentary Basin.
The Big Snowy Group is a stratigraphical unit of Chesterian age in the Williston Basin.
The Interlake Formation is a stratigraphical unit of Silurian age in the Western Canadian Sedimentary Basin.
The Stonewall Formation is a stratigraphical unit of Late Ordovician to Early Silurian age in the Western Canadian Sedimentary Basin.
The Herald Formation is a stratigraphical unit of Late Ordovician age in the Western Canadian Sedimentary Basin.
The Red River Formation is a stratigraphical unit of Late Ordovician age in the Williston Basin.
The Grosmont Formation is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
The Deadwood Formation is a geologic formation of the Williston Basin and Western Canada Sedimentary Basin. It is present in parts of North and South Dakota and Montana in the United States, and in parts of Alberta, Saskatchewan, and southwestern corner of Manitoba in Canada. It is of Late Cambrian to Early Ordovician age and was named for exposures in Whitewood Creek near Deadwood, South Dakota. It is a significant aquifer in some areas, and its conglomerates yielded significant quantities of gold in the Black Hills of South Dakota.
The Alexo Formation a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation consists primarily of dolomite. It is locally fossiliferous and includes remains of marine animals such as brachiopods and conodonts.
The Prairie Evaporite Formation, also known as the Prairie Formation, is a geologic formation of Middle Devonian (Givetian) age that consists primarily of halite and other evaporite minerals. It is present beneath the plains of northern and eastern Alberta, southern Saskatchewan and southwestern Manitoba in Canada, and it extends into northwestern North Dakota and northeastern Montana in the United States.
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