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University of North Dakota

Theses and Dissertations

1995

Sedimentation and deposition--North Dakota; Geology

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Depositional Environments And Paleogeography Of The Winnipeg Group (Ordovician), Williston Basin, North Dakota, Jonathan B. Ellingson Jan 1995

Depositional Environments And Paleogeography Of The Winnipeg Group (Ordovician), Williston Basin, North Dakota, Jonathan B. Ellingson

Theses and Dissertations

The Winnipeg Group (Upper Ordovician) unconformably overlies the Deadwood Formation (Cambrian - Lower Ordovician) over most of North Dakota, except in the extreme eastern part, where it lies directly on Precambrian basement rocks. The Winnipeg is conformably overlain by the Red River Formation (Upper Ordovician). The Winnipeg reaches a maximum thickness of 448 feet (136.6 m) in the center of the basin, Williams County. The Winnipeg Group consists of three formations, in ascending order, the Black Island, Icebox, and Roughlock Formations. The Black Island Formation is, herein, formally divided into the Hawkeye Valley and the Garland Members.

The Hawkeye Valley …