The report area includes approximately 200,000 square miles in the southern part of the Williston basin of North Dakota, South Dakota, and eastern Mon- tana and in central Montana and north-central Wyoming. Devonian ...

The Souris River area comprises about 5,500 square miles in north-central North Dakota. It is bounded roughly by the east loop of the Souris River on the east, by the Max moraine on the southwest, and by the International ...