The Bakken Formation is located in western North Dakota, eastern Montana, and southern Saskatchewan, Canada, as a subsurface formation within the Williston Basin. The Williston Basin extends to southwestern Manitoba, east-central North Dakota, northwestern South Dakota, eastern Montana, and southern Saskatchewan. The central and deepest basement location is approximately 15,000 feet, near Williston, North Dakota. Major structural features within the basin include the Nesson and Cedar Creek Anticlines.
The Bakken Formation lies between the overlying Lodgepole Formation, which is conformable in most areas, and the underlying Three Forks Formation, which is unconformable. The Bakken Formation is both Devonian and Mississippian in age as the chronostratigraphic contact lies approximately within the upper portion of the middle member. This contact is based largely on studies of conodont fossils1 present within the formation. The stratigraphic units in the image to the right represent a time period that lasted from 416 to 318 million years ago. The Bakken Formation was deposited approximately 360 million years ago.