The Minnelusa Group is defined to include rock units in North Dakota lying above the truncated formations of the Big Snowy and Madison Groups (Mississippian), and below the Opeche Formation (Permian),

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or younger rocks where the Opeche Formation has been removed by pre-Jurassic erosion. Subdivision of the Minnelusa Group into marker-defined units has permitted lithofacies studies that illustrate some of the numerous local and regional stratigraphic variations which provide potential stratigraphic traps for the accumulation of hydrocarbons. An attempt has been made to delineate significant trends exhibiting potential reservoir lithology. Erosional truncation is an important factor and in many places may control possible entrapment within the upper part of the studied interval, because this erosion locally enhances reservoir quality of some units but also may decrease the probability of hydrocarbon accumulation in some areas. Because of the varied and complex depositional and post-dep sitional history of the Minnelusa Group, this interval remains one with high potential for discovery of additional petroleum reserves in North Dakota.

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