In the northern Black Hills, Middle (?) Ordovician fossils have been found to occur throughout approximately 70 feet of shale and siltstone beds immediately below the typical Whitewood dolomite. These beds and their faunas are discussed, and it is concluded that the strata involved should be included tentatively, at least, with the overlying Whitewood formation (Ordovician), rather than with the underlying Deadwood formation (Cambrian) as has been done heretofore.

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