The lower and upper contacts of the Upper Jurassic Bluff Sandstone Member of the Morrison Formation in southeastern Utah
— Robert B. O'Sullivan

An eolian sandstone, about 92 m thick, forms cliffs around the town of Bluff, Utah. The unit includes what has been termed the Bluff Sandstone Member of the Upper Jurassic Morrison Formation, but its base has been placed at 6 different levels within a stratigraphic interval of about 39 m by various geologists. This has led to much uncertainty as to where the contact with the underlying Middle Jurassic Wanakah Formation is best defined. The top of the member has also been placed at 2 different stratigraphic levels, about 24 m apart.