Pg. 136 (chart 1), 138-140, 143 (fig. 2), 145 (fig. 3). Allan Hollow shale member of Frontier formation. Dark-gray marine shale with interbedded thin sandstone at base and top. Thickness 780 feet. This occurrence of marine shale represents parts of section by faulting. Only complete surface section found on northwest flank between crest of [Coalville] anticline in sec. 6, T. 2 N., R. 6 E., and Grass Creek Valley 3.5 miles north-northwest. Formation, where it occupies northwest flank, partly covered by unconformable overlap of Knight formation and cut by several normal faults. Overlies Coalville member (new) of Frontier. Age is Late Cretaceous (middle Turonian). Contains COLLIGNONICERAS WOOLGARI, an early Carlile fossil.

Source: US geologic names lexicon (USGS Bull. 1200, p. 52-53); supplemental information from GNU records (USGS DDS-6; Denver GNULEX).