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On Red Fork of Powder River south of the 7 turn as locally called in the outer ridge of the Big Horn into the Triassic formation Is about 800 ft thick, the lower beds highly gypsiferous some places gypsum five to six ft thick. This lower series is about 200 ft thick. Above this the beds present alternating strata of shale and sandstone with heavy lighter stratum on top eroded in pit + hole like depressions Between this and the Jurassic is about 40 ft of white coarse grayish unfossiliferous sandstone sometimes ???? which is difficult to determine Above this sandstone the Marine Jurassic is about 80 ft thick containing ??? Belemnites etc A greenish grey marl alternating with sandstone and considerable limestone containing a great deal of fossil wood and chalcedony