Among all the sedimentary formations in Wyoming there is probably none more persistently and fully exposed along its outcrops than the early Paleozoic dolomite, which Darton2 has called the Bighorn limestone. So massive are its beds that in many places it seems to consist of but a single stratum 100 to 300 feet thick. By breaking off along vertical joints the formation leaves continuous and often impassable cliffs where the beds are not highly inclined, or rises in sharp “hogback” ridges where the dip is steep. Other Paleozoic terranes, such as the Madison limestone and the Tensleep sandstone, make cliffs and ridges, but none so uniform and persistent as the Bighorn dolomite. The individuality of its exposures is such that by one sufficiently acquainted with its peculiarities the outcrops may be recognized miles away.
Figure 1.—Outline Map of the Region within which the Bighorn Dolomite has been . . .