Paleontology and geologyAlthough no rocks of Permian age are shown on this map, exposures of these rocks do occur in a number of outcrops in the Bighorns, Black Hills, and several other mountain ranges throughout the state. These rocks are mainly limestones and shales, with some sandstones evaporites are also common, recording the retreat of the sea from Wyoming. Fossils include brachiopods, as well as occasional sponges, horn corals, bryozoans, pelecypods, gastropods, belemnites, ostracods, conodonts, and fish. |