Paleontology and geologyAlthough no rocks of Cambrian age are shown on this map, small exposures of these rocks do occur in the Bighorn and Owl Creek Mountains in the north-central part of the state, as well as in the Black Hills in northeastern Wyoming. These rocks record the classic sequence of nearshore sandstones overlain by deeper water shales and limestones laid down as a shallow sea flooded the continent. Fossils of trilobites, brachiopods, and algae are fairly common in the shales and limestones, and vertical burrows (trace fossils) occur in some of the sandstones. |