Paleontology and geology
North Dakota was near the equator during the Permian, and shallow seas covered the state. These seas became progressively shallower, and at times, dry land was exposed. Carbonates, evaporites, and red beds were deposited. Brachiopods, bryozoans, crinoids, and fusulinids have been recovered from rocks of Permian age in North Dakota. These rocks are not exposed at the surface, but information about them comes from drill cores.