Stratigraphy and Origin of the Triassic Moenkopi Formation and Related Strata in the Colorado Plateau Region : prepared on behalf of the U.S. Atomic Energy Commission : description of the stratigraphic succession, sedimentary facies, petrology, primary sedimentary structures, fossils, and depositional environments of the Moenkopi Formation and regionally correlative strata / by J.H. Stewart, F.G. Poole, and R.F. Wilson ; with a section on Sedimentary petrology by R.A. Cadigan