During Paleozoic and Mesozoic time the Kaiparowits and Black Mesa basins (Colorado Plateau) occupied a northwest-trending structural trough across the shelf between the Cordilleran geosyncline and the transcontinental arch. Periodic sags allowed deposition of Cambrian, Devonian, Mississippian, Pennsylvanian, and Permian marine sediments. Upper Permian red beds and eolian sandstone are overlain by transgressive-phase carbonates; Mesozoic sediments consist mainly of red beds and eolian sandstone. Complex Permian and Mesozoic facies changes and abrupt stratigraphic terminations may prove to be traps for oil accumulation. The bibliography is comprehensive.