Organ Rock Formation Organ Rock Formation The Organ Rock Formation or Organ Rock Shale is a formation within the late Pennsylvanian to early Permian Cutler Group and is deposited across southeastern Utah, northwestern New Mexico, and northeastern Arizona. This formation notably outcrops around Canyonlands National Park, Natural Bridges National Monument, and Monument Valley. The age of the Organ Rock is constrained to the latter half of the Cisuralian Epoch by age dates from overlying and underlying formations. Important early terrestrial vertebrate fossils have been recovered from this formation in northern Arizona, southern Utah, and northern New Mexico. These include the iconic Permian terrestrial
Straight Cliffs Formation is the partial lateral equivalent of the Mancos Shale formation further east. The Straight Cliffs Formation is latest Turonian to early Campanian in age. The stratigraphy of the formation was initially studied for its coal resources and has more recently been studied as an analog for petroleum reservoirs. Consequently, the stratigraphy of the Straight Cliffs has been analyzed in detail. The Straight Cliffs Formation was deposited in the Kaiparowits Basin of the Western Interior Seaway. The basin received sediment from the Mogollon highlands, the Sevier fold-thrust and the Cordilleran volcanic arc. The Mogollon highlands were mountains in central Arizona. The