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 fossils from the Straight Cliffs Formation document a diverse assemblage of therian mammals. The Tibbet Canyon Member contains sharks’ teeth from marine deposits rare mammal fossils from deltaic deposits. Recovered fossils include sharks, rays, lepisosteid fishes, crocodyliforms, and fragmentary marsupial mammal teeth. The Smoky Hollow Member also contains a variety of sharks, amphibians, reptiles, snakes, crocodyliforms, and dinosaurs. The member also contains multituberculate and marsupial mammals. The John Henry Member contains more brackish and marine fauna, as well as mammals and other terrestrial species which are less common. The Drip Tank Member is primarily fluvial and consequently only water worn