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
Fossil Beach (Sedbury Cliffs) examples in the bulk of the mudstone: the cliffs are easily weathered, with parts subject to notable expansion and contraction, Sedbury Cliffs and the foreshore contain similar geological layering to the more famous and visible Aust Cliff the on the opposite site of the River Severn. However, at Sedbury the cliffs are wooded at the top and overgrown with bushes and trees at the base, with fallen blocks and old trunks amongst them. Farther along the beach from the grass, sandstone blocks become more common. The highest rock layer is the brown rocks of the Blue Lias formation, which was