to 27 m) thick white to yellowish gray cliff-forming Shinarump Member of the Chinle Formation. The Shinarump is made of low to high-angle cross-stratified and friable fine to coarse-grained sandstone interbedded with conglomerate. Good outcrops of the Shinarump are found near the park's west entrance capping such features as the Egyptian Temple and Chimney Rock while all traces of this member are absent further east. Members above the Shinarump tend to be finer due to the slower speed of the streams that deposited them. A river system then migrated northward and transitioned into either a large lake or marsh. As this occurred, bentonite-rich clay (formed in part from volcanic ash erupted from nearby volcanoes) and clayey cross-bedded sand with some interbeds and lenses of lime ooze were laid down. This eventually became the light purplish-gray claystone, sandstone, and carbonate rock of the Chinle's Monitor Butte Member. Burrows that measure 5 inches (13 cm) in diameter and 5 feet (1.5 m) long were excavated by lungfish into the Monitor Butte. This member easily stands out in the lower to middle slopes of the Waterpocket Fold's west face in such places as The Castle and along the cliff's just north of State Route 24 as it enters the park. Very sinuous rivers covered the area in later Triassic time, forming the sediments of the Chinle's Petrified Forest Member. The Petrified Forest is composed of reddish-orange bentonite-rich cross-bedded siltstones and clayey fine-grained quartz sandstones. The lower part of this member forms gullied slopes and the upper part forms a resistant cliff called the 'Capitol Reef bed.' Carbonate nodules along with fossil bivalves, coprolites, marine snails, lungfish toothplates, and tetrapods are found in the Petrified Forest Member. Deposition from a series of lakes then dominate the geologic record, resulting in the locally 150 to 200 foot (45 to 60 m) thick Owl Rock Member of the Chinle. The Owl Rock is made of purple and orange mudstones, fine-grained sandstones and siltstones with interbedded 1 to 10 foot (30 to 300 cm) thick green to mottled pink micritic and knobby limestone. Fossilized desiccation mudcracks that are up to 4 inches (10 cm) wide and 3 feet (1 m) deep are found at the very top of the Owl Rock (they were later filled with sand from the overlying Wingate Sandstone). Also found in the Owl Rock are trace fossils of cylindrical burrows and fossils of