The Morrison Formation is composed of three members (listed from youngest to oldest): Brushy Basin, Salt Wash and Tidwell. Each has different characteristics due to changes in the depositional environment. This layer does not occur in Canyonlands.
Late Jurassic (144 to 208 million years ago)
Varied between river, tidal flat and shallow marine
Brushy Basin: multicolored Bentonite clays (volcanic ash)
Salt Wash: Light-colored, ledge-forming sandstone.
Tidwell: red marine sandstones frequently containing chert.
The Salt Wash Member is a source of Uranium which was mined throughout the Moab area. Dinosaur tracks and fossils also appear in the Morrison Formation.
Visible in the northern parts of Arches (Salt Valley) and along Highway 191 north of Moab.