~175-170 million years ago
The Temple Cap Formation in Zion consists of sandstone and a layer of mudstone formed by coastal sand dunes and tidal flats during the incursion of a shallow inland sea.
The Temple Cap Formation preserves the remains of a complicated coastal environment which followed the vast dune field of the Navajo Sandstone.
A shallow sea (specifically the Sundance Sea) encroached into the area, leaving in its wake a wide-range of rock types. These range from red mudstones deposited on a tidal flat, to sandstones deposited by small wind-blown, or aeolian, dunes left on sandy beaches, to limestones deposited when the area was briefly under sea level.
Cross-bedding from ancient wind-blown sand dunes is found in the Temple Cap, as seen in this outcrop along the East Rim Trail. The Temple Cap Formation is also encountered on the high parts of the West Rim Trail (below, on top of the Navajo Sandstone).
No fossil material from the Temple Cap Formation is known in Zion National Park, though this may be related to the remote nature of the outcrops; in Zion the Temple Cap tends to be easy to spot, but very difficult to get to.
The Temple Cap gets its name from the East Temple (shown) and West Temple, where it is the small cliff capping these dramatic features.
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Last updated: June 13, 2015