~270 million years ago
The Kaibab Formation consists of marine limestone and siltstone that was deposited in a shallow tropical sea and coastal flats on the west coast of the supercontinent Pangaea. Fossils found are of organisms that lived in the Permian seas, including brachiopods (which resemble clams), ammonites (shelled cephalopods which resembled the modern Nautilus), bryozoans (filter-feeding organisms similar to coral), crinoids (marine animals also known as sea lilies), and trilobites.
Within Zion, the Kaibab Formation is exposed only in a small corner of the Kolob Canyons section of the park. However, the Kaibab outcrops along the Hurricane Fault south of Kolob along I-15, and south of the park in the Virgin River canyon.
The older Toroweap Formation is partially exposed directly below the Kaibab, but the area is too small to appear on the park geologic map.
The Kaibab Formation is well-known and easily visible at both the north and south rims of the Grand Canyon, where it forms the resistant cap rock of the canyon. The Kaibab limestone forms the uppermost cliffs of the canyon, with the slopes and ledges of the Toroweap formation below. Thus, the oldest rocks exposed at Zion are the youngest sedimentary layers at the Grand Canyon.
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Last updated: June 13, 2015