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List of Grand Canyon Rock Layers
What is Grand Canyon Stratigraphy?
Kaibab Formation
Toroweap Formation
Coconino Sandstone
Hermit Formation
Supai Group
Redwall Limestone
Tonto Group
Muav Limestone
Bright Angel Shale
Tapeats Sandstone
Vishnu Complex
Bright Angel Shale
Cambrian Period, 510 Million Years Old, 325 Feet Thick
Forms the broad greenish slope below the Muav and Redwall
The Bright Angel Shale consists mostly of shaly green mudstones with lesser amounts of fine-grained dark sandstones
and dolomites.
Most of the formation is a sediment-covered slope or platform (called the Tonto Platform) broken by low sandstone ledges. Fossils of the
Bright Angel include 47 species of trilobites, inarticulate brachiopods, and primitive mollusks. These
are found in the green shales
and the thin fine-grained sandstones. Tracks, trails, and burrows are also common.
Here is a close view of the upper Bright Angel Shale as seen along the Kaibab Trail. In the right foreground
you can see the thin-bedded nature of the shale and its greenish color from the mineral glauconite. Glauconite is known
only from ocean sediments. This proves, with the marine fossils, that the Bright Angel Shale formed in a marine environment.