Grand Canyon Geology

Grand Canyon Geology

The Kaibab Plateau and other uplifted areas in the four corners area of Northern Arizona and southern Utah, Colorado and northwestern New Mexico were formed between 30-60 million years ago during the Laramide Revolution. This happened about the same time as the Rockies were being formed. The uplift deflected the course of the Colorado River and along with a rising land mass in Eastern Arizona, created the conditions that formed a massive lake. At the same time on the western edges of the Kaibab Plateau smaller drainage systems were converging into one massive system which eventually caused the erosion of the Grand Canyon.

Along with the massive uplift and the conditions it created, the massive erosion of the Grand Canyon continues from landslides, water from melting snows, massive volumes of rain from violent summer thunderstorms that drain into the canyons from the sides and from other typical agents of erosion like: wind, ice and frost.

The following table details the geological layers in the Grand Canyon. We’ve included the layer name, age, depth, color, Geologic Period and Geologic Era in the table.

Grand Canyon Geology - Primary Rock layers

Rock Formation Feet Thick Color Geologic Period Geologic Era Notes
Kaibab Limestone 325′ Grey-White Permian Paleozic Yaki Point 7,260 feet. Kaibab Limestone is called the bathtub ring. It is a greyish white in color. Fossils in the Kaibab Limestone layer contain brachiopods, mollusks, sea lillies and coral.
Toroweap Formation 350′ Red and Buff Permian Paleozic This layer mimics the Kaibab Limesone layer but it is darker in color and ranges from yellow to grey and contains sea deposits-shells, corals and sponges.
Coconino Sandstone 350′ Buff Permian Paleozic This layer contains pure quartz Dune Sands-and contains fossils of tracks of primitive reptiles and amphibians. It ranges from white to cream colored.
Hermit Shale 350′ Red Permian Paleozic This layer contains fresh water deposits-tracks, primitive cone-bearing plants, ferns, conifers, insect wings, sun-cracked silts. It is a deep rust colored red.
Supai Formation (Sandstone) 225′ Red Pennsylvanian Paleozic Flood-plain deposits-plants, tracks of land animals
Redwall Limestone 450′-500′ Blue-gray | Stained Red Mississipian Paleozic Sea deposits-shells, corals
Temple Butte Limestone 36′ Purplish Devonian Paleozic Shifts from sand to limestone, represents estuary channels (unconformity)
Muav Limestone 100′ Gray Cambrian Paleozic This layer is part of the Tonto Group and is composed mostly of limestone that is separated by beds of sandstone and shale and is much thicker in the western areas of the Grand Canyon than it is in the east. It is grey in color and it does not contain many fossils with the exception of some trilobites and brachiopods.
Bright Angel Shale 450′-640′ Greenish-Gray Cambrian Paleozic This layer is part of the Tonto group and is made up of mudstone shale. It is also interbedded with small sections of sandstone and sandy limestone. Fossils in the Bright Angel Shale layer consist of marine animals such as trilobites and brachiopods.
Tapeats Sandstone 225′ Dark Brown Cambrian Paleozic This layer is part of the Tonto group and is composed of medium-grained and coarse-grained sandstone. This layer contains ripple marks that were formed by ocean waves from an early Cambrian sea. You will find fossils of trilobites. brachiopods, and trilobite trails in this layer.
Zoroaster Granite   Weather to Dark Gray, Brownish-Black and Black PreCambrian Proterzoic One of the oldest rocks exposed in the Grand Canyon. This layer along with the Vishnu Schist were the foundations of an old mountain range the size of the Rockies. See the formation note below for Vishnu Schist as this layer was formed the same way.
Vishnu Schist   Weather to Dark Gray, Brownish-Black and Black PreCambrian Proterzoic This layer along with the Zoroaster Granite is one of the oldest exposed layers in the Grand Canyon. This layer was formed from original sediments of sandstone shale and limestone. The original was metaporphosed and combined with metamorphosed lava flows that helped to form the Vishnu Schist.

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