Grand Canyon’s Three Sets of Rocks

Photo of Colorado River and the cliffs and buttes of Grand Canyon.
A view of Grand Canyon showing all three sets of Grand Canyon rocks.

NPS photo.


Beginning with John Wesley Powell, the geologist who led the pioneering river expedition through Grand Canyon in 1869, geologists have recognized three main packages of rocks exposed in Grand Canyon:

  • The Vishnu Basement Rocks: The igneous and metamorphic rocks of the three Granite Gorges.

  • The Grand Canyon Supergroup: Tilted, mostly sedimentary rocks.

  • The Layered Paleozoic Rocks: The flat-lying strata in the upper two-thirds of the canyon.

The informal term “set” is used to refer to Powell’s three main packages of rocks. This term is not part of the formal stratigraphic naming system of supergroups, groups, formations, and members, but is closest to the supergroup level and is convenient and very visual for Grand Canyon.
Within these three main groupings of rocks are:

  • Six packages at the group stratigraphic level;

  • 35 individual formations;

  • At 53 least members.

A total of more than 180 stratigraphic units have been named in Grand Canyon Park, including Paleozoic units exposed in places in the western Grand Canyon, Mesozoic rocks, and Cenozoic deposits that weren’t included in the three main sets of rocks.

The 3 Sets of Rocks


Rock Types


Age (Ma)

Layered Paleozoic Rocks

Horizontal sedimentary rock layers

Low coastal plain and shallow seas of the continental shelf along the proto-Pacific coast

Paleozoic Era 270–530

Grand Canyon Supergroup

Tilted sedimentary and igneous rock layers

Rivers and shallow seas far from the active plate margin as the supercontinent Rodinia assembled (Unkar Group) and rifted apart (Chuar Group)

Meso- and Neoproterozoic Eras (Precambrian) 729–1255

Vishnu Basement Rocks

Metamorphic and igneous rocks with vertical folds and foliation

Originally in volcanic island chains that collided with ancestral North America to form the southwest United States; rocks were metamorphosed and invaded by magmas in the deep crust.

Paleo- and Mesoproterozoic Eras (Precambrian )1375–1840

Table 1.
Ma = mega annum = million years ago

Diagram showing stratigraphic column of Grand Canyon rocks.
Figure 24. Stratigraphic column of rocks of the Grand Canyon region showing the three sets of rocks and major unconformities: Great Nonconformity (white line), Great
Angular Unconformity (red line) and Great Unconformity (black line). Fm = Formation; Ss = Sandstone; Ls = Limestone.

Vishnu Basement Rocks

The Vishnu Basement Rocks consist of the ancient metamorphic rocks that formed and were intruded by igneous rocks in the deep crust nearly 2,000 million (2 billion) years ago. They have undetermined thickness because the original sedimentary succession has been intensely folded so the originally horizontal layering is now subvertical.

Grand Canyon Supergroup

The Grand Canyon Supergroup is only exposed in the eastern Grand Canyon. They are late Precambrian sedimentary and volcanic rocks predominantly deposited in rift basins from about 729 to 1,255 million years ago. These strata are about 12,000 feet (3,600 m) thick.

Layered Paleozoic Rocks

The Layered Paleozoic include the flat-lying sedimentary rocks in the “stair-step” upper canyon walls throughout Grand Canyon. These strata are 3,000–5,000 feet (900–1,500 m) thick. The layers record many changing environments from shallow oceans to large sand dunefields, and the history of life on Earth about 530 to 270 million years ago.

Learn More

Tiny image of the cover of a report titled Telling Time at Grand Canyon National Park.

To learn more about the age of Grand Canyon’s rocks, please see:

Karlstrom, K., L. Crossey, A. Mathis, and C. Bowman. 2021. Telling time at Grand Canyon National Park: 2020 update. Natural Resource Report NPS/GRCA/NRR—2021/2246. National Park Service, Fort Collins, Colorado. [IRMA Portal]

Photos and Illustrations

Part of a series of articles titled Telling Time at Grand Canyon National Park.

Grand Canyon National Park

Last updated: March 1, 2024