Generalized stratigraphy after an unpublished NPS flyer on park stratigraphy and modified after Bues, S. S. and Morales, M., 1990, Grand Canyon Geology: New York: Oxford University Press, p. 9.

Please note: The thickness of stratigraphic units are highly variable across the large region encompassed by Grand Canyon National Park. The scale above on this composite section does not reflect this variability. For more detailed thickness of unit descriptions, see:

Billingsley, G. H. and Wellmeyer, J. L., 2003, Geologic map of the Mount Trumbull 30 X 60 quadrangle, Mohave and Coconino Counties, Northwestern Arizona: U.S. Geological Survey Geologic Investigations Series I-2766, map scale 1:100,000; 36 p. pamphlet. Available on-line at: http://pubs.usgs.gov/imap/i2766/.

Billingsley, G. H., 2000, Geologic map of the Grand Canyon 30' x 60' quadrangle, Coconino and Mohave Counties, northwestern Arizona: U.S. Geological Survey Geologic Investigations Series I-2688, map scale 1:100,000. Available on-line at: http://pubs.usgs.gov/imap/i-2688/.

Click here to see photography of Grand Canyon National Park. This includes views along and within the canyon and a collection of historic images along the Colorado River taken by the Powell Expedition of 1872. Website images include both standard photograph and 3D views (as anaglyphs - requiring red-and-cyan 3D viewing glasses).

This view is looking east (upstream) along the Grand Canyon from the Toroweap Overlook area. Massive cliffs of the Redwall Sandstone dominate the canyon at Toroweap.

Stratigraphic unit information is modified from the USGS GeoLex (Lexicon of Geology): http://ngmdb.usgs.gov/Geolex/geolex_qs.html.

Information about the Geologic Time Scale is available here.