Sixtymile Formation

Usage of Geologic Unit Name:
Sixtymile Formation*
Proterozoic, Late*

Early Proterozoic - about 740 million years (age used by National Park Service; Mathis and Bowman, 2005)
Geologic Province:
Southern Rocky Mountain region*
Plateau sedimentary province*
Areal Extent:
Type Locality:
Type section: Topmost part of Nankoweap Butte and on north side of Sixty Mile Canyon and Awatubi Canyon, lat 36 12' 00" N, long 111 50' 00" W, west of Colorado River, Coconino Co, AZ (Ford, Breed, 1973).
Unit Name History:
First used as Sixty Mile Formation of Chuar Group (Ford and Breed, 1972). Named Sixty Mile Formation, upper formation of Chuar Group of Grand Canyon Supergroup (Ford, Breed, 1973). Adopted as Sixtymile Formation of Chuar Group of Grand Canyon Supergroup; spelling changed to Sixtymile (Elston, 1979). Overview (Elston, 1979; Elston, McKee, 1982). Removed from Chuar Group (Elston, McKee, 1982). Age modified (Elston and McKee, 1982). Paleomagnetics and Overview (Elston, 1989b).

Ford, T.D. and Breed, W.J., 1972, The Chuar Group of the Proterozoic, Grand Canyon, Arizona, IN Geologie du Precambrian, Section 1: International Geological Congress, 24th, Report, no. 1, Montreal, 1972, p. 3-10.

Ford, T.D. and Breed, W.J., 1973, Late Precambrian Chuar Group, Grand Canyon, Arizona: Geological Society of America Bulletin, v. 84, no. 4, p. 1243-1260.

Elston, D.P., 1979, Late Precambrian Sixtymile Formation and orogeny at top of the Grand Canyon Supergroup, northern Arizona: U.S. Geological Survey Professional Paper, 1092, 20 p.

Elston, D.P. and McKee, E.H., 1982, Age and correlation of the late Proterozoic Grand Canyon disturbance, northern Arizona: Geological Society of America Bulletin, v. 93, no. 8, p. 681-699.

Elston, D.P., 1989, Grand Canyon Supergroup, northern Arizona; stratigraphic summary and preliminary paleomagnetic correlations with parts of other North American Proterozoic successions, IN Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Digest, v. 17, p. 259-272.

Ford, T.D., 1990, Grand Canyon Supergroup: Nankoweap Formation, Chuar Group, And Sixtymile Formation. In: Beus, S.S., Morales, M., editors, Grand Canyon Geology, Oxford University Press, New York, p. 49-70.

Mathis, A. and Bowman, C., 2005, What's in a number? Numeric ages for rocks exposed within the Grand Canyon, Part 2: Nature Notes ( Grand Canyon National Park ), v. 21, no. 2, p. 1-5.

Return to Main Page
* show accepted USGS usage.
Note that data on this page contains information that has been partly revised from bibliographic resources available via the National Geologic Map Database GEOLEX:
The URL is:
Last modified: 1/7/2011