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National Geologic Map Database

Geologic Unit: Tonto

Usage:

Tonto Group (AZ*)


Subunits:

(alphabetical) --all in AZ*: Bright Angel Shale, Muav Limestone, Tapeats Sandstone.


Geologic age:

Cambrian, Early*
Cambrian, Middle*


Type section, locality, area and/or origin of name:

Not stated. Tonto Group floors the valleys that contain the headwaters of the Colorado and of the Verde and Tonto Creek, tributaries of the Salt River [Coconino and Mohave Cos.], northwestern AZ (Gilbert, 1875).


AAPG geologic province:

Plateau sedimentary province*


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).