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National Geologic Map Database

Geologic Unit: Cannonball

Usage:

Cannonball Member of Fort Union Formation (ND*,SD*)
Cannonball Formation of Fort Union Group (ND,SD)


Geologic age:

early Tertiary (Paleocene)*


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

[Type area:] in bluffs of Cannonball River, south of town of Elgin, in T. 132 and 133 N., R. 88 W., [Elgin 30- x 60-min quadrangle, Grant Co.], southern ND (Lloyd, 1914).


AAPG geologic province:

Sioux uplift*
Williston basin*


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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 ([ ]).