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National Geologic Map Database

Geologic Unit: Castle Reef

Usage:

Castle Reef Formation of Madison Group (MT*)
Castle Reef Dolomite of Madison Group (MT*)


Subunits:

(alphabetical) --all in MT: Dupuyer Creek unit* (informal), Gateway Pass unit* (informal), Sun River Member.


Geologic age:

Middle Mississippian (Visean; late Osagean to Meramecian)*


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

Type section: north of Diversion Lake, on ridge that forms east side of Hannan Gulch, Teton Co., MT (Mudge and others, 1962).
Principal reference: in sec. 21, T. 27 N., R. 9 W., Teton Co., MT, Teton Co., MT (Nichols, 1984).


AAPG geologic province:

Sweetgrass arch*
Montana folded belt*


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 ([ ]).