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National Geologic Map Database

Geologic Unit: East Fork

Usage:

East Fork Formation (ID*)


Geologic age:

Middle Ordovician*
Ordovician, Late(?)*


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

Forms a belt on west side of area of unmetamorphosed rocks as far south as divide between Hyndman Creek and East Fork of Big Wood River, Blaine Co., central ID. Best exposed on east side of headwaters area of Hyndman Creek, Hailey quadrangle (Westgate and Ross, 1930).


AAPG geologic province:

Snake River basin*
Idaho Mountains province*


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 ([ ]).