National Geologic Map Database

Geologic Unit: Grand Prize


Grand Prize Formation of Sun Valley Group (ID*)

Geologic age:

Middle Pennsylvanian to Early Permian (Desmoinesian to Leonardian)*

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

North slope, Pole Creek Canyon at confluence with Grand Prize Creek, Horton Peak 7.5-min quadrangle, Custer Co., ID (Hall, 1985).
Supplemental reference section (composite): at Fourth of July Creek, Custer Co., ID, within Obsidian and Washington Peak quadrangles. Basal 500 m measured in Strawberry Basin, north of Blackman Peak at 9,800 to 10,111 ft elevation; 500 to 2,500 m interval measured on ridge north of Fourth of July Creek at 7,800 to 9,200 ft elevation (Mahoney and Sengebush, 1988).
Reference section (composite): member 1 in Strawberry basin, Lat. 44 deg. 04 min. 28 sec. N., Long. 114 deg. 39 min. 32 sec. N., 9,800 to 10,111 ft elevation, north of Blackman Peak, Blaine Co., ID; members 2, 3, 4 are north of Fourth of July Creek, Lat. 44 deg. 03 min. 18 sec. N., Long. 114 deg. 43 min. 48 sec. W. Other reference section for members 2, 3, 4 on ridge south of Champion Lakes.

AAPG geologic province:

Idaho Mountains province*
Snake River 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 ([ ]).