Granite Peak
       7 ½’ quadrangle: Granite Peak, MT
       Park County
       Custer National Forest, Absaroka-Beartooth Wilderness
       Beartooth Range, Rocky Mountains
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Metamorphic (metamorphosed igneous)
12,799 ft (3,901 m)

Location of Granite Peak, south-central Montana

Bedrock: Gneiss

Archean

Predominantly granitic gneiss and migmatite, commonly with alternating layers of more felsic and more mafic gneiss. The Absaroka Range, by contrast, is made largely of volcanic rocks. The gneiss contains inclusions of metamorphosed country rocks. Northwest-trending mafic dikes traverse Granite Peak’s southwest slope.

Surficial Geology: Alpine glaciers have carved cirques into Granite Peak and the surrounding mountains, producing dramatic scenery. The main ridge is an arête between cirques to the northeast (Granite Glacier and Avalanche Lake) and to the southwest (Sky Top Glacier and Sky Top Lakes). A spur arête leads east to Tempest Mountain. Granite Peak lies at the western edge of Froze to Death Plateau, which gradually decreases in elevation from more than 12,000 feet to 10,800 at Saddleback Mountain.

Soil Series: No soil survey has been published for Park County. Alpine tundra with no trees makes for a very slow rate of soil generation in the Beartooths, in contrast to the Absarokas.

Selected References:

• VanGosen, B.S. and others, 1993, Generalized geologic map of the Absaroka-Beartooth Study Area, south-central Montana: U.S. Geological Survey Open File Report 93-207, 1:126,700. Also published as Miscellaneous Field Studies Map MF-2338, which is available on-line at http://infotrek.er.usgs.gov/pubs/

Other suggested sources of information:

• Glossary: http://www2.nature.nps.gov/geology/usgsnps/misc/glossaryAtoC.html
• Time scale: http://www.ucmp.berkeley.edu/help/timeform.html
• Montana Bureau of Mines and Geology: http://www.mbmg.mtech.edu/
• Beartooth Wilderness: http://www.wilderness.net/index.cfm?fuse=NWPS&sec=wildView&WID=1