Stillwater complex

Layered ultramafic and mafic rocks from peridotite and pyroxenite at the base (ultramafic series) to gabbro and anorthosite in the upper part (banded series). Maximum exposed thickness in the Beartooth Mountains is about 6,700 m (22,000 ft).
State Montana
Name Stillwater complex
Geologic age Archean
Lithologic constituents

Vuke, S.M., Porter, K.W., Lonn, J.D., and Lopez, D.A., 2007, Geologic Map of Montana - Compact Disc: Montana Bureau of Mines and Geology: Geologic Map 62-C, 73 p., 2 sheets, scale 1:500,000. This map was digitized in 2012 as a result of a contract between the U.S. Geological Survey and the Montana Bureau of Mines and Geology.

NGMDB product
Counties Park - Stillwater - Sweet Grass