Two Medicine and Virgelle Formations

Volcaniclastic facies: gray, greenish gray, maroon, and reddish gray volcaniclastic rocks, volcanic flows, and tuff. Fluvial and alluvial plain. Thickness as much as 660 m (2,165 ft).
State Montana
Name Two Medicine and Virgelle Formations
Geologic age Cretaceous
Lithologic constituents
Major
Igneous > Volcanic (Volcaniclastic, Flow, Pyroclastic-tuff)
References

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 Cascade - Lewis and Clark - Teton