|Name||Basalt: includes basalt of several ages in southwestern Montana|
Igneous > Volcanic > Mafic-volcanic > Basalt
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.
|Counties||Beaverhead - Broadwater - Cascade - Gallatin - Jefferson - Lewis and Clark - Madison - Meagher|