|Name||Quadrant and Amsden Formations|
|Geologic age||Pennsylvanian and Mississippian|
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Chemical > Chert (Bed)
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 - Cascade - Gallatin - Lewis and Clark - Madison - Meagher - Park|