|Name||Groat sandstone bed of Pierre Formation|
Sedimentary > Clastic > Sandstone (Bed, Glauconitic)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed)silty shale
Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed)sandy shale
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.