Fort Union Formation

No unique unit description on map. Assumed to include undivided Tertiary age members of the Fort Union Formation: Sentinel Butte (Tfsb), Tongue River (Tftr), Linley (Tflc), Ludlow (Tfld), Lebo (Tfle), Ekalaka (Tfe), and Tullock (Tft) members.
State Montana
Name Fort Union Formation
Geologic age Tertiary
Lithologic constituents
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed, Carbonaceous)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Mudstone > Claystone > Bentonite (Bed)
Sedimentary > Coal (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.

NGMDB product
Counties Blaine - Chouteau - Hill