Sedan Formation

Varicolored welded tuff and dark brown conglomerate interbedded with sandstone, conglomeratic sandstone, and dark gray or olive gray mudstone. Nonmarine including mudflow, and marginal marine. Thickness915–1470 m (3,002–4,823 ft).
State Montana
Name Sedan Formation
Geologic age Cretaceous
Lithologic constituents
Sedimentary > Clastic > Conglomerate (Bed)
Igneous > Volcanic (Pyroclastic-tuff)welded tuff
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Clastic > Mixed-clastic > Conglomerate-sandstone (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 Gallatin - Meagher - Park