Mowry Formation

Light gray to silvery gray, platy to blocky, siliceous shale and subordinate thin-bedded, gray siltstone or very fine-grained sandstone laminae or beds. Fish scales common in central Montana. Ledge-forming, chert-bearing, fine- to medium-grained sandstone at top throughout west-central Montana. Marine. Thickness 240 m (787 ft).
State Montana
Name Mowry Formation
Geologic age Cretaceous
Lithologic constituents
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Siltstone (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.

NGMDB product
Counties Beaverhead - Big Horn - Carbon - Carter - Cascade - Fergus - Gallatin - Judith Basin - Madison - Musselshell - Petroleum - Stillwater - Yellowstone