Ferdig Member of Marias River Formation

Gray and dark gray shale with thin siltstone or sandstone beds at the top. Marine. Thickness as much as 125m (410 ft).
State Montana
Name Ferdig Member of Marias River Formation
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
References

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 Cascade - Chouteau - Golden Valley - Teton - Toole - Wheatland