Cone and Floweree Members of Marias River Formation

Cone Member (Kmc): Calcareous, dark gray shale and thin limestone beds and lenses. Widespread bentonite bed and septarian concretions near base. Shallow marine. Thickness as much as 20 m (66 ft). Floweree Member (Kmfl): Dark gray, noncalcareous shale with interbeds of siltstone. Calcareous concretions and scattered granules of dark gray chert. Shallow marine. Thickness as much as 30 m (98 ft).
State Montana
Name Cone and Floweree Members of Marias River Formation
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Bed, Calcareous)
Minor
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Mudstone > Claystone > Bentonite (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Incidental
Sedimentary > Chemical > Chert (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