Carter Creek through Coberly Formation: Carter Creek, Jens, and Coberly Formations

Carter Creek Formation: Varicolored sandstone, siltstone, and silty mudstone, with subordinate dark shale and lenses of coarse-grained conglomeratic dacitic tuff. Nearshore marine, brackish, and terrestrial. Thickness as much as 2,000 m (6,562 ft). Jens Formation: Dark gray shale, siltstone, siliceous mudstone, volcaniclastic siltstone, and minor fine-grained calcareous sandstone. Marine. Thickness as much as 505 m (1,657 ft). Coberly Formation: Gray limestone and tan, massive sandstone. Intertidal and shallow marine. Thickness as much as 215 m (705 ft).
State Montana
Name Carter Creek through Coberly Formation: Carter Creek, Jens, and Coberly Formations
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Bed, Calcareous)
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed)
Minor
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Mudstone > Shale (Bed)
Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic-tuff)lenses of coarse-grained conglomeratic dacitic tuff
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 Granite - Powell