Vaughn Member of Blackleaf Formation

Black carbonaceous shale, light gray, greenish to pinkish bentonitic to tuffaceous siltstone and porcellanite, tuffaceous, arkosic sandstone, thin coal; conglomerate beds in western Montana. Fluvial and coastal delta plain. Thickness as much as 200 m (656 ft).
State Montana
Name Vaughn Member of Blackleaf Formation
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Siltstone (Bed, Tuffaceous)
Sedimentary > Clastic > Sandstone (Bed, Tuffaceous, Arkosic)
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed, Carbonaceous)
Incidental
Sedimentary > Coal (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Mudstone > Claystone > Bentonite (Bed)bentonitic to tuffaceous siltstone
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