Upper Tertiary sediment or sedimentary rock

Conglomerate, tuffaceous sandstone and siltstone, marlstone, and equivalent sediment and ash beds. Local volcanic flows in southwestern Montana. Includes Sixmile Creek Formation. Dominantly fluvial, alluvial fan, mudflow, and palustrine. Composite thickness for Tsu and Tsm exceeds 4,880 m (16,010 ft).
State Montana
Name Upper Tertiary sediment or sedimentary rock
Geologic age Tertiary
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Tuffaceous)
Sedimentary > Clastic > Siltstone (Tuffaceous)
Sedimentary > Clastic > Conglomerate
Minor
Sedimentary > Carbonate > Marlstone
Incidental
Igneous > Volcanic (Pyroclastic, Flow)ash beds, Local volcanic flows in southwestern Montana
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 Beaverhead - Broadwater - Gallatin - Granite - Jefferson - Madison - Meagher - Missoula - Ravalli - Silver Bow