Two Medicine Formation

Gray and greenish gray volcanic sandstone, siltstone, and mudstone, andesite–pebble conglomerate, and thin beds of very light gray and pink ash-fall tuff. Fluvial and alluvial plain. Thickness as much as 660 m (2,165 ft).
State Montana
Name Two Medicine Formation
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Tuffaceous)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Minor
Igneous > Volcanic (Pyroclastic-tuff)
Sedimentary > Clastic > Conglomerate (Bed)
Igneous > Volcanic > Mafic-volcanic > Andesiteandesite–pebble conglomerate
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 Broadwater - Cascade - Glacier - Lewis and Clark - Pondera - Teton - Toole