Tyler Formation

Cameron Creek Member (upper part of formation):red, purple, and brown mudstone and siltstone, and quartzose sandstone with subordinate gray shale and limestone. Bear Gulch Member (middle part of formation, locally): gray, fossiliferous, platy, argillaceous limestone. Stonehouse Canyon Member (lower part of formation): dark gray, carbonaceous mudstone with lenses of sandstone or conglomeratic sandstone. Fluvial and intertidal. Thickness as much as 180 m (590 ft).
State Montana
Name Tyler Formation
Geologic age Pennsylvanian and Mississippian
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Mudstone (Bed, Carbonaceous)
Sedimentary > Clastic > Siltstone (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed, Lens)
Sedimentary > Clastic > Mixed-clastic > Conglomerate-sandstone (Lens)
Sedimentary > Clastic > Mudstone > Shale (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 Fergus - Golden Valley