Pilgrim through Meagher Formation: Pilgrim, Park, and Meagher Formations

Pilgrim Formation: Gray, commonly mottled limestone that may contain intraformational limestone conglomerate. Shallow marine. Thickness as much as 180 m (590 ft). Park Formation: Grayish green, fissile, micaceous shale with a few thin beds of calcareous sandstone and thin, gray limestone. Local arkose beds. Offshore marine. Thickness as much as 310 m (1,017 ft). Meagher Formation: Gray to bluish gray limestone and dolomitic limestone, locally mottled and with intraformational conglomerate beds. Shallow marine. Thickness as much as 300 m (984 ft).
State Montana
Name Pilgrim through Meagher Formation: Pilgrim, Park, and Meagher Formations
Geologic age Cambrian
Lithologic constituents
Major
Sedimentary > Clastic > Mudstone > Shale (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed, Calcareous, Arkosic)
Incidental
Sedimentary > Carbonate > Dolostone (Bed)Dolomitic limestone
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 - Cascade - Madison - Meagher