Golden Spike Formation

Volcaniclastic sandstone and conglomerate, chert-pebble conglomerate, andesitic lava, andesitic tuff, and limestone. Fluvial, mudflow, and landslide, locally derived from Elkhorn Mountains Volcanics. Thickness as much as 2,700 m (8,858 ft).
State Montana
Name Golden Spike Formation
Geologic age Cretaceous
Lithologic constituents
Major
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Tuffaceous)
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow, Pyroclastic-tuff)
Minor
Sedimentary > Carbonate > Limestone (Bed)
Incidental
Sedimentary > Chemical > Chert (Bed)chert-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 Powell