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Eagle sandstone

Eagle sandstone: sandstone and shaly sandstone with lignite beds in basal part of upper unit (Keu). The Virgelle sandstone member (Kvi) at base is distinguished where possible. Near Yellowstone National Park rocks incorrectly called Laramide in early reports and now regarded as roughly equivalent to the Eagle sandstone are tentatively mapped as Eagle sandstone. Gray to buff massive cliff-forming sandstone with iron stained concretions in the upper part. In western Montana the Virgelle is a formation and in central Montana it is the basal member of the Eagle sandstone.
State Montana
Name Eagle sandstone
Geologic age Phanerozoic | Mesozoic | Cretaceous-Late
Comments The map unit Kvi refers to the Virgille sandstone member of the Eagle sandstone formation. In western Montana the Virgelle is a formation and in central Montana it is the basal member of the Eagle sandstone.
Primary rock type sandstone
Secondary rock type siltstone
Other rock types
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Siltstone (Bed)
Map references
Ross, P.R., Andrews, D.A., and Witkind, I.J., 1955, Geologic map of Montana: U.S. Geological Survey, 2 sheets, scale 1:500,000.
Unit references
Roberts, A.E., 1972, Cretaceous and early Tertiary depositional and tectonic history of the Livingston area, southwestern Montana, in Geology of the Livingston area, southwestern Montana: U.S. Geological Survey Professional Paper 526-C, p. C1
du Bray, E.A., Elliott, J.E., Wilson, A.B., Van Gosen, B.S., and Rosenberg, L.A., 1993, Geologic map of the Big Timber Stock and vicinity, southern Crazy Mountains, Sweet Grass and Park Counties, south-central Montana: U.S. Geological Survey Miscellaneou
Fraser, G.D., Waldrop, H.A. and Hyden, H.J., 1969, Geology of the Gardiner area, Park County, Montana: U.S. Geological Survey Bulletin 1277, 118 p.
Counties Cascade - Chouteau - Glacier - Hill - Lewis and Clark - Liberty - Teton - Toole