Jurassic and Triassic rocks, undifferentiated (MTJTR;0)

State	Montana
Name	Jurassic and Triassic rocks, undifferentiated
Geologic age	Phanerozoic \| Mesozoic \| Triassic Jurassic
Original map label	JTR
Primary rock type	fine-grained mixed clastic
Secondary rock type	limestone
Other rock types	medium-grained mixed clastic; evaporite
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed) Minor Sedimentary > Clastic > Mixed-clastic > Conglomerate-sandstone (Bed) Incidental Sedimentary > Chemical > Evaporite > Gypsum (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	Kohrt, P.B., 1991, Alkalic rocks of the Judith Mountains, central Montana, in Baker, D.W., and Berg, R.B., eds., Guidebook of the Central Montana Alkalic Province--Geology, ore deposits and origin: Montana Bureau of Mines and Geology Special Publication Wilson, A.B., and Elliott, J.E., 1997, Geologic maps of western and northern parts of Gallatin National Forest, south-central Montana: U.S. Geological Survey Geologic Investigations Series Map I-2584, 2 sheets, scale 1:126,720. [http://pubs.er.usgs.gov/publication/i2584] Kellogg, K.S., and Williams, V.S., 2000, Geologic map of the Ennis 30' x 60' quadrangle, Madison and Gallatin Counties, Montana, Park County, Wyoming: U.S. Geological Survey Miscellaneous Geologic Investigations Series Map I-2690, scale 1:100,000. [http://pubs.er.usgs.gov/publication/i2690]
Geographic coverage	Madison