Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Montana
|Geologic age||Proterozoic | Mesoproterozoic|
|Original map label||pCr|
|Comments||The term "Ravalli Group" is an obsolete nomenclature, now replaced on more modern geologic maps by individually mapped formations. Appears to include the Burke Formation, Grinnell Formation, Spokane Formation, Revett Formation, St. Regis Formation, and perhaps the Empire Formation (see USGS Map I-2267).|
|Primary rock type||meta-argillite|
|Secondary rock type||quartzite|
|Other rock types|
Metamorphic > Metasedimentary > Metaclastic > Argillite (Greenschist)
Metamorphic > Metasedimentary > Metaclastic > Quartzite (Greenschist)
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.
Lewis, R.S., 1998, Preliminary geologic map of the Butte 1° x 2° quadrangle: Montana Bureau of Mines and Geology Open File Report 363, 16 p, scale 1:250,000.
|Geographic coverage||Deer Lodge - Flathead - Granite - Lake - Lincoln - Mineral - Missoula - Powell - Ravalli - Sanders|
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