Madison Group, Darby Formation, Three Forks and Jefferson Formations

Madison Limestone or Group (Thrust Belt, North Wyoming and Northern Yellowstone area) - Group includes Mission Canyon Limestone (blue-gray massive limestone and dolomite), underlain by Lodgepole Limestone (gray cherty limestone and dolomite). Darby Formation (Thrust Belt and North Wyoming) - Yellow and greenish-gray shale and dolomitic siltstone underlain by fetid brown dolomite and limestone. Three Forks Formation (Northern Yellowstone area) - Pink, yellow, and green dolomitic siltstone and shale. Jefferson Formation (Northern Yellowstone area) - Massive siliceous dolomite.
State Wyoming
Name Madison Group, Darby Formation, Three Forks and Jefferson Formations
Geologic age Upper Devonian-Upper Mississippian
Lithologic constituents
Major
Sedimentary > Carbonate > Dolostone
Sedimentary > Carbonate > Limestone
Minor
Sedimentary > Clastic > Siltstone
Sedimentary > Clastic > Mudstone > Shale
References
NGMDB product
Counties Big Horn - Fremont - Hot Springs - Johnson - Lincoln - Park - Sheridan - Sublette - Teton - Washakie