Includes (ascending): Paine Limestone (raised in rank from member to formation); Middle Canyon Formation (extended into Montana from Idaho); Mission Canyon Limestone; and McKenzie Canyon Limestone (new). These rocks were previously assigned to the Madison and Big Snowy Groups. Is 810 m thick at type and more than 1000 m thick regionally. Consists mostly of limestone, and some chert. Present in northern Tendoy Mountains between McKnight Canyon and Clark Canyon Reservoirs. Rests on Three Forks Formation. Underlies Kibbey Sandstone (reassigned from Big Snowy) of Snowcrest Range Group (new). Fossils: conodonts, corals. Age is Early Mississippian (Kinderhookian and Osagean). Report includes geologic maps, composite section, correlation chart.
Type section (composite): (1) Bull Canyon, sec. 17, T. 11 S., R. 10 W.; and (2) on divide between Bell and McKenzie Canyons, sec. 21, T. 11 S., R. 10 W., Tendoy Mountains, Beaverhead Co., MT. Named from exposures in Tendoy Mountains, Beaverhead Co., MT, Montana folded belt province.

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).