Medicine Lodge Creek [Member] of Tensleep Formation. The lower, marine unit of the Tensleep Formation in the Big Horn and Wind River basins, Wyoming, is here named the Medicine Lodge Creek Member. Consists of white to tan and pink, subangular to subrounded, fine-grained, quartzose sandstone, extensively cemented by calcite and dolomite, and numerous gray-green to white, fossiliferous limestone and dolomite beds intercalated with marine shale beds. Underlies the Hyatt Ranch Member (new name) of the Tensleep with angular unconformity. Correlates with the middle member of the Minnelusa Formation. Thickness ranges from 150 to 200 feet. Age is Middle Pennsylvanian (Desmoinesian) based on marine megafossils and fusulinids.
Type locality: exposures in the canyon of Medicine Lodge Creek, in center T. 50 N., R. 89 W., [Hyatt Ranch 7.5-min quadrangle], Big Horn Co., central northern WY.

[Rank term is lowercased by author. Name is listed as a formal unit in US geologic names lexicon (USGS Bull. 1565, p. 197, 1991) and, in accordance with nomenclature guidelines (ASCN, 1961, 1970; NACSN, 1983), the rank term is capitalized. However, it is implied from GNU records (USGS DDS-6; Denver GNULEX, September 10, 1992) that the Medicine Lodge Creek is informal. No explanation is provided for this change in classification from what is listed in the lexicon (USGS Bull. 1565). Until we are informed otherwise, we will retain the Medicine Lodge Creek as a formal member of the Tensleep.]

Source: US geologic names lexicon (USGS Bull. 1565, p. 197).