Named as the upper member of Manitou formation (revised) in the Piceance basin, Garfield Co, CO. Type section is in the walls of Tie Gulch at east end of U.S. Hwy 6 bridge over Tie Gulch, which enters Glenwood Canyon near center of sec 15, T5S, R87W. Is composed of thin-, thick-bedded to massive, gray, fine to very fine grained dolomite. On South Fork, it has a flat-pebble conglomerate at base. Is 47.7 ft thick in Glenwood Canyon where it overlies the Dead Horse conglomerate member (new) of the Manitou and underlies the Parting member of the Chaffee formation. Has thin stringers of yellow chert on many surfaces. Traces of glauconite. No fossils found. Is one of the most readily recognized units on White River plateau. Cross section. Measured section. Assigned to the Early Ordovician.

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

Name Horseshoe Mountain Group applied to rocks of the Sauk sequence in central CO of Late Cambrian and Early Ordovician age. In its northwest province near Glenwood Springs, Garfield Co in the Piceance basin, the group is divided into the Sawatch Sandstone, Dotsero Formation (and its Glenwood Canyon and Clinetop Members), and Manitou Limestone (and its Deadhorse and Tie Gulch Members). In its southeast province--near Salida, Gunnison Co in the Piceance basin, Colorado Springs, El Paso CO in the Denver basin, and Fairplay, Park Co in the South Park basin--the group is divided into the Sawatch Sandstone, Peerless Formation, and Manitou Limestone (and its Helena Canyon, Ptarmigan (provisional), and Fairplay (provisional) Members). The group is named for exposures on Horseshoe Mountain (the type section) near Fairplay in Park Co. Rocks of the group include conglomerate, sandstone, shale, limestone, and dolomite. Correlation chart. Thickness of group at type (southeast facies--sec. 12, T. 10 S., R. 79 W.) is 352 ft: Manitou, 167 ft; Peerless, 35 ft; and Sawatch, 150 ft. Thickness of group in northwest facies (sec. 15, T. 5 S., R. 87 W.) is 772 ft: Manitou, 156 ft; Dotsero, 96 ft; and Sawatch, 520 ft.

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