[Credited to G.H. Eldridge, "Description of the sedimentary formations" section.] Sawatch quartzite. Lowest sedimentary series in region. Lower division consists of 50 to 200 feet of white quartzite with a persistent conglomerate of pure white quartz at base. Upper division consists of 130 to 180 feet of red ferruginous and somewhat calcareous sandstone composed chiefly of quartz and feldspar with small amount of mica. A green glauconitic mineral occurs in both divisions but more abundantly in upper division, which also contains a few fossils of Potsdam type. The upper division is absent at head of Taylor Creek. The Sawatch rests on Archean granite and gneiss and is overlain by Yule limestone. [Age is Late Cambrian.]
Named from persistent occurrence around flanks of Sawatch Range, [Pitkin Co., western central CO].

Source: US geologic names lexicon (USGS Bull. 896, p. 1936).

The upper red sandy and shaly beds of Sawatch quartzite are in some areas known as "transition shales" and "red cast beds." In Leadville region, they have been named Peerless shale member. [See Behre 1932 (Colorado Sci. Proc., v. 13, no. 3, p. 58) entry under Peerless.]

Source: US geologic names lexicon (USGS Bull. 896, p. 1936).

Recognized in cliffs in the valley of the Eagle River and on dip slopes on flank of Sawatch Range, Eagle Co, CO in Eagle basin where it is a unit about 185 ft thick beneath the Peerless formation. Thins northeast and east from Pando. Rests on a smooth peneplain surface cut over pre-Cambrian rocks. Assigned to the Cambrian. Brachiopod DICELLOMUS identified.

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

Sawatch quartzite. Described along Front Range where it is about 50 feet thick, underlies Ute Pass dolomite (new); overlies Precambrian granite. [Age is Late Cambrian.]

Source: US geologic names lexicon (USGS Bull. 1200, p. 3483-3484).

Pg. 892 (fig. 2), 894, 896, 897. Sawatch quartzite. In White River Plateau, underlies Glenwood Canyon member (new) of Dotsero formation (redefined). [Age is Late Cambrian.]

Source: US geologic names lexicon (USGS Bull. 1200, p. 3483-3484).

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).

Revised in that a 0-100 ft thick quartz arenite and dolomite unit formerly assigned to Sawatch Quartzite removed from Sawatch and named Deadmans Gulch Formation. The new formation which occurs with the Sawatch in central CO in western Gunnison Co,, Piceance basin, Park Co, South Park basin, eastern Eagle, eastern Pitkin, southern Summit, Lake Co, and northern Chaffee Co, Eagle basin, was deposited concurrently with the Peerless Formation. Type section designated as the measured section in Deadmans Gulch, sec 14, T14S, R84W, Gunnison Co, CO in the Piceance basin. Described at type as a 127.4 ft thick, orange to white quartz arenite, and one 3 ft thick bed of conglomerate. The arenite beds may be dolomitic and calcareous, very slightly feldspathic to feldspathic, poorly, moderately to well sorted, fine-medium-, to very coarse grained, subangular, in thin layers to massive bedded, cross-bedded. One bed forms massive cliffs. Conglomerate has quartz pebbles in a matrix of coarse-grained, poorly sorted quartz. Cross sections. Late Cambrian age.

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

Sawatch revised in that it is assigned to the newly named Horseshoe Mountain Group as the basal formation at Salida, Gunnison Co, CO in the Piceance basin; Colorado Springs, El Paso Co, CO in the Denver basin; and Fairplay, Park Co, CO in the South Park basin. Correlation chart. Age not discussed. [Same information presented in Gerhard, 1972, Colorado School of Mines Quarterly, v. 67, no. 4, p. 1-36.]

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

Pg. 12, geologic time scale (inside front cover). Sawatch Quartzite (Cambrian). Sample from altered quartz latite porphyry below Sawatch Quartzite, in outcrop at right-angle bend in Eagle River, south end of Camp Hale, Lat. 39 deg. 26 min. N., Long. 106 deg. 19 min. W., Pando quadrangle, Eagle County, Colorado, yielded K-Ar age of 63.0 +/-1.5 Ma (sericite). Age calculated using decay constants of Steiger and Jager, 1977 (Earth Planet. Sci. Letters, v. 36, p. 359-362). Age probably indicates time of alteration [Paleocene (close to Cretaceous-Tertiary boundary), based on time scale of Berggren, 1972, Lethaia, v. 5, no. 2, p. 195-215]; time of emplacement is somewhat older.

Source: Publication.