Name given to sequence of rocks previously assigned to the upper part of the Sawatch Quartzite in the Taylor Park area, western Gunnison Co, CO in the Piceance basin, for Deadmans Gulch. Type section measured on south slope of gulch in sec 14, T14S, R84W, where formation overlies Glenwood Canyon Member of Peerless Formation and conformably underlies Manitou Formation. Is 86.5 ft thick at type and consists of 1) a lower member of gray-orange, calcareous, fine to medium crystalline dolomite and light red, dolomitic, fine-grained, medium-bedded quartz arenite; 2) a middle member of light gray, slightly dolomitic, fine-grained, massive quartz arenite; and 3) an upper member of white, fine-grained, massive quartz arenite with 2 ft thick layers of brown calcareous arenite. Detailed lithologic description. Isopach map. Recognized also in western Park Co, South Park basin, and in eastern Eagle Co, eastern Pitkin Co, southern Summit Co, Lake Co, and northern Chaffee Co in the Eagle basin, CO. Is more than 100 ft thick. Thins to east and to northwest. Is missing elsewhere in central CO. Cross sections. Late Cambrian age. Was deposited in a gradually subsiding tectonically active, northwest-southeast elongate basin. Peerless was concurrently deposited on the more stable supratidal-intertidal environment to north.

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