Pg. 306. Mentioned the pre-Cambrian Coal Creek quartzite and Ralston formation, both of sedimentary origin, of Boulder region, central northern Colorado, but did not define them, and stated they were taken from unpublished thesis of J. Adler, Univ. Chicago, 1930. Both are intruded by Boulder Creek granite gneiss.

Source: US geologic names lexicon (USGS Bull. 896, p. 472).

Coal Creek quartzite. Fine-grained quartz-muscovite-biotite schist interbedded with the quartzite contains a few garnet crystals and, locally, abundant cordierite. Believed to be younger than Idaho Springs formation and older than some of the granite in the area. Outcrop area described. Age is Precambrian.
Crops out in triangular area 7 mi long and up to 3 mi wide near mouth of Coal Creek Canyon, Jefferson and Boulder Cos., central northern CO.

Source: US geologic names lexicon (USGS Bull. 1200, p. 854).

Pg. D4 (table 1). Coal Creek Quartzite of Boos and Boos (1934). Invalid; incidental mention without definition; rocks generally mapped as a lithic unit or as quartzite of Coal Creek. Rocks included in pre-1,700 Ma complex (Precambrian X), east-central Front Range, Colorado.
(See also J.D. Wells, 1967, Geol. Eldorado Springs quadrangle, Boulder and Jefferson Cos., CO, USGS Bull. 1221-D; Wells and others, 1964, USGS Prof. Paper 454-O, 25 p.)

Source: Publication.