Pg. C13-C15. Badger Creek Tuff. A compound-cooling unit consisting of at least six ash flows. Previously called tuff of Badger Creek. Is light-gray to reddish-brown tuff; weathers yellowish-gray to buff. Has a salt-and-pepper appearance due to abundance of black biotite and hornblende crystals mixed with light-pink and white pumice lapilli. Thickness 313 feet at type locality; locally as much as 800 feet. Is nearly equivalent to Antero Formation. Rests on Precambrian crystalline rocks, Wall Mountain Tuff, or Tallahassee Creek Conglomerate. Is overlain by a local latite flow. Has reverse remanent magnetic polarity. Age is Oligocene.
Type locality: in valley of East Badger Creek, in NE/4 sec. 12, T. 50 N., R. 10 E., 17.7 km northeast of Salida, Cameron Mountain quadrangle, Fremont Co., central CO.

Source: US geologic names lexicon (USGS Bull. 1200, p. 15); GNU records (USGS DDS-6; Denver GNULEX).

Intertongues with Antero Formation (as revised in this report is equivalent to only the middle part of Johnson's (1937) Antero). In the South Park basin. Assigned an Oligocene age.

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

Pg. 16, geologic time scale (inside front cover). Badger Creek Tuff. An andesitic ash-flow tuff, underlies Buffalo Peaks Andesite and overlies Wall Mountain Tuff. Sample from Lat. 38 deg. 49 min. 20 sec. N., Long. 105 deg. 56 min. W., in NE/4 NE/4 sec. 22, T. 14 S., R. 77 W., Antero Reservoir 15-min quadrangle, Chaffee County, Colorado. [K-Ar] age on hornblende 37.4 +/-0.7 Ma; on biotite 36.3 +/-0.9 Ma. Decay constants of Steiger and Jager, 1977 (Earth Planet. Sci. Letters, v. 36, p. 359-362) are used. [Age is close to Eocene-Oligocene boundary, 36.6 (38 to 34) Ma (from Geologic Names Committee, USGS, 1983 ed. geol. time scale, with additions from N.J. Snelling, 1985, The Geol. Soc. Mem., no. 10).]

Source: Publication.