Pg. 9. Square Peak Volcanics. Rhyolite and quartz trachyte samples from Lasca and Silver King Canyon quadrangles, Culberson County, southwestern Texas, yielded K-Ar ages of 34.1 +/-1.3 Ma and 32.9 +/-1.0 Ma (whole-rock), respectively. Ages are suspect. Data from Jeremy Setter and J.A.S. Adams, 1986 (Univ. Texas-Austin Bur. Econ. Geol. Gdbk. 23), W. Shannon and P.C. Goodell, 1986 (Univ. Texas-Austin Bur. Econ. Geol. Gdbk. 23), and C.C. Albritton and J.F. Smith, 1965 (USGS Prof. Paper 479, 131 p.); ages recalculated using decay constants of Steiger and Jager, 1977 (Earth Planet. Sci. Letters, v. 36, p. 359-362).
[Age possibly Oligocene; Eocene-Oligocene boundary 36.6 (38-34) 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.
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).