Alfred H. Pekarek, Richard F. Marvin, Harald H. Mehnert; K-Ar Ages of the Volcanics in the Rattlesnake Hills, Central Wyoming. Geology ; 2 (6): 283–285. doi: https://doi.org/10.1130/0091-7613(1974)2<283:KAOTVI>2.0.CO;2
Download citation file:
The Rattlesnake Hills of central Wyoming contain approximately 40 volcanic vents and intrusive bodies of alkalic and calc-alkalic composition in a 125-sq-mi area. Two samples, a phonolite and a rhyodacite (quartz latite), dated by the K-Ar method, yielded dates of 43.6 ± 1.0 and 44.0 ± 2.6 m.y., respectively. These dates, combined with stratigraphic evidence of Van Houten (1955) and Carey (1959), indicate a minimum time span of 5 m.y. for the Rattlesnake Hills volcanism.