40Ar/39Ar ages of some Challis Volcanic Group rocks and the initiation of Tertiary sedimentary basins in southwestern Montana /
M'Gonigle, John W.
Dalrymple, G. Brent.
Washington : U.S. G.P.O. ; Denver, CO : For sale by the U.S. Geological Survey, Information Services,
1996.
"A summary of ♯⁰Ar/©⁹Ar age analyses of eighteen samples of volcanic rocks from the Challis Volcanic Group and a summary of basin stratigraphy in southwestern Montana."
One folded leaf of plates in pocket.
Includes bibliographical references (p. 6-7).
Rocks, Igneous
Argon-argon dating
Geology, Stratigraphic