40Ar/39Ar and K-Ar geochronology and tectonic significance of the Upper Cretaceous Adel Mountain volcanics and spatially associated Tertiary igneous rocks, northwestern Montana / 
By Stephen S. Harlan ... [et al.]. 
 - Reston, Va. ;  Denver, CO :  U.S. Geological Survey :  U.S. Geological Survey, Information Services [distributor],  2005. 
 - iv, 29 p. :  col. ill., maps (some col.) ;  28 cm. 
 - Professional paper ;  1696 .
 - U.S. Geological Survey professional paper ;  1696. .
<br/><br/>Includes bibliogr.l references (p. 18-19). 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geochronometry--Montana--Craig Region.<br/>Rocks, Igneous--Montana--Craig Region.<br/>Geology, Stratigraphic--Cretaceous.<br/>Geology, Stratigraphic--Tertiary.<br/>Radioactive dating--Montana--Craig Region.