Major ignimbrites and volcanic centers of the Copper Canyon area: A view into the core of Mexico's Sierra Madre Occidental Swanson, Eric R. ; Kempter, Kirt A. ; McDowell, Fred W. ; McIntosh, William C. Abstract Publication: Geosphere Pub Date: 2006 DOI: 10.1130/GES00042.1 Bibcode: 2006Geosp...2..125S