John Spencer from the Arizona Geological Survey will be the featured speaker at an upcoming Department of Geoscience seminar. His talk is titled, "Critical-taper theory in extensional tectonics as revealed by the Buckskin-Rawhide Mountains area, western Arizona."

Spencer has made significant contributions toward understanding the Mesozoic and Cenozoic tectonics of the southwestern U.S. and in extensional systems on continents, ocean basins, and other planets.