August 2010 - present - Professor of Geology, San Diego State University

August 2003 – August 2010- Chair, Department of Geological Sciences, San Diego State University

September 2001 –August 2003 - Professor of Geology, San Diego State University

August 1998-August 2001 - Chair, Department of Geological Sciences, San Diego State University

August 1990–present – Professor of Geology, San Diego State University

August 1984-August 1990-Associate Professor of Geology, San Diego State University

July 1982–August 1984 – Assistant Professor of Geology, University of Kansas

July 1980–July 1982 – Texas Miocene Group Geologist, Shell Oil Company, Western District Cenozoic, P.O. Box 60124, New Orleans, LA 70160

Spring 1980 – Mineralogy Lecturer, Queens College, New York, New York

Fall 1977–July 1980 – Graduate Research Associate, Columbia University, New York, New York

September 1976 – June 1977 – Marine Science Technician, Glomar Challenger, Scripps Institute of Oceanography, University of California, San Diego, California

1967–1970 – United States Armed Forces, Fairbanks, Alaska, Honorable Discharge