ARTHUR L. DAY MEDAL LECTURE: BACKGROUND OF A GEOCHRONOLOGIST

My career path as a geologist began as a Junior at the University of Arizona, when I enrolled in an introductory geology course just for fun. My life changed during the first class field trip, when I realized that one could actually make a living by hiking around in the mountains – what could be better than that? Our inspirational teacher, Doug Shakel, brought geology to life, and I’ve been hooked ever since. While working through undergraduate geology courses I was fortunate to be able to interact with Bob Butler, George Davis, and Peter Coney, and I also worked in Paul Damon’s K-Ar lab. With these professors as my mentors and heroes, I became intrigued about the connections between tectonics and geochronology, and decided to pursue graduate studies in these fields. This led me to work with Greg Davis at the University of Southern California, where I learned how to use a geologic map as a problem-solving tool, and was exposed to the exciting new concepts of accreted terranes and metamorphic core complexes. I then started PhD research at Caltech, working with Jason Saleeby and Henry Berg (USGS) on the geology of southeast Alaska. It was a privilege to work with such dynamic and creative geologists, to take advantage of the world-class geochronologic facilities and experise at Caltech, and to spend several months each year mapping in the Alexander terrane. I was then very fortunate to join the faculty at the University of Arizona in 1985 and begin a career in geochronology and tectonics. Sharing lab facilities with Jonathan Patchett and Joaquin Ruiz has been a fabulous arrangement, and I have developed close collaborations with colleagues Bob Butler, Bill Dickinson, Pete DeCelles, and Paul Kapp. Perhaps the most rewarding aspects of my faculty career have been to teach geology and oceanography to large numbers of non-majors, to help undergraduate and graduate students in Geosciences become involved in research, and, with support from the University of Arizona and the National Science Foundation, provide opportunities for investigators from other institutions to use U-Pb geochronology to address questions in tectonics and many other fields ranging from planetary evolution to the chronology of early hominids.