Professor, Geological Sciences
My main research projects include 1) paleogeographic and geotectonic history of the Argentine Precordillera based on U-Pb geochronology of detrital zircons from Cambrian to Carboniferous sandstones; 2) the Late Ordovician mass extinction; 3) the stratigraphy and structure of the Roberts Mountains allochthon of north-central Nevada; 4) paleobiology and biostratigraphy of graptolites; and 5) Chronostratigraphy.
I have a well equipped macrophotography lab for the study and illustration of graptolites. I am regularly in the field in Nevada and Argentina. U-Pb geochronology of zircons is carried out with colleagues and instrumentation at the University of Arizona and UCLA.
I currently serve as Vice-chair of the International Commission on Stratigraphy (2000-2008) and previously served as Chair of the ICS Subcommission on Ordovician Stratigraphy (1996-2004). I also serve as co-Director of the Environmental Science & Policy degree programs.
I teach Paleontology & Biostratigraphy (GEOL 341), Summer Field Geology (GEOL 450), and California Environmental Issues (ES&P 400).