Robert J. Poreda PhD. in Earth Sciences, University of California, San Diego 1983 Professor of Earth and Environmental Sciences Email: poreda@earth.rochester.edu

                  Dr. Poreda has applied the isotopic composition of the rare gases (He, Ne, Ar, Kr, and Xe) and light elements (H, C, O, N) to problems of crust-mantle evolution, origin of the atmosphere, hydro-thermal circulation, origin of natural gases, ground-water flow, and erosion rates of crustal rocks. He has established a state-of-the art rare gas facility capable of extracting and analyzing the isotopic compositions of gases at extremely low levels (to 1000 atoms). Rather than focusing on a single niche of isotope geology, Dr. Poreda has found an extremely wide range of applications for his isotope trace techniques. He has collaborated and written papers with igneous petrologists, petroleum geologists, volcanologists, hydrologists, and sedimentologists. Using the isotopic composition of the rare gases from South Pacific oceanic island basalts, he is attempting to unravel the complexities of mantle evolution. Using cosmic-ray produced 3He and 21Ne, he has been able to date the age of surfaces which are not able to measured by conventional means (14C) and determine the rates of sedimentary processes such as rates of erosion and the timing of glacial retreat. In hydrology, he has shown the applicability of the decay of tritium to 3He in problems of groundwater flow. Consistent age and hydraulic conductivity information can be obtained using this technique which has many advantages over tritium alone. He is an active, sea-going oceanographer who has participated in a number of expeditions over the years, recently completing a mapping and dredging cruise in the Southeast Pacific.