AGU member since 1985. Professor of Geochemistry, Department of Earth Sciences, University of Oxford, since 2004. Research has focused on using isotope geochemistry to study silicic magmatism, crustal fluid flow, lower crustal processes, and mantle geochemistry. More recently, interests have broadened to the origin and early differentiation of the terrestrial planets and large-scale surface processes such as ocean circulation. An underlying research theme has been the development and use of new isotopic methods. Since 1992, this has focused on MC-ICPMS. B.S., Geology, 1973, Ph.D., Physics, 1977, University of Newcastle-upon-Tyne. Lecturer, Scottish Universities Research and Reactor Centre, 1981–1986; professor, University of Michigan, 1986–1998; professor, ETH Zurich, 1998–2004, department head, 2002-2004. President, Geochemical Society (GS), 1995-1997; Patterson Medal Committee, GS, chair, 1997-1998; Fellows Committee, European Union of Geosciences, 1999–2003; Clark Medal Committee, GS, 2000–2003; Urey Medal Committee, European Association of Geochemistry (EAG), 1996–1997, 1999–2000, 2004 to present, chair; vice-president, EAG, 2004–present. Convenor, Origin of the Earth and Moon Meeting, Monterey, 1998. Convenor, Goldschmidt Conference, Davos, 2002. Associate Editor, Geochimica et Cosmochimica Acta, 1990-1995; Editor, Earth and Planetary Science Letters, 1999 to present; Board of Reviewing Editors, Science, 2001–2003. IPG, Paris, Conseil Scientifique, 2001–2003; MPI, Mainz, Advisory Board, 2001 to present; NERC, Council, 2004 to present. About 250 refereed papers. VGP Bowen Award, 1998; AGU Fellow, 2000; Fellow of the Royal Society, 2000; GS-EAG Geochemistry Fellow, 2001; Geological Society, Murchison Medal, 2003; Mineralogical Society, Hallimond Lecturer, 2004; Royal Society-Wolfson Research Merit Award, 2004. AGU, Publications Committee, 1994–1996; VGP Macelwane Committee, chair, 2000–2002; VGP Fellows Committee, chair, 2004 to present.