Chris Hawkesworth has made fundamental contributions to our understanding of a broad range of geochemical problems, including the geochemistry of continental flood basalts, the petrology and geochemistry of granites, the geochemistry of Andesitic volcanoes, the origin of postcollisional shoshonites, the relative importance of slab and mantle wedge contributions to arc magmas, Holocene climate change, dating major archeological episodes, tracing brain disease with zinc isotopes, monitoring the consequences of a snowball Earth with calcium isotopes, and uranium series dating, to name a few. In collaboration with Simon Turner, he used uranium series disequilibria to show that timescales for the mantle processes that give rise to basaltic arc magmas are a few thousand years or less, whereas the crustal residence times for silicic magmas are tens to hundreds of thousands of years. He also pioneered the use of hafnium and oxygen isotopes in zircon, in conjunction with Tony Kemp, to distinguish between recycled crust and new additions to the continental crust.

Chris is inherently inquisitive and has the ability to link disparate data sets to understand processes of global significance. His work sets, rather than follows, the research agenda. It is insightful and innovative and addresses fundamental problems at the forefront of the Earth sciences. Earth is a dynamic and complex physiochemical system that operates across a range of spatial and temporal scales, and Chris is able to integrate information from across this system.

Leadership and service contributions by Chris are equally impressive as those related to his scientific research. He has established new and cutting-edge infrastructure facilities for Earth sciences research at the various institutions where he has worked, he has chaired review panels of Earth science departments in various countries to guide their future development, and he was part of the review panel for the key international program in the Earth sciences, the International Ocean Drilling Program. Chris served as president of the European Association of Geochemistry, as a director of the Geochemical Society and as a member of the European Geosciences Union Council. As deputy principal and vice-principal for research at the University of St Andrews, he significantly raised the research profile of the university. He has also been an editor of Earth and Planetary Science Letters (1985-1993) and Science (2004-2011). The geochemical community is fortunate to have had a member who has made numerous selfless contributions to the community and nurtured the many talented young scientists who have passed through his laboratory.

— Ian Campbell
The Australian National University
Canberra, ACT, Australia

Thank you for your very generous words; I am deeply honored to have been awarded the Walter H. Bucher Medal by AGU. Walter Bucher was grappling with deformation of Earth’s crust, commenting that there were a multitude of conflicting views concerning the forces that deform Earth’s crust. That sounds very familiar to many present discussions of the early lithosphere, but it has been a rich and enjoyable journey which I feel very lucky to be part of.I would not be here if Ron Oxburgh had not taken on this barely underqualified graduate to do a Ph.D. in the Eastern Alps with a great group of students that included Mike Bickle, Philip England and Dave Waters, who together laid the foundation for much of the geology that I have picked up. A big thank-you to Ron and to Keith O’Nions and Claude Allegre for their help and support and to all three for their efforts in bringing the European Earth sciences together as the community it is today. Working in the Alps highlighted the importance of teams with people with different skills and interests working together on a shared topic, if possible with a field geology focus, that has stayed with me thereafter. Much of my research has involved teams and research groups, and any success is very much down to all of them.Ian Gass went against much of the conventional wisdom of the time to set up a new isotope research group at the Open University. That was an unexpected opportunity for a group of young scientists to branch out and to help in the early efforts to encourage research at this distance learning university. Ideas were shaped in discussions with Geoff Brown, Nigel Harris, Julian Pearce, Peter Francis and Simon Turner in this exciting new Earth Sciences Department. Bristol opened new doors and opportunities, relishing in the setting up of a new isotope group by Tim Elliott, Geoff Nowell and Chris Coath and enjoying the interactions with Jon Blundy, George Helffrich, Mike Kendall, Steve Sparks and Bernie Wood. There have been richly rewarding collaborations with Bruno Dhuime, Peter Cawood and Tony Kemp which have tried to shape some of the discussion of Archaean tectonics. I am very much in their debt, as I am to my wife, Celia, as we have shared a wonderful journey together in our different academic worlds.— Chris Hawkesworth, University of Bristol, Bristol, United Kingdom