Paul F. Hoffman leads a research group studying the Proterozoic-Cambrian transition, with particular focus on the so-called "snowball earth" episodes as manifestations of the most extreme climate states (hot and cold) the terrestrial biosphere ever encountered. The group works mainly on seawater proxy records in marine carbonate sections on ancient continental margins. This involves extended field work in remote areas of the Arctic and subtropical Africa. Stable isotopes are a mainstay of the group's work, with carbon and oxygen isotopes being studied in close collaboration with Harvard astrobiology team member Dan Schrag, and sulfur isotopes with Penn State astrobiology team member Matt Hurtgen. Hurtgen participated in our recent field expeditions in Namibia and Svalbard. The group also does paleomagnetic and geochronological work, the former with Joe Kirschvink and the latter with Sam Bowring of the Caltech and MIT astrobiology teams, respectively. In fact, the groups' collaborations are now almost exclusively with NAI members. NAI supports two doctoral candidates, Galen P. Halverson, who will complete his thesis on the Neoproterozoic of Svalbard in early 2003, and Adam C. Maloof, who will complete his thesis on the Cambrian-Neoproterozoic transition in Morocco in 2004.

Courses Related to Astrobiology:
Hoffman and Schrag co-teach a course on the History of the Earth, which is one of three introductory courses required of all concentrators in the Department of Earth and Planetary Sciences. The course takes a planetary perspective on the subject. Hoffman will offer a freshman seminar in alternate years beginning 2003 on Why Did Intelligence Evolve on Earth?