I joined the Geosciences Department at UMass in January, 2001 after 11 years at the University of Bern in Switzerland. I was an undergrad at Rice University, and went on to do an M.S. at the University of North Carolina studying carbonate sedimentology and a Ph.D. at Duke University on dolomite geochemistry.
My research interests are broad, but mostly fall into two areas: paleoclimatology and sediment diagenesis. In both of these I use stable isotopes as a research tool. Over the past several years, my research has focused on developing records of climate change on the continents. While the broad outline of climate variation over the past several million years is fairly well known, the causes of climate change on various time scales are not. Also, climate on the continents is much more spatially variable than in the oceans. Thus, my research is aimed at producing quantitative estimates of climate change from continental areas at high enough resolution to be able to determine the driving forces behind climate change at various time scales.
One of the main archives of climate information that I am interested in is speleothems, the family name for cave deposits such as stalagmites and stalactites. Speleothems faithfully record changes in the climate signal contained in O and H isotope ratios of rainfall. I like to think of them as underground ice cores. IThe great majority of my speleothem-based research has been in the tropics. In previous projects in Oman and Yemen we have produced records of changes in precipitation that extend back over several hundred thousand years. For the most recent climate period, the Holocene, these records are up to annual in resolution. Similar work in Brazil and the Peruvian Andes demonstrates strong asymmetry between the Northern and Southern hemisphere tropical rainfall on timescale ranging from orbital to millennial.
I have two current research projects that use speleothems to investigate climate variability. First, in the Yucatan region of Mexico, Martin Medina (Amherst Collge) and I are speleothems to study the patterns and causes of claimte variability at the edge of the NH tropics. One focus of this work is the relationship between climate and Mayan cultural evolution. Second, Laurie Godfrey (Dept. of Anthropology, UMAss) and I are studying the climate and environmental history of Madagascar and the relationship between climate and the disappearance of Madagascar's megafauna.