I am a carbonate sedimentologist-stratigrapher and focus research on paleoclimatologic and paleoceanographic change in deep time (pre-Cenozoic). Within a detailed cyclostratigraphic and sequence stratigraphic framework, my students and I utilize a range of stratigraphic, geochemical, and paleontological tools to evaluate paleoenvironmental change occurring on time scales ranging from millennia, orbital (10⁴-10⁵ yrs), My-scale, to many tens of millions of years. This research includes field-oriented cyclo- and sequence stratigraphic studies across large Precambrian, Paleozoic, and Mesozoic carbonate platforms to understand the evolution of carbonate depositional systems and the patterns of high-frequency cycle development during greenhouse (warm), icehouse (cool) and transitional climates.

More recently, our research group has focused on utilizing geochemical techniques (O-C stable isotopes from marine apatite and calcite, Nd and Sr radiogenic isotopes, trace elements, organic carbon) to evaluate and quantify the range of paleoclimate change observed in Proterozoic through Tertiary marine successions. Our results are suggesting that the Earth’s climate does not swing from uniformly warm (greenhouse) to uniformly cool (icehouse) climates; rather greenhouse climates are characterized by cyclic pulses of cooler times; cool enough for polar regions to accumulate significant quantities of glacial ice and drive global climates and sea level changes.

Field areas include many parts of the western U.S. (Nevada, Utah, Wyoming, Montana, Idaho, New Mexico, Arizona), western Canada, northern and central Mexico, and Europe (Czech Republic, southern France, northern Spain).