My interests lie at the interface of geological, ecological, and atmospheric sciences and focus specifically on the interaction of lakes with the atmosphere and the land surface, both in contemporary times and during the Quaternary. I specialize in the application of diatom analysis to questions of environmental change, although my current projects complement diatom-based reconstructions with geochemical and geomorphic approaches. My research also combines studies of lacustrine stratigraphic records with descriptive and experimental studies of modern lakes as models for interpretation of fossil sequences. My current research projects focus on long-term hydrologic variability in tropical South America and in the Great Plains and Rocky Mountain regions of North America.