• Francis Brown Presidential Chair, Geology & Geophysics
  • Chair Department of Geology and Geophysics
  • Distinguished Professor, Biology
  • Distinguished Professor, Geology & Geophysics

Research Summary

I do research using isotopes to study natural processes in geology and biology. Projects include landform evolution using cosmogenic isotopes, geochronology using radioisotopes, ecology and paleoecology using stable isotopes, forensics using both radiogenic and stable isotopes. I do field work on wildlife ecology, surface processes and geology.


  • BSc, Geology, Chemistry, Iowa State University
  • MSc, Geology, Iowa State University. Project: Correlation of tuffs in the Lake Rudolf region of Kenya
  • PhD, Geology, University of California Berkeley. Project: Paleochemistry of Lake Turkana


I use stable isotopes to understand ecological questions such as soil formation, animal physiology, wildlife ecology, and climate change. I work on time scales that include current (and future) events, but also work on fossil systems up to millions of years old.