Alex L. Sessions

Division of Geologic and Planetary Sciences, MC 100-23 Phone: (626) 395-6445
California Institute of Technology email:
Pasadena, CA 91125 web:

Research Interests

Isotopic biogeochemistry and organic geochemistry, including: biogeochemistry of marine sediments and the deep subsurface; controls on the distribution of hydrogen isotopes in lipids, sedimentary organic matter and petroleum; biomarker and isotopic records of the Neoproterozoic. Also, the development and application of novel isotopic analytical methods for biogeochemistry, such as the analysis of whole cells sorted by flow cytometry.


Ph.D. in Geochemistry, Indiana University, Bloomington, Indiana, July 2001.
M.Sc. in Geochemistry, Dartmouth College, Hanover, New Hampshire, May 1996.
B.A. in Geology, Williams College, Williamstown, Massachusetts, June 1991.

Awards and Honors

  • Outstanding student paper award, American Geophysical Union (2001).
  • Biogeochemistry Fellowship, Indiana University (1996-97).
  • Strohbehn Fellowship, Dartmouth College (1994).
  • Presidential Fellowship, Dartmouth College (1993-94).
  • Graduate Fellowship Honorable Mention, National Science Foundation (1993).
  • Degree with highest honors, magna cum laude, Phi Beta Kappa, Williams College (1991).

Professional Experience

  • California Institute of Technology, Pasadena, California: Assistant Professor of Geobiology. Teaching and research, with an emphasis on isotopic biogeochemistry. Faculty member of geobiology, geochemistry, and environmental science & engineering option programs. August, 2003 – present.
  • Woods Hole Oceanographic Institution, Woods Hole, Massachusetts: Postdoctoral Investigator with Dr. John M. Hayes. Research focus on developing a liquid chromatography/isotope-ratio-monitoring interface for C-isotopic analyses of nonvolatile organic compounds, and application to nucleic acids and microbial ecology. July 2001 – June 2003.
  • Indiana University, Bloomington, Indiana and Woods Hole, Massachusetts: Graduate student with Dr. John M. Hayes. Research focus on microbial fractionation of hydrogen isotopes, and on development of gas chromatography/isotope-ratio-monitoring system for measuring H-isotopic ratios in individual organic compounds. September 1996 – July 2001.
  • Rizzo Associates, Inc., Natick, Massachusetts: Geologist. Responsibilities included design and implementation of hazardous waste site investigations and preliminary Risk Assessments; coordination and quality control review of contract laboratory data; and project management. June 1991 – July 1993 and July 1995 – July 1996.
  • Dartmouth College, Hanover, New Hampshire: Graduate student with Dr. C. Page Chamberlain. Research focus on experimental determination of oxygen isotope fractionation factors for zircon using high-pressure piston-cylinder press and laser-fluorination isotope ratio measurements. September 1993 – June 1995.

Field Experience

  • June, 2004. Ten days in Santa Monica and Santa Barbara basins aboard the R/V New Horizon; CTD casts, in-situ seawater filtering, box-, gravity-, and multi-coring.
  • June, 1994. Three weeks in Connemara, Ireland: Geothermometry studies of early Paleozoic metasediments in western Ireland.
  • August, 1990. Six weeks in western Wyoming and central Montana: Yellowstone-Bighorn Research Association Geology Field Camp.
  • July, 1990. Four weeks in the Blue Ridge of western Virginia: Structural history of the Rockfish Valley Deformation Zone.


A complete list of publications, and a partial list of presentations, are available.


Born in 1969, I grew up in the Shenandoah Valley, nestled between the Blue Ridge and Alleghany Mountains of western Virginia. Chris Reddy thinks this may explain my penchant for bluegrass and flannel. After spending most of the past 16 years in New England, I now reside in Pasadena, CA with my wife Karen our children Stuart and Amy. My hobbies include mountain biking, hiking and camping, photography, woodworking, and the occasional fishing trip.