Me & Stu


Division of Geological and Planetary Sciences, MC100-23
California Institute of Technology
Pasadena, CA 91125

Office phone: 626-395-6445
Lab phone: 626-395-6643
Fax: 626-683-0621

email: ALS (at)

Research Interests

Stable isotope biogeochemistry and organic geochemistry, including: biogeochemistry of marine sediments and the deep subsurface; controls on the distribution of hydrogen and sulfur isotopes in lipids, sedimentary organic matter and petroleum; biomarker and isotopic records of the Precambrian. Also, the development and application of novel isotopic analytical methods for biogeochemistry, such as compound-specific analysis of 34S in volatile organics, and isotopic clumping and ordering in organic molecules.


Ph.D. in geochemistry, Indiana University, Bloomington IN, July 2001
M.Sc. in geochemistry, Dartmouth College, Hanover NH, May 1996
B.A. in geology, Williams College, Williamstown MA, June 1991

Professional Experience

• Co-Director, International Geobiology Course, Pasadena CA. 5-week graduate training course. June 2017 – present.
Professor, California Institute of Technology, Pasadena CA. Still more research and teaching. September 2010 – present.
• Associate Professor, California Institute of Technology, Pasadena CA. More research and teaching. June 2010 - September 2010.
• Assistant Professor, California Institute of Technology, Pasadena CA. Research and teaching. August 2003 – June 2010.
• Postdoctoral Investigator, Woods Hole Oceanographic Institution, Woods Hole MA. research with Dr. John Hayes. July 2001 - June 2003.
• Research Assistant, Indiana University, Bloomington IN. research with Dr. John Hayes. September 1996 - July 2001.
• Geologist, Rizzo Associates Inc., Natick MA. Evaluation and remediation of hazardous waste sites. June 1991 - July 1993 and July 1995 - July 1996. 

Selected Field Experience

June 2017, 2018, 2019. Ten days per year in Owens Valley & Mono Lake as director of the International Geobiology Course.
October 2013. Fourteen days on R/V Atlantis exploring and sampling in Santa Barbara and Santa Monica Basins via ABE and JASON.
June, 2008, 2010, 2011, 2012, 2013. 6-10 days per year in Yellowstone NP, Great Salt Lake, and southwestern WY as an instructor in the Agouron International Geobiology Course.
July, 2007. Seven days on the R/V Robert Gordon Sproul in the northeastern Pacific filtering POM.
March, 2007. Ten days in South China sampling Neoproterozoic sediments of the Nanhua Basin.
June, 2004. Ten days on the R/V New Horizon in the California Borderland Basins filtering POM and coring shallow sediments.
June, 1994. Three weeks in Connemara, Ireland studying early Paleozoic metasediments.
August, 1990. Six weeks in western Wyoming and central Montana, geology field camp.
July, 1990. Four weeks in western Virginia studying structural history of the Blue Ridge Mountains. 

Professional Organizations

Geochemical Society, Organic Geochemistry Division
European Association of Organic Geochemists
American Geophysical Union
Geological Society of America


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


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 16 or so (who's counting?) years of school in New England, I now reside in Pasadena, CA with my wife Karen and our children Stuart and Amy. My hobbies include mountain biking, hiking and camping, woodworking, and the occasional fishing trip.

Alex ski

Copyright 2015 by Alex Sessions. All rights reserved.