A member of the Hamilton College faculty since 1978, Tewksbury earned a Ph.D. in geology from University of Colorado and has held three different endowed chairs at Hamilton. She is a structural geologist and is currently engaged in research projects in Iceland and in Egypt. Tewksbury has also played a leadership role in the national geoscience education community for over 15 years and has given dozens of workshops to faculty in departments across the country and abroad. She has been awarded nine different NSF grants to fund both her research and her work in geoscience education. Tewksbury is a past president of the American Geological Institute and the National Association of Geoscience Teachers. She was named New York State Professor of the Year in 1997 by the Carnegie Foundation for the Advancement of Teaching and was the 2004 recipient of NAGT's Neil Miner Award for exceptional contributions to the stimulation of interest in the Earth Sciences. In 2006, she received an honorary degree from St. Lawrence University for her work in geoscience education.