Geologist Peter Wessel Birkeland died of natural causes in Boulder, Colorado, on January 25, 2022.

Birkeland was born in Seattle, Washington, on September 19, 1934, to Norwegian immigrant Ivar Wessel Birkeland and Marguerite Ellen O’Conner Birkeland of Rochester, Minnesota, and grew up in the Seattle area. He served in the U.S. Army from 1953 to 1955, ending his service as a ski trooper in the Mountain and Cold Weather Training Command at Camp Hale in Colorado. In 1958, he graduated from the University of Washington in Geology, and in 1961 he completed a Ph.D. in Geology from Stanford University, studying under Art Howard and J. Hoover Mackin.

Birkeland’s professional career began in 1962 as an instructor and assistant professor at the University of California, Berkeley. In 1967, he took a position in the Department of Geological Sciences at the University of Colorado–Boulder, where he taught and conducted research in soils and Quaternary geology until his retirement in 1997.

Birkeland was a prolific researcher for more than four decades. His work was geographically broad and generated a steady stream of publications, commonly with his students. His main area of research was soil geomorphology — the application of pedology to address landform and landscape evolution. This work had tremendous importance to Quaternary stratigraphic, neotectonic, and paleoclimatic problems.

Birkeland’s remarkable accomplishments in research resulted in Distinguished Career Awards from both the Quaternary Geology and Geomorphology Division of the Geological Society of America (2000) and the American Quaternary Association (2009), but his proudest professional accomplishment was his mentoring and training of many successful students in this field, all of whom became his colleagues and cherished friends.

— Portions of text courtesy of the Geological Society of America and the Daily Camera (Boulder)