William Bullock Clark was born in Brattleboro, Vermont on December 15, 1860. He received his A.B. from Amherst in 1884 and his Ph.D. from the University of Munich in 1887. While pursuing his doctorate, Clark also studied in London and Berlin, and was a field surveyor with the geological surveys of Great Britain and Prussia.
Clark came to the Hopkins Department of Geology (the present Earth and Planetary Sciences Department) in 1889, became the department chairman in 1892, and was promoted to full professor in 1894. In addition to his responsibilities at Hopkins, he served as a geologist in the United States Geological Survey, organized the Maryland State Weather Service, and established the Maryland State Geological Survey.
On October 12, 1892, Clark married Ellen C. Strong of Boston. They had four children, Helen, Marion, Edward S. and Atherton. Clark died on July 27, 1917 of a stroke, and was survived by his wife and children.