Hess, H. H.

Hess, H. H. (Harry Hammond) (1906–69) geophysicist; born in New York City. While serving with the U.S. Navy in the Pacific during World War II, Hess not only located submarines with sounding gear, but was the first to report the existence of the truncated seamounts known as guyots. He led Project Mohole, the first expedition to drill through the earth's oceanic crust to the mantle beneath (1961–66). His long-term interest in the igneous rock peridotite led to his proposal that this high-temperature substance was basic to investigations of island arc formation, gravity anomalies, mountain building, and the earth's deeper crustal structure. While Chairman of Princeton's geology department (1950–66), he accurately theorized that spreading of mid-ocean ridges was the source of new mantle-derived continental material. As an adviser to the National Aeronautics and Space Administration (NASA), Hess was one of the first scientists to examine lunar rocks.