1906 – Born on May 24th in New York City. Harry was the sixth Blair Professor of Geology.
1932 – Took his Ph.D. degree at Princeton University.
1930 – Hess participated in submarine gravity studies of the West Indies island arc, and, in order to facilitate operations on Navy submarines, he acquired a commission as lieutenant, junior grade, thus initiating a long association with the United States Naval Reserve, where he ultimately rose to the rank of rear admiral.
1934 – Hess spent a year as an instructor at Rutgers and another as a research associate in the Geophysical Laboratory of the Carnegie Institution of Washington before joining the Princeton faculty as instructor.
1941 – Called to active duty, he discharged important wartime duties and, at the same time, kept alive his scientific curiosity.
1950 – He followed his principal teacher and close friend, Arthur Buddington, as chairman of the department.
1952 – Following his election to the National Academy of Sciences, Hess was called on frequently to head national scientific committees, serving as chairman of the Academy’s Committee for Disposal of Radioactive Wastes, the National Research Council’s Earth Sciences Division, and the Academy’s Space Science Board, which was established to advise the National Aeronautics and Space Administration on scientific aspects of the development of the national space program.
1960 – Hess made his single most important contribution, which is regarded as "part of the major advance in geologic science of this century". In a widely circulated report to the Office of Naval Research, he advanced the theory, now generally accepted, that the earth’s crust moved laterally from long, volcanically active oceanic ridges. "Sea-floor spreading", as the process was later named, helped establish the concept of continental drift as scientifically respectable and triggered a "revolution in the earth sciences".
1962 – This report was formally published in his History of Ocean Basins, which for a time was the single most referenced work in solid-earth geophysics.
1966 – He also served as president of the Mineralogical Society of America, as well as of the Geological Society of America, which gave him its highest award, the Penrose Medal.
1969 – His death, of a heart attack, occurred on August 25th, in Woods Hole, Massachusetts, while he was presiding at a Space Science Board conference he had organized to reformulate the scientific objectives of lunar exploration.