Harry Hammond Hess

1906-1969

American Geologist

Born in New York in 1906, Harry Hammond Hess was considered a "very promising student" even in his high school years. He had no difficulty gaining acceptance into the electrical engineering major group at Yale University in New Haven, Connecticut. However, after two years, he elected to change his major to geology and received his B.S. in that field in 1927.

Prior to his graduate studies at Princeton University, Hess spent two years in south central Africa (formerly Rhodesia) working as an exploration geologist. He returned to America and earned his doctorate at Princeton. This led to a year of teaching at Rutgers University and another year as a research associate at the Geophysical Laboratory in Washington, D.C. He then rejoined the faculty at Princeton, where he remained for the balance of his career.

His academic career was interrupted by World War II, during which he enlisted in the U.S. Navy and attained the rank of captain. Even while he was engaged in the conflict in the Marianas, Leyte, Linguayan, and Iwo Jima, Captain Hess (with the cooperation of several crew members aboard the U.S.S. Cape Johnson) conducted echo-sounding surveys while en route to various battles. These soundings gave Hess the data he needed to form ocean floor profiles across the North Pacific Ocean, resulting in his finding a series of flat-topped volcanoes beneath the surface. His loyalty to Princeton influenced his calling the volcanoes "guyots" after the university Geology Building.

Later, in 1957, Hess supported the Mohole Project (initiated by Walter Munk), to drill through the oceanic crust, deep into the earth's mantle. The pair arranged support and settled on the initial venture off Guadalupe Island, Mexico. By the time the second phase of the project was cancelled by Congress in 1966, many of the problems of ocean drilling had been solved, making the task much easier for subsequent scientific ocean drilling teams.

In 1959 Hess published an informal manuscript that was widely circulated and introduced a groundbreaking process that would later be known as seafloor spreading. By 1962 these ideas were formalized in a paper that became one of the most important documents in the science of plate tectonics—History of Ocean Basins.

Its importance was based on the question geologists had pondered for many years: If the oceans were at least 4 billion years old, why was there so little sediment found on the floors? Hess hypothesized that the sediment had been accumulating for about 300 million years. He reasoned that this would be the approximate time needed for the floor of the ocean to move from the ridge crest to the trenches.

Hess's ideas were particularly interesting to followers of an earlier geologist, Alfred Lothar Wegener (1880-1930), who proposed that pieces of the original continents may have broken up and drifted apart to form the areas we know today as continental formations. Several new theories were developed but, finally, improved seismic data confirmed that portions of the ocean's crust were sinking into trenches, lending credence to prove Hess's hypothesis, which originally was based on intuitive geologic reasoning.

Hess continued to head the Geology Department at Princeton until his death in 1969. Unlike his predecessor, Wegener, he lived to see his work accepted, confirmed, and expanded. In recognition of his contributions to global knowledge and better understanding of our planet, in 1962 President John F. Kennedy appointed Hess to serve as Chairman of the Space Science Board of the National Academy of Sciences. From this position he played a significant part in the design and development of the United States space program.

BROOK ELLEN HALL