Learning From Hess *32

Professor Harry H. Hess *32 (Princeton Portrait, January issue) was an amazing fellow, full of stories, and patiently helped me on my senior thesis. He was one of the all-star faculty team-teaching a senior course on big topics. Hess’ topic was “continental drift,” trying to explain geologic observations from the last 100 years. The hypotheses were bizarre, but all tried to explain Earth’s offering up new landscape (ocean floor spreading) without expanding the globe. He summed it up simply: We needed a mechanism for generating new oceanic crust at ocean ridges while concurrently destroying old oceanic crust, plus acquired sediment, in ocean trenches. He sketched it out with chalk. 

One important piece of evidence was abundant guyots (named by Hess for geologist Arnold Guyot, the namesake for Guyot Hall). Guyots are flat-topped (eroded at sea level) volcanic seamounts ranging from near sea level to now more than 5,000 feet below sea level; some are found near trenches. Hess discovered them while plying the Pacific during World War II. The guyots led him to postulate that they would be consumed as the trench consumed the descending oceanic crust, including guyots, thereby conserving the volume of Earth. He was correct. 

In 1963, a three-page article by Frederick Vine and Drummond Matthews in Nature revealed the mechanism, a unifying paradigm of the evolution of the crust. Plate tectonics was born. Hess saw it all and shared it with our class in 1962. He lived to see the new paradigm fleshed out, but not nearly long enough.

Editor’s note: The writer is a professor of earth and climate sciences, emeritus, at the University of Maine.