Portrait of Harry Hammond Hess
. Historical USGS photograph of Hess in naval uniform. The Commons file page lists the photographer as unknown and identifies the image as public domain USGS material. Source. Articles by others on the same topic
Harry Hammond Hess (1906–1969) was an American geologist and a major figure in the development of the theory of plate tectonics. He is best known for his contributions to the understanding of seafloor spreading, a key concept in the theory of plate tectonics which explains how new oceanic crust is formed at mid-ocean ridges and how it subsequently moves away from the ridges, causing continental drift.