Seafloor Mapping

The first detailed map of the ocean’s bottom in 1957 helped revolutionize our understanding of the geology of the seafloor—and contributed directly to the development of the theory of plate tectonics.

With the importance of submarines to modern naval warfare firmly established during World War II—only heightened with the impending development of even more deadly and deeper-diving nuclear submarines in the early 1950s—the U.S. Navy was keenly interested in acquiring accurate maps of the world’s oceans. After the war, the Office of Naval Research (ONR) funded efforts at the Woods Hole Oceanographic Institute, the Scripps Institution of Oceanography, and especially the Lamont Geological Observatory at Columbia University to collect the sounding data that eventually would be used to create such maps.

Early attempts to map the seafloor had been hampered by crude technology that allowed only limited areas to be surveyed for depth. The development of echolocation (and later sonar) beginning in World War I allowed for much larger areas of the ocean to be surveyed more efficiently and quickly than before. The German Meteor expedition in the 1920s was superseded substantially by concerted action by the United States in the late 1940s and early 1950s as Cold War concerns pushed research dollars into the oceanographic sciences.

Bruce Heezen and Marie Tharp at Lamont combined this data with soundings from commercial transatlantic telephone cable laying operations to create, in 1957, a map of the North Atlantic that was the first to incorporate everything that had been gathered about the seafloor since the war. Notably, it was the first map to shown in detail the so-called Mid-Atlantic Ridge. Originally thought to be evidence of an expanding Earth, it would later lead directly to the concept of seafloor spreading—which would become a central component of the theory of plate tectonics developed in the 1960s.

Bruce Heezen and Marie Tharp’s map of the ocean floor radically changed understanding of both the undersea realm and the geology of the Earth.Bruce Heezen and Marie Tharp’s map of the ocean floor radically changed understanding of both the undersea realm and the geology of the Earth.
(Photo courtesy of Columbia University)

* Some pages on this website provide links which require a plug in to view.