Marie Tharp was an American geologist and oceanographic cartographer. In 1944 she earned a master’s degree in geology from the University of Michigan, and later a second bachelor’s degree in mathematics from the University of Tulsa. Tharp was one of the first women to work at Columbia University’s Lamont Geological Observatory. There she met Bruce Heezen. They worked together for over 25 years plotting the ocean floor. Since women were barred from working on ships at that time, Heezen would collect bathymetric data aboard research ships while Tharp drew maps from that data. At that time the ocean floor was thought to be mostly flat and featureless but her drawings revealed that the seafloor is instead covered in canyons, ridges, and mountains. Tharp and Heezen published the the first map of the Atlantic in 1957, which revealed the 40,000-mile-long Mid-Atlantic Ridge. In 1977, they published the first complete world map of the ocean floors. Their work helped to prove the theory of plate tectonics, a controversial idea at that time. Tharp was recognized in 1997 by the Library of Congress as one of the four greatest cartographers of the 20th century.
