Tharp, Marie (1920-2006), an American geologist and cartographer, is known for her pioneering work in mapping the ocean floor. Cartography is the making and studying of maps and charts. The ocean floor makes up most of Earth’s solid surface. Yet it remained largely unmapped before Tharp’s time. 
Tharp was born on July 30, 1920, in Ypsilanti, Michigan. She studied music and English at Ohio University in Athens, graduating in 1943. She then studied geology, receiving a master’s degree at the University of Michigan in Ann Arbor in 1944. At the time, the school’s geology department, like many others, was generally limited to men. But Tharp was able to enroll because many men were off serving in the military during World War II (1939-1945). After graduating, she began work at an oil company in Tulsa, Oklahoma. Women were not permitted to do geological work in the field, so Tharp was limited to producing maps from field data collected by male colleagues. She also enrolled in the mathematics program at the University of Tulsa , where she earned another degree in 1948.
Tharp took a research position in geology at Columbia University in New York City. Working with an American geologist named Bruce Heezen, Tharp analyzed data on the ocean floor collected by research ships. Women were not allowed on the research vessels, so Tharp produced maps from data collected by Heezen and others. In 1977, Tharp and Heezen produced the then most complete map of Earth’s ocean floor, called the World Ocean Floor Panorama. The map is still widely used today.
Before Tharp made her maps, most people thought of the Earth’s ocean floor as a flat, featureless, plain of mud. Tharp and her colleagues discovered mountains, ridges, and canyons, with some larger and deeper than any found on land. Tharp and Heezen also discovered a system of undersea mountains that runs throughout the world ocean in a continuous chain. These mid-ocean ridges wind around the entire planet. Tharp left Columbia University in 1983 and went on to operate a map-distribution business. She died on Aug. 23, 2006.
