Marie Tharp

Born on 30 July 1920 in Ypsilanti, Michigan, Marie Tharp was a geologist and oceanographic cartographer who helped create the first map of the ocean floor. After earning bachelor’s degrees in English and music at Ohio University in 1943, Tharp enrolled at the University of Michigan, where she had been recruited into a petroleum geology program because of the dearth of male students during World War II. Upon completion of her master’s degree in 1944, she worked a brief stint with an oil company in Tulsa, Oklahoma, before enrolling at Tulsa University to pursue a BS in mathematics. In 1948 she moved to New York, where she accepted a position at Columbia University’s Lamont Geological Laboratory (now the Lamont–Doherty Earth Observatory). There she embarked on a vast project mapping Earth’s ocean floor. Because women at that time were not allowed onboard research vessels, Tharp crunched numbers and processed raw data collected by male scientists, including geologist Bruce Heezen, with whom she collaborated for almost three decades. Tharp determined that the ocean floor comprised mountains and canyons that rivaled those on the continents, and she discovered the mid-ocean ridge, or oceanic ridge, a 65 000-kilometer global underwater mountain range that is Earth’s largest physical feature. Her discovery provided evidence of seafloor spreading and continental drift, and supported the then-controversial theory of plate tectonics. Despite Tharp’s important contributions to the field, most of the credit went to her male colleagues. Years later her achievements would be recognized by several important awards, including the 1978 National Geographic Society’s Hubbard Medal, the 1996 Society of Women Geographers Outstanding Achievement Award, the 1999 Woods Hole Oceanographic Institution’s Mary Sears Woman Pioneer in Oceanography Award, and the very first Lamont–Doherty Earth Observatory Heritage Award, in 2001. In 1997 the Library of Congress named Tharp one of the four outstanding cartographers of the 20th century. She died of cancer in 2006 at age 86. (Photo credit: Lamont–Doherty Earth Observatory, Columbia University)

Date in History: 30 July 1920