Marie Tharp

Marie Tharp was an American geologist and cartographer who, working with the oceanographer Bruce Heezen at Columbia University, created the first detailed, systematic maps of the floor of the world's oceans. Because women were barred at the time from joining the research ships that collected the underlying sonar depth data, Tharp worked from the resulting soundings on shore, carefully plotting and interpreting them, and in doing so identified a long, continuous rift valley running down the center of the Mid-Atlantic Ridge, evidence of active seafloor spreading. Her interpretation of the data was initially dismissed by Heezen as girl talk, but further evidence, including a close match between Tharp's rift valley and the pattern of earthquake locations along the ridge, soon confirmed her finding and made it a key piece of supporting evidence for the then-controversial theories of continental drift and plate tectonics. Tharp and Heezen went on to publish comprehensive physiographic maps of the entire ocean floor, first published in the 1960s and 1970s, work that fundamentally changed scientific understanding of the seafloor's structure and history.