[2] Tharp's discovery of the Mid-Atlantic Ridge caused a paradigm shift in earth science that led to the acceptance of the theories of plate tectonics and continental drift.

At that point, Marie had attended over 17[8] public schools in Alabama, Iowa, Michigan and Indiana, which made it difficult for her to establish friendships.

[9] After her father's retirement, Marie Tharp moved to a farm in Bellefontaine, Ohio, where she graduated from the local high school.

After the Japanese attack on Pearl Harbor, many young men left schools and universities to join the armed forces.

[2][7] While still working as a geologist for the Stanolind Oil company, Tharp enrolled in the faculty of mathematics at the University of Tulsa, obtaining her second BSc.

While there, she met Bruce Heezen, and in early work together, they used photographic data to locate downed military aircraft from World War II.

As early as the mid-19th century, a submarine mountain range in the Atlantic had been roughly outlined by John Murray and Johan Hjort.

Marie Tharp also discovered the rift valley on her more precise graphical representations of the Mid-Atlantic Ridge, which were based on new measurement data obtained with the echo sounder.

Tharp identified an aligned, v-shaped structure running continuously through the axis of the ridge and believed that it might be a rift valley[12][19] formed by the oceanic surface being pulled apart.

The creation of this earthquake epicenter map proved to be a useful secondary dataset for examining the bathymetry of the Mid-Atlantic Ridge.

After putting together these two datasets, Tharp became convinced that a rift valley existed within the crest of the Mid-Atlantic Ridge.

[12] It was only after seeing that the location of earthquake epicenters aligned with Tharp's rift valley that Heezen accepted her hypothesis and turned to the alternative theories of plate tectonics and continental drift.

[23][24] Because of the Cold War, the U.S. government forbade topographic seafloor maps to be published for fear that Soviet submarines could use them.

Tharp continued working with graduate student assistants to further map the extent of the central rift valley.

Tharp demonstrated that the rift valley extended along with the Mid-Atlantic Ridge into the South Atlantic,[12] and found a similar valley structure in the Indian Ocean, Arabian Sea, Red Sea, and Gulf of Aden, suggesting the presence of a global oceanic rift zone.

After Heezen's death, Tharp continued to serve on the faculty of Columbia University until 1983, after which she operated a map-distribution business in South Nyack during her retirement.

"[37] She was animated in "The Lost Worlds of Planet Earth", the ninth episode of Neil deGrasse Tyson's Cosmos: A Spacetime Odyssey, and voiced by actress Amanda Seyfried.