Mary Tharp exploded He came to New York from the Midwest in 1948 in search of work. Twenty-nine years old and armed with degrees in geology and mathematics, Tharp inquired in Columbia, where she was told to contact Maurice Ewing, director of the new Lamont Geological Observatory, now the Lamont-Doherty Earth Observatory (LDEO). Ewing was not known to have much respect for scientists, and he was unsure what to do with Tharp. Finally he said, “Can you formulate?”
Tharp had drawn maps in graduate school, and her father had drawn soil survey maps for the government. Mapping was part of her DNA. Hired by Ewing, she became an assistant to a graduate student, Bruce Hazen ’57GSAS. Over the next decade, the three scientists collaborated and collided, shaking up the field of geophysics and reshaping our understanding of planetary mechanics.
Hazen worked on research ships in the North Atlantic, sampling the seafloor using sonar. At the time, women were not welcome aboard these ships, so Tharp stood at drafting tables in Lamont Hall and plotted the data, using tens of thousands of soundings made by Hazen and others to discern minute features of the ocean floor. Six west-to-east elevation profiles of the North Atlantic seafloor at different latitudes were completed. All profiles represent the Mid-Atlantic Ridge, a north-south undersea mountain range first discovered by oceanographer Matthew Fontaine-Maury in 1853.
Tharp then noticed something strange: While each segment had its own distinct topography, all six bore the same V-shaped indentation that ran down the middle of the mountain range. Tharp thought it might be a rift valley, where magma had erupted, splitting the ridge in two and pushing it apart.
This was a potential bombshell. A rift valley would support the theory of continental drift, which holds that all continents were once a single land mass, and have been separate ever since. This idea, proposed by German geophysicist Alfred Wegener in 1912, was widely ridiculed by scientists; Ewing was strongly against drift. “If you brought it up, people looked at you funny,” says LDEO researcher Bill Ryan ’71GSAS, who had an office next to Tharp’s. “Mary Tharp was more open to continental drift.” At the time, Hazen sided with Ewing, in effect dismissing Rift Valley as “girl talk.” But Tharp was undeterred.
Meanwhile, Hazen took on a project for Bell Labs, mapping the foci of offshore earthquakes. He found that the epicenters of these earthquakes were located not only along the Mid-Atlantic Ridge, but also within the speculative Tharp Valley. By 1953, Hazen was convinced that a continuous underwater mountain range wrapped around the planet like a baseball line, and that a central valley ran through it. Hazen came up with the idea of a rift valley.
For Ewing, any such claim is sacrilegious. But in 1959, Jacques Cousteau, a Rift Valley skeptic, crossed the Atlantic dragging a submerged film camera that surprisingly revealed the cliffs that surround the Tharp Valley. In the same year, Tharp, Hazen, and Ewing published the first map of the North Atlantic seafloor: an overhead view of the terrain as it would appear without water.
In its varied terrain of mountains, hills and valleys, the map was revealing: many had assumed the sea floor to be generally flat. But despite the map’s success, a long-standing academic dispute between Ewing and Hazen intensified in the 1960s, threatening future cartographic projects. Ewing couldn’t fire Hazen, who was in charge, so he fired Tharp instead. But Hazen, with funding from the Navy, continued his research while Tharp worked from home, supported by a Hazen grant.
Tharp and Heisen produced further maps, culminating in a 1977 panorama of the entire ocean floor, drawn by artist Heinrich Beran. Hazen died that year at the age of fifty-three.
Tharp died in 2006 at the age of eighty-six. Its achievements are profound: its maps have become classics, and its rift valley gave rise to the theory of plate tectonics, which holds that the Earth’s crust and mantle are divided into sections that fit together like puzzle pieces. She reconciled with Columbia after Ewing left in 1970 and later stated that she had no regrets. “I was lucky to have a very interesting job,” she once said. “Creating the rift valley and the mid-ocean ridge that went all the way around the world for forty thousand miles – that was a big deal.”
US Navy agrees. Earlier this year, Navy Secretary Carlos del Toro announced the name of the survey ship Mori has been changed to Mary Tharp. History indicates that Tharp did not board a research vessel until 1968. And now, finally, her ship has arrived.