By Emma Jamrin
Published in 1957, this is the first scientific, physiographic map of the Atlantic Ocean Floor, drafted by Marie Tharp from echo-sounding data. The map focuses on the floor of the Atlantic Ocean and the surrounding basin. Landmasses, including the majority of eastern North America, are depicted in yellow, and underwater areas in blue. Revolutionarily illustrated is the varied topography, which debunked the common belief that the ocean floor was flat.
The Mid-Atlantic Ridge, with a rift valley at its center, extends from the top to the bottom of the map. Tharp, in addition to mapping the ocean floor, gathered evidence of seismic activity at the location of the Ridge, supporting Alfred Wegener’s theory of continental drift. At the time, allegiance to the theory of continental drift was so heavily disputed that it could cost a budding geologist their career. In fact, Heezen disregarded Tharp’s initial recognition of the correlation between the mid-Atlantic Ridge and the rift as “girl talk.”
From 1920 to 1970, only 4% of all earth science doctorates were pursued by women. But, due to an absence of male geologists lost to the draft, Marie Tharp was able to pursue her passion and was recruited into the University of Michigan’s geology program during WWII. After moving to New York, she began her research with Heezen at the Columbia University Geology Department. Heezen collected bathymetric data at sea, while Tharp reviewed and translated the data into her revered physiographic maps at the university. Women were banned from expeditions on research vessels until 1959, and Tharp first went on one in 1968.
Tharp earned many awards for her maps and is a revered member of the cartographic community. The Geography and Map Division of the Library of Congress holds Tharp’s trailblazing work, amounting to 40,000+ items. Today, the mid-Atlantic Ridge is considered one of Earth’s most significant physical features.
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