Marie Tharp

Some scientists find their life’s passion exploring the vast unknowns of the galaxies; others, like this week’s WiSE Wednesday honoree, Marie Tharp, find themselves drawn to mysteries at the bottom of the ocean. Working with a fellow geologist, Bruce Heezen, Tharp created the first scientific map to cover the entire ocean floor, and, in doing so, discovered a deep rift in a long chain of underwater mountains called the Mid-Atlantic Ridge. Tharp meticulously mapped this rift valley and interpreted it as strong evidence that the continents became separated by the movement of tectonic plates in earth’s outer layers – as the plates move apart, magma rises from deeper layers, leading to the formation of mountains like those composing the Mid-Atlantic Ridge. Tharp’s map was at first widely disputed because, at the time (the 1950s), the theory of continental drift was highly controversial. In fact, Heezen himself initially dismissed Tharp’s support of a continental drift hypothesis as “girl talk.” Nevertheless, Sharp persisted in analyzing as much information on the ocean’s floor as she could get her hands on (she initially wasn’t allowed on data collecting expositions because she was a woman, so she had to depend on data Heezen and others collected). As Heezen and other geographers engaged in lively, often heated, debates, Tharp worked tirelessly in the background. The more she analyzed the data, the stronger her conclusions became, and Heezen and the rest of the scientific community eventually came around to accepting the continental drift theory, propped up by the confirmation of Tharp’s work by National Geographic-funded explorations.

Tharp was born in Michigan in 1920 and received a degree in English from Ohio University in 1943, followed by a Master’s in petroleum geology from the University of Michigan. She started a job in micropaleontology in Oklahoma, but found the work tedious so she took night classes to earn another degree in mathematics. Three degrees in hand, she took a job at Columbia, where she began her longtime collaboration with Heezen and performed her ground-breaking work. Despite remaining largely in the background through much of her career, Tharp eventually received recognition for her findings - the Library of Congress named her as one of the four greatest cartographers of the 20th century; Google Earth added a layer to view her historical map; and she received Columbia’s first annual Lamont-Doherty Heritage Award. Tharp died of cancer in 2006 at the age of 86, but not before she was finally given opportunities to go on data-gathering explorations.

Photo credit: Bruce Gilbert

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