Resurfacing the ocean floor

The theory of plate tectonics is considered one of the true paradigm shifts in the natural sciences. It explains large-scale geologic changes by motions of the Earth’s lithosphere, which is made up of seven major tectonic plates and many minor ones.

Marie Tharp 1961

Marie Tharp at Lamont, ca. 1961 (Lamont-Doherty Earth Observatory)

The theory built on the ideas of continental drift developed in the early 1900s, but only entered mainstream scientific thought over half a century later.  Among those who marshalled plate tectonics out of the realm of crackpot were well-known names such as Wegener, Ewing, Heezen, Hess, Wilson.  A name that is often relegated to a footnote if not overlooked altogether is Tharp.

Marie Tharp (1920-2006) was born in Michigan, the daughter of a soil surveyor for the U.S. Department of Agriculture and a teacher.  Independent and curious about the world around her, she earned a string of degrees in English and music (Ohio University), geology (University of Michigan) and mathematics (University of Tulsa).  Tharp moved to New York in 1948 and convinced Maurice “Doc” Ewing to hire her as a technical assistant (an overqualified one, to be sure) at the newly founded Lamont Geological Laboratory, now Lamont-Doherty Earth Observatory, at Columbia University.

At Lamont, Tharp began a lifelong collaboration with Bruce Heezen that transformed our geophysical understanding of the Earth.  Together, they mapped the topography of the ocean floor using data that Ewing, Heezen and other colleagues had collected on cruises aboard research vessels (at the time, women were not allowed in the field). Tharp relied on her geological background and drafting skills to stitch together sonar soundings of ocean depth into astoundingly detailed charts of the seafloor, the first of their kind, in the process discovering in 1952 a rift valley along the underwater mountain range bisecting the Atlantic Ocean.  Heezen’s initial reaction was,  “Girl talk. It cannot be. It looks too much like continental drift.”  It took Tharp months to convince him of her discovery, and the two of them years to convince their peers, but this rift – a seam in the Earth where new crust forms as the tectonic plates on either side move steadily apart – paved the way for the acceptance of plate tectonics.

seafloor map

In 1977, Tharp and Heezen’s pioneering work was transformed by Austrian landscape artist Heinrich Berann into a masterpiece of cartography, a depiction of the seafloor that is still considered one of the most beautiful maps ever created. (World Ocean Floor Panorama, Marie Tharp and Bruce C. Heezen, 1977)

Tharp lived in times when women had scant chance of being recognized for their achievements. Only recently has she emerged from relative obscurity, receiving honours from the U.S. Library of Congress Geography and Map division in 1998 and the Woods Hole Oceanographic Institution in 1999, as well as the Lamont-Doherty Heritage Award in 2001.  In 2005, the Marie Tharp Fellowship programme (now institutionalized at Lamont-Doherty Earth Observatory) was established to promote women in the earth sciences.

Upon her death of cancer in 2006, the New York Times Magazine published a piece about Tharp that captured the interest and imagination of science writer Hali Felt. Driven to restore Tharp’s life and work to the world’s attention, Felt wrote Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor (Henry Holt and Co., 2012).

Information on eligibility and how to apply to the Marie Tharp Fellowship is available at the programme website.  Note that the Fellowship is on hiatus this year (2013-2014) because of an internal reorganization within the Director’s Office at Lamont.


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Camille Li

I am an associate professor of atmospheric sciences at the Geophysical Institute, University of Bergen. My research is concerned with the large scale dynamics of the atmosphere and how its interactions with other components of the climate system (ocean, sea ice, land ice) drive climate variability over a wide range of time scales.

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