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Marie Tharp, the woman who discovered the Earth’s backbone

Mid-Atlantic Ridge

Marie Tharp was born July 30, 1920 in Ypsilanti, Michigan. As a young girl she followed her father, a soil surveyor for the United States Department of Agriculture, into the field.  However, she also loved to read and actually wanted to study literature at St. John’s College in Annapolis, but as women were not admitted there at that time, she went to Ohio University, where she graduated in 1943.

The Second World War dramatically changed the situation for women in the United States – the nation needed highly educated replacements for the men who went to war, so women were encouraged to obtain degrees in ‘manly’ disciplines like science and technology. Marie enrolled in a petroleum geology programme, becoming one of the first ‘Petroleum Geology Girls’ when she graduated in 1944. She worked for a short time in the petroleum industry, but found the work unrewarding and decided to resume her studies at Tulsa University. In 1948 she graduated in mathematics and found work at the Lamont Geological Laboratory of Columbia University.

During the Cold War money was available for various geological projects such as studying and mapping the ocean floor, the battlefield for a possible future war with submarines. Marie started a prolific collaboration with geologist Bruce Heezen (1924 -1977), a specialist in seismic and topographic data obtained from the sea floor. As a woman, Marie was not allowed on board the research vessels collecting the raw data, so she began to calculate, interpret and visualize the data obtained when Heezen went to the sea. She co-authored a book and various papers with Heezen, however her work was often undervalued, perhaps because bureaucracy and financial difficulties in her department sometimes forced Marie to work from home.

Between 1959 until the death of Heezen in 1977, Marie worked tirelessly on various maps that would depict the still unknown topography of the oceanic basins – the results were astounding. The ocean floor was not a flat plain of mud, as previously imagined, but displayed mountains, ridges and canyons, sometimes larger and deeper than any feature found on the continents. The most impressive feature however was a chain of mountains that encircled the world, dividing all the large oceans in half. Tharp and Heezen had discovered the backbone of Earth: the Mid-Ocean Ridges.


BARTON, C. (2002): Marie Tharp, oceanographic cartographer, and her contributions to the revolution in the Earth sciences. In OLDROYD, D.R. (ed.) The Earth Inside and Out: Some Major Contributions to Geology in the Twentieth Century. Geological Society Special Publications 192, London: 215-228.

HEEZEN, B.C. & HOLLISTER, C. D. (1971): The face of the deep. Oxford Univ. Press, New York, London, and Toronto: 659.

This article is thanks to David Bressan, a freelance geologist interested in the history and the development of geological concepts through time.

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