Marie Tharp

Marie Tharp was born on July 30, 1920 in Ypsilanti, Michigan, the only child of Bertha Louise Tharp, a German and Latin teacher, and William Edgar Tharp, a soil surveyor for the United States Department of Agriculture.[3] She often accompanied her father on his field work, which gave her an early introduction to mapmaking. Despite this, she had no interest in pursuing a career in field work as during that time this was understood to be men's work.

Due to the nature of William Tharp's work, the family moved constantly until he retired in 1931. At that point Marie had attended over a dozen public schools in Alabama, Iowa, Michigan and Indiana, which made it difficult for her to establish friendships.[3] Her mother, who died when Marie was 15,[4] was her closest female acquaintance.[3] A full school year in Florence, Alabama, was particularly influential for her. There, she attended a class called Current Science, in which she learned about contemporary scientists and the research projects they were working on. In addition, she got the chance to undertake school field trips on weekends to study trees and rocks.[4]

After his retirement, William Tharp and the rest of the family moved to a farm in Bellefontaine, Ohio where, shortly after, Marie graduated from high school.[1] Influenced by her mother, a teacher, she took a year off before going to college; after graduating, she too planned to become a teacher. Staying on the farm to help after her mother’s death in 1936, Marie later matriculated in college.[5] Advised by her father to choose a subject of study that she not only loved, but also would provide her with a career and financial security, Tharp graduated from Ohio University in 1943 with bachelor's degrees in English and music and four minors.

After the attack on Pearl Harbour by the Japanese army, many young men dropped out of schools and universities to join the armed forces.[6] World War II hence meant more women were being recruited into professions like petroleum geology, hitherto largely restricted to men. Having taken a geology class at Ohio, Tharp was recruited to the University of Michigan at Ann Arbor's petroleum geology program, where she completed a master's degree.[7] Tharp's leap into a career in earth sciences is extraordinary given that women have long been discouraged from working in the field — women obtained fewer than 4% of all earth sciences doctorates at this time.[8]

She took a job at the Stanolind Oil company in Tulsa, Oklahoma, as a junior geologist, but soon found it unsatisfying. At that time, in fact, women were not allowed to go on field trips to look for oil and gas. She was therefore confined to the office, where her duties were to collect the maps and data for the men going in the field.[6] While still working as a geologist for the Stanolind Oil company, Tharp enrolled in the faculty of mathematics at the University of Tulsa, obtaining her second BSc.[6]

By 1948, Tharp had spent four years in Tulsa and was looking for her next career step. She moved to New York City and initially sought work at the American Museum of Natural History, but after learning how time-consuming paleontological research was, she looked for positions at Columbia University.[9] She eventually found drafting work with Maurice Ewing, the founder of the Lamont Geological Observatory (now the Lamont-Doherty Earth Observatory). Curiously, when interviewed for the job, Tharp did not mention she had a master's degree in geology.[10] Tharp was one of the first women to work at the Lamont Geological Observatory.

While there, she met Bruce Heezen, and in early work together they used photographic data to locate downed military aircraft from World War II.[11] Eventually she worked for Heezen exclusively, plotting the ocean floor.[9] Tharp was employed and continuously promoted from 1952 to 1968, when her position was cut and moved to grant-funded status due to lab politics involving Heezen (she remained in a grant-funded position until Heezen's death in 1977). Because of the Cold War, the U.S. government forbade seafloor maps to be published, for fear that Soviet submarines could use them.[6]

For the first 18 years of their collaboration, Heezen collected bathymetric data aboard the research ship, the Vema, while Tharp drew maps from that data, since women were still excluded from working aboard ship at that time. Although sexism barred her from conducting research at sea in her early career, she was later able to join a 1968 data-collection expedition. She independently used data collected from the Woods Hole Oceanographic Institution's research ship Atlantis, and seismographic data from undersea earthquakes. Her work with Heezen represented the first systematic attempt to map the entire ocean floor.

Before the early 1950s, scientists knew very little about the structure of the ocean floor. Though studying geology on land was cheaper and easier, understanding the structure of the entire earth could not be accomplished without knowledge of the structure and evolution of the seafloor.

In 1952, Tharp painstakingly aligned sounding profiles from Atlantis, acquired during 1946 - 1952, and one profile from the Naval ship Stewart acquired during 1921. She created a total of approximately six profiles stretching west-to-east across the North Atlantic. From these profiles, she was able to examine the bathymetry of the northern sections of the Mid-Atlantic Ridge. Tharp identified an aligned, v-shaped structure running continuously through the axis of the ridge and believed that it may be a rift valley.[9][12] She believed that the rift valley formed by the oceanic surface being pulled apart.[9] Heezen was initially unconvinced as the idea would have supported continental drift, then a controversial theory. At the time many scientists including Heezen believed that continental drift was impossible. Instead, for a time, he favored the expanding Earth hypothesis,[13][14] (now infamously) dismissing her explanation as "girl talk".[15]

Heezen soon hired Howard Foster to plot the location of earthquake epicenters in the oceans for a project relating large-scale turbidity currents to undersea earthquakes. The creation of this earthquake epicenter map proved to be a useful secondary dataset for examining the bathymetry of the Mid-Atlantic Ridge. When Foster's map of earthquake epicenters was overlain with Tharp's profile of the Mid-Atlantic Ridge it became clear that the location of these earthquakes aligned with Tharp's rift valley. After putting together these two datasets, Tharp became convinced that a rift valley did in fact exist within the crest of the Mid-Atlantic Ridge.[9] It was only after seeing that the location of earthquake epicenters aligned with Tharp's rift valley that Heezen accepted her hypothesis and turned to the alternative theories of plate tectonics and continental drift.[16][17]

Painting of the Mid-Ocean Ridge by Heinrich Berann (1977) based on the scientific profiles of Marie Tharp and Bruce Heezen

Tharp and Heezen published their first physiographic map of the North Atlantic in 1957.[9] Still, Tharp's name does not appear on any of the major papers on plate tectonics that he and others published between 1959 and 1963. Tharp continued working with graduate student assistants to further map the extent of the central rift valley. Tharp identified that the rift valley extended along with the Mid-Atlantic Ridge into the South Atlantic,[9] and found a similar valley structure in the Indian Ocean, Arabian Sea, Red Sea, and Gulf of Aden, suggesting the presence of a global oceanic rift zone.[18] Subsequently, in collaboration with the Austrian landscape painter Heinrich Berann, Tharp and Heezen realized their map of the entire ocean floor, which was published in 1977 by National Geographic under the title of The World Ocean Floor.[6] Although later recognized and attributed to for her work today on the Mid-Atlantic Ridge, it was Heezen, who at the time in 1956, put out and received credit for the discovery that was made.

After Heezen's death, Tharp continued to serve on the faculty of Columbia University until 1983, after which she operated a map-distribution business in South Nyack during her retirement.[19] Tharp donated her map collection and notes to the Map and Geography Division of the Library of Congress in 1995.[20] In 1997, Tharp received double honors from the Library of Congress, which named her one of the four greatest cartographers of the 20th century and included her work in an exhibit in the 100th-anniversary celebration of its Geography and Map Division.[21] In 2001, Tharp was awarded the first annual Lamont-Doherty Heritage Award at her home institution for her life's work as a pioneer of oceanography.[2] Tharp died of cancer in Nyack, New York on August 23, 2006 at the age of 86.[22]

In 1948, she married David Flanagan and moved with him to New York. They were divorced by 1952.[23]

Like many women scientists of her era, Marie Tharp was recognized mainly later in life. Her awards include:

• 1978 - National Geographic Society’s Hubbard Medal
• 1996 - Society of Woman Geographers Outstanding Achievement Award
• 1999 - Woods Holes Oceanographic Institution’s Mary Sears Woman Pioneer in Oceanography Award
• 2001 - Lamont–Doherty Earth Observatory Heritage Award[24]

Tharp was recognized in 1997 by the Library of Congress as one of the four greatest cartographers of the 20th century.[25] The position of Marie Tharp Lamont Research Professor was created in her honor.[26]

• Tharp, Marie; Heezen, Bruce C.; Ewing, Maurice (1959). The floors of the oceans: I. The North Atlantic. 65. Geological Society of America. doi:10.1130/SPE65-p1.
• Heezen, B C; Bunce, Elizabeth T; Hersey, J B; Tharp, Marie (1964). "Chain and Romanche fracture zones". Deep-Sea Research and Oceanographic Abstracts. 11 (1): 11–33. Bibcode:1964DSROA..11...11H. doi:10.1016/0011-7471(64)91079-4.
• Heezen, B C; Tharp, Marie (1965). "Tectonic fabric of the atlantic and indian oceans and continental drift". Philosophical Transactions of the Royal Society of London A. 258 (1088): 90–106. Bibcode:1965RSPTA.258...90H. doi:10.1098/rsta.1965.0024. S2CID 121476006.
• Tharp, Marie; Friedman, Gerald M (2002). "Mapping the world ocean floor". Northeastern Geology and Environmental Sciences. 24 (2): 142–149..

• C250 Celebrates 250 Columbians Ahead of Their Time: Entry on Marie Tharp.
• Woods Hole Oceeanographic Institution. "Marie Tharp Honored at Women Pioneers Seminar."
• The Earth Institute at Columbia University. "Mapping Methodology Examples (North Atlantic)."
• The Earth Institute at Columbia University. "Marie Tharp, Pioneering Mapmaker of the Ocean Floor, Dies." Earth Institute News, August 23, 2006.
• Nelson, Valerie. "Marie Tharp, 86; Pioneering Maps Altered Views on Seafloor Geology." The Los Angeles Times, September 4, 2006.
• Hall, Stephen S. "The Contrary Map Maker" The New York Times Magazine, December 31, 2006.
• Felt, Hali (2012). Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor. New York: Henry Holt and Co. ISBN 9780805092158.
• Doel, Ronald (1970–1980). "Tharp, Marie". Dictionary of Scientific Biography. 25. New York: Charles Scribner's Sons. pp. 29–31. ISBN 978-0-684-10114-9.
• James, Josie (2020), "Marie's Ocean: Marie Tharp Maps the Mountains Under the Sea". Henry Holt and Co. (BYR), Holt Books for Young Readers. ISBN 9781250214737

• Marie Tharp at Columbia University