Celebrating Marie Tharp: The Queen of the Oceans!

Apeksha Srivastava and Aniruddha Mukherjee

See through the sea!
  July 30, 2020, marked the 100th birth anniversary of the very inspirational Marie Tharp, the woman who 'decoded' the oceans. While several other scientists remain at the forefront of academic media, not many people know about the woman who showed us, for the first time, that the ocean bottom has a range of geographical features, similar to what we see on land. Before the early 1950s, the world knew very little about the ocean floor structure. It was her revolutionary work that not only opened doors to previously unknown and amazing terrain of the ocean floor, but also made it possible for us to understand our planet better. Marie Tharp was one of the creators of the first detailed map of the Atlantic Ocean floor, and she definitely did not stop just there.



A Series of ‘Fortunate’ Events

Born in Ypsilanti (Michigan) in 1920, Marie Tharp was the daughter of William Tharp, a surveyor who mapped soils for the United States Department of Agriculture. A possible reason that influenced her growing interest in science was that, as a child, Marie loved to accompany her father during his fieldwork. Her school trips to explore nature seemed to add fuel to the fire of her scientific curiosity as well. However, since women were not encouraged to work in the ‘male-dominated’ scientific fields at that time, Tharp never even considered taking up science for her bachelor’s degree. She graduated from Ohio University with English and Music instead. The 1941 attack on Pearl Harbor that led the U.S. to enter World War II was the turning point in Marie Tharp’s scientific career. During this time, women were being recruited to fill many ‘men-only’ positions because men went to war. The University of Michigan, thus, opened its doors to girls, promising them jobs in the petroleum industry if they earned a degree in geology. Studying the earth resulted in Tharp getting a job at the Stanolind Oil and Gas Company, Oklahoma. The deep-rooted gender bias in society resulted in her collecting information and maps to assist men, the only ones allowed to go for fieldwork at that time. In the face of all challenges, Tharp completed her bachelor’s in Mathematics while working here. One thing led to another, and she became one of the first women to work at the Lamont Geological Observatory (now known as the Lamont-Doherty Earth Observatory at Columbia University) in 1948.

Bringing Oceans to Life

During her time at Lamont Geological Observatory, Tharp started working with Bruce Charles Heezen, another American geologist, to locate drowned military aircraft from the war. With time, they began to map the ocean floor. For about 18 years, Tharp drew sketches, using data that Heezen collected, aboard the ship. The woman, who unlocked the crucial mysteries of the ocean floor, could not set foot on ships, owing to the sexism that did not ‘allow’ women to do so.

After marking the locations the ship had traveled to, Tharp read the depth at each location using the sonar technique. Sonar uses sound waves to detect objects on or under the surface of water. It helped her to plot the ocean floor depths against the distance traveled.. Tharp’s observations across the North Atlantic brought up something unexpected. Her calculations indicated a huge cleft in the center of the ocean. She suggested that it was a rift valley: a linear lowland between highlands created by pulling the earth’s outermost layer apart. Until then, it was something known to exist only on land. Heezen accepted her hypothesis as justified only after confirming that the location of earthquake epicenters (points where earthquakes originate), as mapped by another researcher, aligned with her ‘proposed’ rift valley. This revolutionary discovery was crucial for major developments in the geological sciences. For example, the theory of plate tectonics, which states that the earth’s outermost layer (crust) is separated into plates that move over the molten upper-mantle layer, or the theory of continental drift, stating that the planet’s continents have moved across the ocean bed over time, gained momentum within the scientific community with this discovery.

Seeing is Believing

In order to present their findings credibly before a much wider audience, Tharp and Heezen decided to draw physiographic maps of the ocean floor. These showed the terrain as it would look from a low-flying plane, capturing the varied features of the ocean floor. These maps helped to publish their work too, as the U.S. Navy’s contour maps were classified. With time, Tharp used information obtained from 30 cruises to establish that the rift valley extended into the South Atlantic as well. The Indian Ocean, Red Sea, Arabian Sea, and the Gulf of Aden disclosed similar features, proving that the mid-ocean rift system extended throughout the earth! We can understand this rift system as a range of underwater volcanoes wrapping around the globe like seams on a baseball.

Meanwhile, scientist and explorer Jacques Cousteau, doubtful of their claims, set sail into the Atlantic Ocean with an underwater camera, aiming to prove Tharp and Heezen wrong. But, his photos and videos clearly captured the rift valley, proving its existence. Cousteau displayed his photographs at the First International Oceanographic Congress in 1959, thereby convincing many people of Tharp’s hypothesis. The North Atlantic physiographic map was first published in 1956, revealing that the ocean floor consists of features like valleys and mountains. In 1959, The Geological Society of America reprinted it. Then followed the publishing of the South Atlantic diagram in 1961. Tharp, Heezen, and Heinrich Berann (an Austrian painter and mapmaker) sketched the Indian Ocean map in 1967, published by National Geographic. They also made a map of the Antarctic Ocean floor in 1975. Next, Heezen and Tharp proceeded to draw the entire world’s ocean floor. Their previous work, new updates, several collaborations, and tireless efforts gave us the first map of the earth’s ocean floor in 1977.

The Queen Prevails

Managing to carve a place for herself in the male-dominated world, Marie Tharp was finally able to board a ship for research data collection in 1968. She and Heezen (after his death) were awarded the Hubbard Medal in 1978. It is the National Geographic Society’s highest honor. Tharp was a faculty member at Columbia University until 1983. In 1997, the Library of Congress named her one of the four greatest mapmakers of the 20th century. The Woods Hole Oceanographic Institution recognized her with the Mary Sears Woman Pioneer in Oceanography Award. She received the first annual Lamont-Doherty Heritage Award as a pioneer in oceanography in 2001. At the age of 86, she died of cancer in New York on 23rd August 2006. The International Astronomical Union, in 2015, named a crater on the moon as “Tharp” in her honor. Craters are depressions produced by the impact of volcanic activity, meteorite, or explosion.

In the words of Vicki Ferrini , a senior research scientist in marine geology and geophysics at Lamont-Doherty Earth Observatory, Columbia University, “Marie Tharp’s maps were building blocks for discoveries that transformed our understanding of the planet.” Even though her accomplishments were exceptional, Tharp’s work was often undervalued in a world dominated by men. For most of her career as a scientist, she worked in the background. In 1956, Heezen received credit for the rift valley discovery. Tharp’s name was also absent from major papers on plate tectonics for a long time. Nonetheless, she overcame the barriers that limited the progress of women during her time. She never looked for glory, loved her work above everything else, and used the opportunities coming her way whenever she could. Above all, she never gave up, contributing significantly to marine mapmaking and science. She is an incredible example of “girl-power,” not just for women of her generation, but for many other generations to come. Marie Tharp truly is the queen who rose to rule and showed us the backbone of our planet, unfolding the beautiful yet powerful story of the seas and oceans!
References
  1. Bettie Matheson Higgs. Understanding the Earth: the contribution of Marie Tharp. Geological Society, London, Special Publications, 506, 231-243, 12 October 2020.
  2. Earth Institute. Marie Tharp’s Adventures in Mapping the Seafloor, In Her Own Words. State of the Planet, Columbia Climate School. 24 July 2020.
  3. Cathy Barton. Marie Tharp, oceanographic cartographer, and her contributions to the revolution in the Earth sciences. Geological Society, London, Special Publications, 192, 215-228, 1 January 2002.

Apeksha Srivastava completed her MTech in Biological Engineering from the Indian Institute of Technology Gandhinagar, Gujarat, India. She is currently an aspiring science writer and a PhD candidate at this institute. Her research area lies at the intersection of science communication, and psychology. Aniruddha Mukherjee completed his BS-MS with a major in Biological Sciences from IISER Kolkata. He will be joining University of Alabama at Birmingham, U.S.A for his graduate studies in Biomedical Sciences in the coming fall. Apart from being a movie buff he enjoys cooking and playing chess.

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