Often history books are printed, cover to cover, with the names of successful men. Their accomplishments and discoveries are proudly listed and never questioned. There are, however, often overlooked heroes for their time, who may have contributed or made groundbreaking discoveries of their own. One of those underappreciated legends of their time is geologist and ocean cartographer, Marie Tharp. Born and raised in Ypsilanti, MI in 1920, Marie was the daughter of a school teacher and a soil surveyor for the United States Department of Agriculture. Because her father worked for the government, the Tharp family frequently traveled around the U.S. (Barton, 2002). The Tharps settled on a farm in Ohio in 1936, where Marie decided to continue her education. Marie began school at Ohio University in 1939, where she obtained an English degree in 1943 (Barton, 2002). Marie entered the world of higher education in the midst of World War II, a time where men were sent to war, leaving vacancies in local jobs that were deemed as “men’s work” (The Ages of Exploration, 2017). Because the petroleum industry was suffering with all of the male leaders at war, women were increasingly recruited. Acknowledging the exceptional grade she received in a geology class at Ohio University, the University of Michigan petroleum geology program reached out to Marie (Barton, 2002). Marie went on to become a “Petroleum Geology Girl” and graduated from the program in 1944 (Bressan, 2013). After Marie received her second degree, she went on to work as a research assistant at the Lamont Geological Laboratory at Columbia University in New York, where she met Bruce Heezen (The Ages of Exploration, 2017). Prior to 1950, little was known about the ocean floor. Most people assumed it was a flat underwater plain of mud (The Ages of Exploration, 2017). Marie and Bruce were tasked with the seemingly impossible task of figuring out what exactly was down there. The process of mapping the ocean floor was incredibly cumbersome, but the duo was certainly committed to the project. In order to begin a task that would span a few decades, there was an immense amount of data to be collected. It should be noted that women were not allowed on boats at the time, so Heezen ventured out on research vessels and collected the initial data. Much of the data came from sonar measurements of ocean depths, which were sent back to Marie. Tharp dissected the sonar readings and drew the details of the ocean floor, each longitude degree by latitude degree, using only a pen and ruler (The Age of Exploration, 2017). The technique that Tharp and Heezen used is the called physiographic mapping, which relates topographic features to underlying geology. The diagrams produced by Marie mostly utilized light and texture, rather than color, and were sketched by hand (Barton, 2002). In an interview, Tharp said she was never overwhelmed by the amount of data they had, but rather by what they lacked. “We’d use everything available, but there would be blank areas,” she said. “I’d work up a blank area with what we could get. The biggest challenge was just to keep providing data for the blank areas and to upgrade the areas that we changed our minds on” (Lawrence, 1999). Tharp and Heezen essentially discovered that the ocean floor was not flat, but covered with various kinds of geological features like canyons, ridges, and mountains, just like on the Earth’s above-ground continents. Oftentimes, these oceanic geological features were much larger and deeper than anything seen on the planet’s surface (Maxwell, 2017). In the process of plotting the data, Marie made a substantial discovery that helped to spark one of the greatest scientific revolutions in history. While working on the project, Tharp’s maps revealed 40,000 miles of an underwater ridge that runs along the globe. In 1953, her observations led her to promote the controversial theory of continental drift and seafloor spreading (The Age of Exploration, 2017). German meteorologist Alfred Wegener was the first to promote the theory, stating that “continents once fit together like pieces of a giant jigsaw puzzle, to make one vast supercontinent” (Marshak, 2012). Following the discovery of the ridge, Tharp also integrated research data from other sources, such as the Woods Hole Oceanographic Institution and data from seismographs of underwater earthquakes. Tharp noticed that several of the small earthquakes occurring under the sea came from her proposed rift valley, which is one more supporting piece of supporting evidence of Wegener’s theory (Maxwell, 2017).With diligent work, Marie and Bruce completed their first map of the North Atlantic ocean in 1959. The popularity of the North Atlantic map led Tharp and Heezen to produce a map of the South Atlantic in 1961. Seeing the almost perfect conformity in shape among the the ridge and the South American and African coastlines, inspired a number of scientists to tackle the continental drift question (Lawrence, 1999). Marie and Bruce went on to create maps, using the same methods, of the South Atlantic and Indian Ocean in the early 1960s. In 1977, the team published a comprehensive map of the entire ocean, called the World Ocean Floor Map. In that same year, Bruce Heezen died (Maxwell, 2017). As a woman scientist in the mid 20th century, Marie Tharp’s work was not always credited, however, today, Marie is recognized as a pioneer in a field dominated by men. Until Bruce Heezen’s death, Marie had worked in his shadow, and was rarely credited as author or co-author of research publications (Lawrence, 1999). In 1997, the Library of Congress named her one of four individuals “who have made major contributions to the field of cartography.” In March 1999 the Women’s Committee of the Woods Hole Oceanographic Institution honored her with its Women Pioneers in Oceanography Award. In the same interview, Tharp explained she didn’t mind the belated honors. She was never after the glory. “I have absolutely no resentments,” she said. “I thought I was lucky to have a job that was so interesting. I just had the fun of putting the puzzle together. I had the whole world to figure out” (Lawrence, 1999). Marie died at the age of 83 in 2006. A few years later, in 2009, Google continued the trend of honoring Marie, and added the Marie Tharp Historical Map as a layer over the oceans on Google Earth (Jha, 2009). Looking back at Marie’s life and accomplishments, it’s truly impressive. Mapping the world’s oceans is by no means a small task. It is a shame that Marie didn’t receive as much credit as she should have in her life, however, the fame belongs to her now.