How Marie Tharp’s Discovery of the Ocean Floor Led to Her Death by Cancer

Marie Tharp was a pioneering geologist and oceanographer who created the first scientific map of the Atlantic Ocean floor in the 1950s. Her work revealed the existence of the Mid-Atlantic Ridge, a massive underwater mountain range that runs along the center of the ocean basin. This discovery was crucial for the development of the theory of plate tectonics, which explains how the continents move and interact with each other over time.

However, Tharp’s groundbreaking research also exposed her to a deadly risk: radiation. In order to map the ocean floor, she had to use sonar data collected by ships that traveled across the Atlantic. These ships were equipped with devices that emitted sound waves into the water and recorded their echoes. The sound waves bounced off different features of the ocean floor, such as ridges, valleys, and volcanoes, creating a pattern of signals that Tharp could interpret and translate into a map.

The problem was that some of these devices used radioactive materials, such as radium and polonium, to generate the sound waves. These materials were highly dangerous and could cause cancer if handled improperly or inhaled. Tharp was not aware of this risk when she worked with the sonar data in her office at Columbia University’s Lamont Geological Observatory. She spent hours and hours analyzing thousands of strips of paper that contained the sonar signals, often holding them close to her face and breathing in their dust.

According to Columbia University, Tharp later developed cancer in her lungs and esophagus, which she attributed to her exposure to the radioactive sonar data. She underwent several surgeries and treatments, but the disease eventually took her life on August 23, 2006, at the age of 86.

Tharp’s Legacy and Recognition

Despite her tragic death, Tharp left behind a remarkable legacy of scientific achievements and contributions. She not only mapped the Atlantic Ocean floor, but also other oceans, such as the Pacific, Indian, and Arctic. She collaborated with her colleague and partner Bruce Heezen for over 30 years, producing stunning maps and globes that revealed the beauty and complexity of the underwater world.

Tharp’s work was initially met with skepticism and resistance from some male scientists, who dismissed her findings as “girl talk” or “moonshine”. They could not believe that the ocean floor was anything but flat and featureless, as they had assumed for centuries. However, Tharp persisted and proved them wrong with her meticulous analysis and elegant cartography. She eventually gained recognition and respect from her peers and the public, receiving numerous awards and honors for her work.

Some of these awards include:

  • The Penrose Medal from the Geological Society of America in 1997, which is considered the highest honor in geology.
  • The Patron’s Medal from the Royal Geographical Society in 2004, which is awarded for achievements in geography or exploration.
  • The Alexander Agassiz Medal from the National Academy of Sciences in 2005, which is given for original contributions in oceanography.
  • The naming of a crater on Venus after her in 2012, which is a tribute to her role in advancing planetary science.

Tharp’s maps and globes are now displayed in museums, libraries, universities, and government offices around the world. They are also used as educational tools for students and teachers who want to learn more about the ocean and its history. Tharp’s maps have been described as “one of the most remarkable achievements in modern cartography” and “works of art that also happen to make a colossal scientific point”.

Tharp’s life story has also inspired several books, documentaries, podcasts, and articles that celebrate her achievements and challenges. Some examples are:

  • Soundings: The Story of the Remarkable Woman Who Mapped the Ocean Floor by Hali Felt, which is a biography that explores Tharp’s personal and professional life.
  • Picture a Scientist by Sharon Shattuck and Ian Cheney, which is a documentary that features Tharp as one of three female scientists who faced discrimination and harassment in their fields.
  • Marie Tharp: The Woman Who Discovered The Backbone Of Earth by BBC World Service, which is a podcast episode that narrates Tharp’s discovery of the Mid-Atlantic Ridge.
  • How One Brilliant Woman Mapped The Ocean Floor’s Secrets by National Geographic, which is an article that summarizes Tharp’s career and legacy.

Tharp’s work has not only advanced our understanding of the ocean and its role in shaping our planet, but also inspired generations of women and girls who aspire to pursue careers in science, technology, engineering, and mathematics (STEM). She is widely regarded as a role model and a trailblazer for women in STEM, who often face barriers and biases in their fields. Tharp’s work shows that women can make significant contributions to science and society, despite the challenges and obstacles they may encounter.


Marie Tharp was a visionary geologist and oceanographer who created the first scientific map of the ocean floor. Her work revealed the existence of the Mid-Atlantic Ridge, which supported the theory of plate tectonics. However, her work also exposed her to radiation from the sonar data she used, which caused her to develop cancer and die in 2006. Tharp’s legacy lives on through her maps and globes, which are admired and studied by scientists and the public alike. She is also remembered as a pioneer and a hero for women in STEM, who continue to follow her footsteps and break new ground in their fields.

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