Marie Tharp, an oceanographic cartographer who drew pioneering maps of the world's oceans and whose observations from the late 1950s through the 1970s helped scientists reconsider the geology of the seafloor, has died. She was 86.
Tharp died of cancer Aug. 23 at Nyack Hospital in Nyack, N.Y. The death was announced by Lamont-Doherty Earth Observatory of Columbia University, where she had worked from 1948 until retiring in 1982.
With longtime collaborator Bruce Heezen, Tharp published her best-known work -- the first global map of the bottom of Earth's oceans -- in 1977.
The groundbreaking map unmasked a dark world of deep canyons, impossibly broad plains and peaks higher than Mt. Everest. It was as if she had handed the public a snapshot of a previously unknown world.
"Their maps projected a new world into human minds, revolutionizing geology and our understanding of the planet we live on," New York Times science writer John Noble Wilford wrote in his 2000 book "Mapmakers."
He called it "one of the most remarkable achievements in modern cartography."
The maps weren't perfect, but they were "miles ahead of second place," said Robert Fisher, a research geologist at Scripps Institution of Oceanography in La Jolla and a contemporary of Tharp. "People around the world thought that if you drained the water, the seafloor would look like her maps."
Mapping the vast, hidden seafloor was "a once-in-the-history-of-the-world opportunity" for anyone, but especially for a woman in the 1940s, Tharp recalled decades later. She had been recruited to study geology at the University of Michigan only because so many men were in the military during World War II.
"You cannot overestimate the significance of her contributions. She wasn't just a mapmaker; there was a tremendous amount of insight and scientific intuition," said Mike Purdy, director of Lamont-Doherty Earth Observatory.
Because women weren't allowed to sail on research ships in the 1940s and '50s, Tharp remained behind, painstakingly plotting sonar readings of the ocean floor often sent back by Heezen, a marine geologist with whom she spent three decades in a personal and professional partnership.
Over five years, as she pieced together a puzzle of the North Atlantic Ocean, an enormous mountain range with a puzzling peculiarity took shape. What became known as the Mid-Atlantic Ridge showed signs of a crack down the middle that led Tharp to conclude that the seafloor was spreading, a radical notion at the time.
