Columbia University reports the death yesterday of Marie Tharp, an oceanographic cartographer who worked on the first world map of the ocean floor; she also co-discovered the Mid-Atlantic Ridge’s rift valley. She was 86.

A pioneer of modern oceanography, Tharp was the first to map the unseen topography of the ocean floor on a global scale. Her observations became crucial to the eventual acceptance of the theories of plate tectonics and continental drift in the earth sciences. Working with pens, ink and rulers, Tharp drew the underwater details, longitude degree by latitude degree, described by thousands of sonar readings taken by Columbia University researchers and others. Her maps have since become modern scientific and popular icons.

Also reprinted at Columbia News. Via Maps-L.

For more on Tharp, see the page dedicated to her at the Earth Institute at Columbia University’s web site, which includes some of her handiwork. Columbia University, where she was on the faculty from 1948 to 1983, has a page celebrating her life. See also news reports of her awards: the Women Pioneers in Oceanography Award in 1999; the first Lamont-Doherty Heritage Award in 2001. The Library of Congress’s Information Bulletin had an article about her in 2002. And she also has a Wikipedia entry.

Update, August 28: New York Times obituary (via Maps-L).

Update, Sept. 4: Los Angeles Times obituary.