GeoCarta Has Moved

Dec 30, 2006

Mapping Continental Drift

In the middle of the last century, two cartographers working at Columbia University made discoveries that rewrote geophysics. Sunday's New York Times Magazine tells the story of Marie Tharp and Bruce Heezen.

In 1948, Ms. Tharp was hired by the geology department at Columbia University where she met Bruce Heezen, a graduate student from Iowa. Mr. Heezen gave Ms. Tharp a stack of soundings of the floor of the Atlantic Ocean and told her, “Here, do something with these.”

Ms. Tharp and an assistant methodically plotted the measurements by hand on huge sheets of paper. As the map of the ocean floor took shape, Ms. Tharp noticed something fascinating. In plotting an under sea mountain range, known as the Mid-Atlantic Ridge, there appeared valley running right down the middle of it. This “rift valley” was a huge discovery. The valley marked a seam in the crust of the planet, At the seam, huge continent-size plates rose from the interior of the earth to the surface in what geologists refer to as “drift,” and moved outward in both directions.

The discovery of this rift valley was very unpopular among geophysicists of the day, who contended that the Earth's surface was static. Mr. Heezen himself remained unconvinced for some time, dismissing it as, “Girl talk.”

But Ms. Tharp persevered, making a believer out of Mr. Heezen. Over the span of twenty years, Mr. Heezen and Ms. Tharp would map the floors of all of the world’s oceans, discovering rift valleys in every one and convincing the scientific community of the reality of continental drift.

Bruce Heezen died in 1977 on a research vessel off the coast of Iceland. Marie Tharp passed away earlier this year.