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Continental drift
Continental drift was a theory that explained how continents shift position on Earth's surface. Set forth in 1912 by Alfred Wegener, a geophysicist, and meteorologist, continental drift also explained why look-alike animal and plant fossils, and similar rock formations, are found on different continents -
Weneger published "The origin of continents and oceans"
Though most of Wegener's observations about fossils and rocks were correct, he was outlandishly wrong on a couple of key points. For instance, Wegener thought the continents might have plowed through the ocean crust like icebreakers smashing through the ice. -
Wegener's death
Despite his incredible evidence for continental drift, Wegener never lived to see his theory gain wider acceptance. He died in 1930 at age 50 just two days after his birthday while on a scientific expedition in Greenland. -
Tharp sought a geology job at Columbia University
Women couldn’t go on research ships, but Tharp could draft, and was hired to assist male graduate students.
Tharp worked with Bruce Heezen, a grad student who gave her seafloor profiles to draft. These are long paper rolls that show the depth of the seafloor along a linear path, measured from a ship using sonar. -
Tharp's incredible discovery
One of her important innovations was creating sketches depicting what the seafloor would look like. These views made it easier to visualize the ocean floor’s topography and create a physiographic map.
Tharp’s careful work revealed something no one had ever described before: a cleft in the center of the ocean, miles wide and hundreds of feet deep. Tharp suggested that it was a rift valley–a type of long trough that was known to exist on land. -
First Physiographic map of the mid-atlantic ridge
First physiographic map showing the physical features of the Atlantic ocean floor, published by two geologist; Bruce Heezen and Marie Tharp -
Heezen Talks at Princeton University about the "rift valley epicenters"
When Heezen, as a newly-minted Ph.D., gave a talk at Princeton in 1957 and showed the rift valley and epicenters, geology department chair Harry Hess replied, “You have shaken the foundations of geology.” -
Geological Society of America published “The Floors of the Oceans: I. The North Atlantic”
by Heezen, Tharp, and “Doc” Ewing, director of the Lamont Observatory, where they worked. It contained Tharp’s ocean profiles, ideas and access to Tharp’s physiographic maps. Some scientists thought the work was brilliant, but most didn’t believe it. French undersea explorer Jacques Cousteau was determined to prove Tharp wrong. He even sailed to the Mid-Atlantic Ridge, To Cousteau’s surprise, the film showed that a rift valley existed. -
Harry Hess proposed the seafloor was like a giant conveyor belt.
New seafloor formed on either side of the ridges as magma flowed out and pushed away from the old seafloor, and when finally reached the distant trenches, the old ocean crust was cooled and dragged down into the mantle and recycled. -
Indian Ocean map, published by National Geographic
Hess and Tharp's collaborations. -
World Ocean Floor map
Hess and Tharp's collaboration is now held at the Library of Congress. -
Heezen Death
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Heezen (posthumously) and Tharp were awarded the Hubbard Medal
the National Geographic Society’s highest honor, joining the ranks of explorers and discoverers such as Ernest Shackleton, Louis and Mary Leakey, and Jane Goodall. -
Marie Tharp death
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