*http://www.columbia.edu/cu/news/06/08/tharp.html*
**

*Remembered: Marie Tharp, Pioneering Mapmaker of the Ocean Floor*

Marie Tharp
/Marie Tharp /

Marie Tharp, a pathbreaking oceanographic cartographer at the
Lamont-Doherty Earth Observatory, co-creator of the first global map of
the ocean floor and co-discoverer of the central rift valley that runs
through the Mid-Atlantic Ridge died Wednesday August 23 in Nyack
Hospital. 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.

"I had a blank canvas to fill with extraordinary possibilities, a
fascinating jigsaw puzzle to piece together," Tharp said in an oral
history interview conducted for the 50th anniversary of Lamont-Doherty
in 1999. "It was a once-in-a-lifetime — a
once-in-the-history-of-the-world — opportunity for anyone, but
especially for a woman in the 1940s."

Marie Tharp at work
/"I was so busy making maps I let them argue," Tharp once said of the
debates that swirled around her drafting table./

Piecing together maps that they made, she and colleague Bruce Heezen
revealed a 40,000-mile underwater ridge girdling the globe. With the
discovery, they laid the foundation for later work that showed the sea
floor spreads from central ridges and that the continents are in motion
with respect to one another — a revolutionary and controversial theory
among geologists at the time.

"I was so busy making maps I let them argue," Tharp once said of the
debates that swirled around her drafting table. "I figured I'd show them
a picture of where the rift valley was and where it pulled apart.
There's truth to the old cliché that a picture is worth a thousand words
and that seeing is believing."

Tharp was born in 1920 in Ypsilanti, Michigan. As the daughter of a soil
surveyor for the U.S. Department of Agriculture, she was constantly on
the move — to the south in the winter months and north in the summer. By
her own reckoning, she attended nearly two dozen schools by the time she
graduated from high school. More importantly, she had also begun to get
a feel for landscapes and mapmaking.

"I was so busy making maps I let them argue," Tharp once said of the
debates that swirled around her drafting table.

Tharp attended Ohio University, changing her focus several times until
she graduated with majors in English and music and four minors. She
later obtained a masters degree in geology from the University of
Michigan and in math from the University of Tulsa. Yet, as Tharp said,
she was "still searching for something more challenging," and moved
east, where she eventually joined the staff of the geology department at
Columbia University in 1948 as a research assistant to Maurice "Doc" Ewing.

For the next several years, she sat at a desk plotting soundings of the
ocean floor. When Tharp started piecing together the profiles, she
noticed that it was not the line of mountains that formed the most
continuous feature through the middle of the North Atlantic, but a cleft
running down the center with peaks on each side. She thought it might be
a rift valley like the one found in East Africa, an idea that would
support the budding hypothesis that the continents move across the
surface of the Earth. Heezen, who was then a graduate student, dismissed
the idea as improbable to the point of being scientific heresy.

But the improbable soon proved probable. Other data showed large numbers
of earthquakes occurring along the rift, confirming Tharp's hunch. Based
in part on the incontrovertible pictures she provided, the concept of
plate tectonics moved into the realm of legitimate debate and later into
the mainstream of earth science.

Map of the Ocean Floor
<http://www.columbia.edu/cu/news/06/08/images/HeezenTharp_900.jpg>
In 1959, Marie Tharp and colleague Bruce Heezen completed their first
map of the North Atlantic. "The significance of Tharp's achievement and
the importance of the maps cannot be overstated," said Mike Purdy,
director of Lamont-Doherty.

See a larger version of the ocean floor map
<http://www.columbia.edu/cu/news/06/08/images/HeezenTharp_900.jpg>

In 1959, Tharp and Heezen completed their first map of the North
Atlantic. In 1961, they completed the South Atlantic and in 1964, the
Indian Ocean. After Heezen died in 1973, Tharp focused her energy on
completing a comprehensive view of the world's oceans. The World Ocean
Floor map was published in 1977 by the Office of Naval Research and is
still in wide use today.

"Marie was the grand dame of ocean exploration," said Bill Ryan, Doherty
Senior Scholar at Lamont-Doherty and a long-time colleague of Tharp's.
"It is a very sad day, but we can also rejoice in how she so splendidly
unveiled the hidden abyss. She didn't just make maps; she understood how
the Earth works."

Only in recent years has Tharp begun to be recognized for the breadth
and significance of her contributions to science. In 1998 she was
honored during the 100th anniversary of the Library of Congress'
Geography and Map Division. The following year, she was recognized by
the Woods Hole Oceanographic Institution. In 2001 she was honored by her
home institution with the Lamont-Doherty Heritage Award. Today, a
fellowship at Lamont-Doherty to promote women in science through the
ADVANCE program bears her name.

"The significance of Tharp's achievement and the importance of the maps
cannot be overstated," said Mike Purdy, director of Lamont-Doherty. "She
was a pioneer in her science, playing a crucial role in the early days
of sea-floor spreading research, and she was a pioneer in her
profession, succeeding as a woman in a field dominated for decades by
men. But most of all she was a wonderful person, a great colleague and a
happy friend to so many of us."

Tharp has no family, but is survived by her devoted staff. A celebration
of her life and achievements will be held on Sunday September 17 at 2:00
p.m. at the Tappan Reform Church in Tappan, N.Y. In lieu of flowers,
Tharp requested that donations be made to the Marie Tharp Fund at
Lamont-Doherty. Plans for a symposium honoring her many contributions to
the scientific community will be announced at a later date.

This article originally appeared on the Earth Institute at Columbia
University <http://www.earth.columbia.edu> web site.