To understand the achievements of this pioneer, it's necessary to go back and describe the world as it was, and it was pretty surprising.
As late as the early 1960s, it was believed that the ocean floor was a flat, unchanging surface, as smooth as a sandy beach; that the edge of the continent sloped down to an abyssal plane, until the sea floor gradually sloped up at another continent. Scientists called the sea floor a "place of perfect repose." Belief in continental drift would cast you as a nut-job, though it had been suggested in 1922. There was very little understanding of earthquakes, no discovery of the Ring of Fire; no respect given to ideas of tectonic plates. The idea of a supercontinent of Pangaea (and the others that proceeded it) was scientific heresy. "There was still no definitive theory that explained how the earth's crust formed. Mountains, oceans, continents, islands, valleys -- even the earth's simplest features were still a source of contention."[i]
Not that they hadn't been trying: "In 1596 a Flemish geographer named Abraham Ortelius noticed that the projecting parts of Europe and Africa fit along with the recesses of America and looked as if they had been "torn away" from each other. And in 1838 a Scottish philosopher named Thomas Dick wrote that if western Africa snuggled up to the horn of Brazil one compact continent could be formed and may once have existed as such until they were "rent asunder by some tremendous power." In 1915 Wegener published the origin of continents and oceans in which he made an interdisciplinary argument that the Earth's surface was constructed from continental plates that moved laterally."[ii] When Wegener's work was translated into five languages in 1922, he was disparaged, and scientists complained that "if we are to believe his hypothesis we must forget everything which has been learned in the past 70 years and start all over again."
But technology was advancing: the first underwater photograph was taken in 1940. Sonar had been around for more than 30 years by that point, but its use wasn't standard; only some ships had it, and often the crews that had it didn't quite know how to use it…" Dr. Maurice "Doc" Ewing of Columbia University been collecting data about the ocean floor based on underwater acoustics[iii] since 1934.
Into this scientific vacuum stepped Marie Tharp of Ypsilanti, a graduate of the University of Michigan in geology who had been encouraged to take drafting which was a skill not usually necessary to become a geologist, but one [her professor told her] that would improve her chances of getting a job in a discipline dominated by men and old traditions."[iv]
She was meticulous, dedicated, open minded, scientific, hot-tempered, and stubborn. She was hired by Ewing as a geologist at a time when all the women in the field were either secretaries or assistants. Asked years later about Ewing's view of women in science, though, she replied that "I think he hated their guts."[v]
Her physiographic diagrams[vi], based on soundings of the ocean floor, however, were so valuable to the men of the department that she was overwhelmed with work. Ewing put a geologist named Bruce Heezen in charge of assigning her duties, a compliment because Bruce was Ewing's golden boy but also an insult because "he had just received his master's degree in geology, she had earned hers four years previously."[vii] But it began a life-long professional and personal relationship with Bruce.
Partnership with Bruce:
Bruce assigned her the task of finding the edges of the continents, but "no one had taken the time to do deep analysis of all the soundings… The marriage of artistry and science behind her analysis of this dry data…Marie's scientific knowledge, her eye for detail and her skill as an artist revealed not a vast empty plane, but an entire world of mountains and volcanoes, ridges and rifts, "She checked and rechecked her work, "looking closely at the ridge whose presence she confirmed, a wide bump where the ocean floor gained elevation. It was apparent on all six of the profiles [that she had done] which meant that it was a range not just one isolated mountain. And then something happened. "As I looked further at the detail and tried to unravel it," she said, "I noticed that in each profile there was a deep notch near the crest of the ridge." A deep notch, a rift… where new material came up from deep inside the earth, splitting the Mid ocean Ridge in two and pushing the sides apart. That, in turn, would move the continents on their various tectonic plates… This was something new. She kept studying it, checking the sounding records over and over again to make sure she hadn't mis-plotted a depth. When she was certain she was right, she called for Bruce [and] their first big fight followed. Bruce laughed dismissively, then shouted about women's intuition... Marie shouted about Bruce's boring old mind; at least she says, she uses hers for something, and anyway, what is he afraid of? She knows exactly what he's afraid of. They both know that the existence of such a rift means continental drift. Wegener's theory [from 1922] is so reviled in the United states that it's very well known. Bruce paces around the room, puts his hands on his hips, accuses her of daydreaming. Marie is just about had it; she's exercising extreme willpower to stop herself from hurling a stapler at him. She threatens to quit. Her officemates have evacuated. Girl talk, Bruce finally bellows, referring to the rift. It cannot be. It looks too much like…" "…continental drift, Marie says. Continental drift, Bruce says. They look at each other. How do you explain something like that…. Bruce told her to do the whole job over again. And she did.
Eight months after Marie began work on those first six profiles [of oceans] [in 1952] she could sketch one nearly continuous rift valley all across the world that was two miles deep, 20 miles wide, and 40,000 miles long, quite possibly the largest geologic feature on earth.[viii]
The first scientific paper on it came out in 1956, authored by Ewing and Bruce. Marie's name was absent.
The scientific community called it "a pack of lies." Even Jacques Cousteau who "had tacked it to a wall in the mess hall of his famed ship, the Calypso, decided he'd prove Marie and Bruce wrong by crossing the Atlantic, filming the ocean floor with the photo sled apparatus he had designed. Instead of proving them wrong, he proved them right.
Gender
"Marie's work (both in the office and in public presentations) was profoundly affected by her gender. Her gender prevented her from going out on [ocean-going] expeditions, which in turn forced her to collect information about the ocean floor in unconventional ways: studying the relief of Iceland and India, forming a partnership with a man who could go out on ships and was an ace at exchanging data with other scientists. Her gender was the reason she had been cast as research assistant when she first appeared at [Columbia]; it was why Ewing had turned her over to Bruce back in 1952 when she tried to quit her job; It was why all of the work she'd subsequently done had to carry his name and why, of the two of them, Bruce was always the one asked to deliver presentations of their work."[ix]
It's also why, after Bruce's untimely death in his 50s, "others took all of her projects from her, leaving just a very small mapping project for her. Then a committee member came to her house and took the in-progress maps, data, and contours for the sheets whose coordination had been transferred to other scientists --"it was forcibly stolen," was how Marie put it, decades later."
Success
Despite the obstacles, though, her work profoundly changed the way we see the planet, thanks in large part to a panoramic and painted depiction of Marie's diagram that "made its way into 6 million homes" via the National Geographic magazine in 1967. "The public's understanding of the earth made a giant leap forward. What had been shocking was made popular."[x] And "we can't underestimate the role her maps played in helping people visualize the features of plate tectonics. That revolution could not have happened without a lot of people being able to see the features she drew."[xi]
One ocean
While National Geographic played an enormous part in the dissemination of their work, Marie and Bruce were ultimately too radical in their thinking for the magazine. By 1975, she and Bruce had come to believe [unlike the NatGeo Society that recognized 5 discrete oceans] that the world's oceans were all part of one interconnected system.[xii]
Honors
There were plenty of ups and downs in her professional and personal life that are outlined in the biography, but I have two favorite stories of honors given to her: In 1997, the Library of Congress held a celebration of their 100th anniversary with an exhibit called "American Treasures from the Library of Congress." [The opening night gala] was attended by President Bill Clinton. Marie was old and in a wheelchair at that point and taken past the exhibit's treasures: the original rough draft of the Declaration of Independence, the contents of Abraham Lincoln's pockets the night he was assassinated, maps drawn by George Washington when he was a surveyor, the first motion picture, the Emancipation Proclamation, pages from Lewis and Clark's journals… and one of her maps of the ocean floor… Marie started to cry when she saw it."[xiii]
The second was in 2009 with the release of Google Ocean, containing a layer called the "Marie Tharp Historical Map," which, when turned on, wraps her World's Ocean Floor Panorama around the earth… [Her New York Times obituary called] it one of the most remarkable achievements in cartography."[xiv]
Even Today
And yet there's more work to be done while in 1956 we had studied a fraction of 1% of the ocean floor, "even today, only about 5% of the ocean floor has been studied in any detail,"[xv] with only 10% of it surveyed using multibeam sonar which means that scientists have mapped Venus, the earth's moon, and Mars in more detail (with several thousand, 1000, and 250 times more detail, respectively) than earth."[xvi]
[i] chapter 4
[ii] Chapter 4
[iii] Chapter 7
[iv] chapter 4
[v] chapter 31
[vi] Physiographic diagram[s] [are] sketches of the topographical features of an area, not just simple strokes showing outlines of mountains and hills, but intricate nests of black lines that made the crags and ridges of the ocean floor look three-dimensional… The method had been created by a Columbia professor of geomorphology… who had been sent to Versailles after World War One to help world leaders redraw European boundaries. When he got there and observed those powerful men staring blankly at topographical maps, "unable to tell a mountain from a molehill or a river from a valley or anything from a shoreline," [the inventor named Lobeck] developed the physiographic diagram." Chapter 11
[vii] Chapter 9
[viii] Chapter 11
[ix] chapter 17
[x] Chapter 18
[xi] chapter 33
[xii] Chapter 24
[xiii] Chapter 31
[xiv] Chapter 33
[xv] chapter 12
[xvi] chapter 33