The Universe Within (17 page)

But Tharp’s data did not go away; in fact, the more she plotted, the more her rift became obvious. Heezen’s resistance withered with the mountain of new data that emerged over the ensuing months. He not only became sold on Tharp’s idea, but he came up with the even more ambitious plan to make a map of the entire
ocean floor.

Around this time, American Telephone and Telegraph realized it had a problem with transatlantic cables that were breaking frequently. The company contracted with Ewing’s lab to check the situation. Plotting the seismic data Ewing’s team collected at a fine scale, Heezen, Tharp, and the team found a stunning pattern. The
earthquakes ran in a regular line in the ocean. And not just anywhere in the ocean; they did so in the middle of Tharp’s rift valleys. People started to become very interested in Tharp’s rifts.

“Girl talk” became the subject of a professional seminar Heezen gave to the assembled experts in the geology department
of Princeton University in 1957. In the crowd was
Harry Hess, now chairman of the department. After seeing Heezen’s presentation of Tharp’s rifts and their earthquakes inside, Hess rose to say, “Young man, you have shaken the foundations of geology.”

Hess was primed to love Heezen’s talk because of his work during
World War II mapping submarine mountains: they revealed a pattern similar to those of Tharp’s ridges. His mountains were high near the big ridges and became eroded the farther away he looked. To Hess, this meant that the mountains closer to the ridges were relatively young; those farther from the ridges, old. Along with the data revealing active splitting at the ridges, the only explanation could be that new seafloor was created at the ridge and the seafloor was indeed spreading.

Geological work at this time was an international effort filled with story after story of discovery and persistence. One six-foot-five-inch Dutchman lay curled up in a tiny submarine for weeks on end while mapping
deep-sea trenches. British, Canadian, French, Dutch, and Japanese scientists spent months on board ships mapping coasts, oceanic ridges, and trenches. All of this activity brought the need for a new view of Earth. With data pouring in from around the globe, the deep-sea trenches started to reveal a pattern: they too were the sites of frequent earthquakes and, on many occasions,
volcanic magma emerging at the surface.

Heezen’s presentation stimulated Hess to devise a theory to explain the different observations. If new seafloor is created at the ridges, then it had to be
recycled somewhere else, lest Earth be ever expanding. To Hess, the pattern of earthquakes and other physical features of the deep trenches fit the bill. He proposed the notion that seafloor emerges at the ridges, spreads as it moves away, and later sinks and is destroyed at the trenches. The seafloor is now seen to be a huge
conveyor belt.

Hess wrote up this idea in a manuscript that he circulated among colleagues but hesitated to publish for two years. He called
his idea “an exercise in
geopoetry,” as much to defer criticism that it was speculative as to celebrate its beauty. In fact, elements of Hess’s idea, like many ideas in science, had been proposed by somebody else before.
Arthur Holmes, a brilliant British geologist, derived a similar recycling idea from pure theory in 1929. Holmes, one of the pioneers in the development of modern methods of
dating rocks, found his inspiration in
Wegener himself.

Lacking for geopoetry were insights into the age of the seafloor; eroded mountains and rifts alone weren’t going to put an end to almost a century of skepticism. Hess presented his theory at Cambridge in the early 1960s, and in the audience was a young student by the name of
Frederick Vine. Excited by Hess’s theory, Vine and his adviser,
Drummond Matthews, hunted for an indicator of the age of the rocks at the bottom of the ocean so that they could compare the age of the seafloor on either side
of Tharp’s rifts. The two developed a clever technique using the data they had at hand. If the seafloor was spreading like a
conveyor belt, then the youngest seafloor should be close to the ridges, and the ages should increase as you move away. Furthermore, the ocean floor should be the same age at the same distance on either side of the ridge. Vine and Matthews used the pattern of
magnetism inside the rocks of the seafloor as a marker for their ages. They found exactly what was predicted: young floor is close to the ridge, older floor farther away, and the ages on either side of the ridge match. The seafloor was spreading, just as
Hess and
Holmes before him had proposed.

At the same time Vine and Matthews were preparing their publication,
Lawrence Morley of the Canadian Geological Survey was assembling his own data. He submitted his analysis to the august journal
Nature
. It was rejected. He then submitted it to the more specialized
Journal of Geophysical Research
in 1963. Several months passed. Then it was returned with an anonymous note from one of the referees saying, “Found your note with Morley’s paper on my return from the field. His idea is an interesting one—I suppose—but it seems most appropriate over martinis, say, than in the
Journal of Geophysical Research
.” This delay cost Morley dearly; soon after he got news of his rejection, Vine and Matthews’s paper appeared.

Vine and Matthews did not measure the age of the seafloor directly; the technique they used was so new that it required refinement before Hess’s
geopoetry was to become universally accepted. Confirmation came only a few years later with more surveys of the ocean floor led by
Columbia, Stanford, and the Scripps Research Institute in La Jolla, California. With the mountains of data, new ideas, and
Wegener’s classic insights,
Time
magazine produced an article in 1970 with a title that says it all: “Geopoetry Becomes Geofact.”

For professors like Hess and
Heezen, this revolution in thinking
led to fame and academic eminence. But old feuds die hard. Because of spats with
Ewing, largely due to their support of continental drift, Heezen and
Tharp had become persona non grata at Columbia. Heezen, a tenured professor, could not be fired, but even so Ewing found ways to demean him: he stripped Heezen of his departmental responsibilities, cored the locks from his office door, dumped his belongings in the hall, and gave his office away. Ewing did manage to fire Tharp. Lacking an office, she ended her career working out of her Nyack, New York, home. Her view of the tumultuous personal and scientific times was revealed twenty years after Heezen’s death when, during an oral history project at Columbia, she recalled, “I worked in the background for most of my career as a scientist, but I have absolutely no resentments. I thought I was lucky to have a job that was so interesting. Establishing the rift valley and the mid-ocean ridge that went all the way around the world for 40,000 miles—that was something important. You could only do that once. You can’t find anything bigger than that, at least on this planet.”

If
Wegener’s continental drift evokes gradual movement and
Hess’s
geopoetry a sublime relationship between parts of Earth, then the word that describes the merger of the two, “
tectonics,” conjures an idea that rattles our world to its foundations. The 1960s had revolution in the air in music and politics, but arguably the most lasting change was the emergence of a new way of seeing the planet. Patterns of rocks and fossils that were once bizarre started to make total sense. Scientists were gleefully revising centuries of scientific dogma, and foremost among these revolutionaries was
John Tuzo Wilson, a Canadian geologist. Wilson, a physicist by training, had a personal quality that was to serve him well during this time. Late in his career
he summed it up: “I enjoy, and have always enjoyed, disturbing scientists.”

In the late nineteenth century,
paleontologists recognized that North America and
Europe both have distinctive
mountain ranges that run north to south. The
Appalachian Mountains extend from Maine to North Carolina in the United States, and the
Caledonians course from Morocco to
Scotland in
Africa and Europe. One place in northern Scotland has Appalachian
fossils inside its rocks. And in a few places Appalachian rocks have European fossils inside. How did the creatures get there? One could invoke swimming, except that most of these shelly animals live fixed to the seabed and do not travel far.

To Wilson, armed with the new theory, the answer to this puzzle was akin to what happens when a child plays with a peanut butter and jelly sandwich. What happens when the child takes
the two separate halves of the sandwich, puts them together, and then opens them up again? The mushed jelly and peanut butter reflect what happened when the sandwich closed up. The bits of peanut butter left on the jelly side and jelly on the peanut butter side reflect the opening.

To Wilson, Europe, North America, and the Atlantic
Ocean behaved the same way as that sandwich. He proposed that there was an ocean that separated the
continents hundreds of millions of years ago. This ocean closed, and as the continents from either side rammed into each other, a chain of mountains formed. When the continent reopened, the chain broke into two pieces, leaving what are today the Appalachians and the Caledonians. And those odd American fossils in Europe? They were just patches of the old continent that got left behind when the Atlantic Ocean opened.

Wilson, and the many scientists who followed, found the globe that we learn in school is only a snapshot in time: there have been innumerable globes in our past, and there will be many more in the future. Earth’s crust is composed of a number of plates, each containing ocean, continent, or both. These plates move relative to one another as the convection under the crust causes the
seafloor to
spread at
Tharp’s
ridges and to ultimately be destroyed at the
deep ocean
trenches.

In 1984, over half a century after
Wegener’s death,
NASA released the first direct measurements of continental
drift. About twenty stations around the world were established, each capable of bouncing lasers off
satellites equipped with reflectors. A
telescope next to the laser on the ground picked up the reflection by the satellite. By measuring the time that laser light took for the round-trip to each station, NASA calculated the distance to the satellite. If the plates move, then the distance to the satellite should change over time. Using this technique, NASA showed that North America and Europe are getting farther apart by 1.5 centimeters per year. Australia is heading for Hawaii at about
7 centimeters per year. The plates on our planet move about as fast as hair grows on our scalps.