The results from the Pacific exactly coincided with what Tharp and Heezen in the Atlantic would soon so boldly imagine: that in all the oceans, new seafloor was being created by the endless volcanic gurgitations along the mid-ocean ridges and then, as still newer material followed it, was spreading itself away from the central rift valleys.
The world’s newest material was being born in such places: the ridges were the locus of the origins of today’s continental geography. Western Africa stands where it does, and is shaped as it is, because of all the eruptions and movements in an invisible underwater suture line lying a thousand miles off its coastal horizon. The same is true for almost every other coastline in the world. The ridges made them all.
The ridges were also central to the construction, also in the mid-1960s, of the ideas that gave rise to the now familiar theory of plate tectonics. The theory had been built directly onto this now confirmed and fully believed idea of continental drift. It is a theory of such logic, elegance, and beauty that we sometimes imagine it has been with us for eons past; it is in fact not much more than half a century old.
The unique tectonic architecture of the Pacific Ocean, with its major and minor plates jostling and shifting around its edges, has created an immense coastal zone displaying the most intense volcanic and seismic activity, the so-called Ring of Fire.* [U.S. Geological Survey (USGS).]
Current thinking holds that the world’s outer solid crust is composed not of one continuous surface, as on an orange or a baseball, but of a number of enormous plates, each of which floats on top of the hot and relatively mobile upper mantle of the planet. There are seven major plates, eight lesser plates, and a host of other, new ones being discovered all the time. No fewer than sixty-three had been named at the time of writing.
The Pacific Plate is by far the biggest. It occupies 103 million square kilometers, thirty times the area of the continental United States. It is roughly the same shape as the island of Ireland. It has a long and quite smooth, convexly curved eastern boundary that runs southward across from the Gulf of Alaska down to the Southern Ocean.
The western side of the plate has a different appearance: a serrated and indented boundary that runs down from the Kamchatka Peninsula, past Japan and then New Guinea, turning back toward the center of the ocean, and then shifting sharply down southward, to where it casually bisects New Zealand—with the country’s North Island on the outside of the plate, half of the South Island within it, and the long chain of the Southern Alps marking the dividing line between the Pacific Plate and its western neighbor, the Indo-Australian Plate. The Pacific Plate underlies much of the ocean, but not all of it.
Crucially, all the plates move. They move when magma below them swirl, and they move in concert with the swirling going on beneath them. So if the magma is moving in a northwesterly direction, the plate that lies atop it moves in that direction, too. Most plates move relatively slowly—the North American Plate, for example, is shifting westward at about twenty millimeters a year, somewhat less than the rate at which human fingernails grow. The Pacific Plate is, by contrast, something of a speed demon: it moves ten times as rapidly, and in a habitual northwesterly direction, covering something like two centimeters each year.
The evidence for this is plain to see. A glance at any physical map of the Pacific Ocean shows that almost all the myriad island groups on its western side are strung out in roughly elongated lines, all stretched in a generally southeast–northwest direction. This is because the plate on which they sit is moving beneath them from the southeast to the northwest, persuading them to align themselves just as boulders and debris are aligned on the surface of an ever-moving glacier. By contrast, the islands that lie beyond the plate’s known borders are arranged higgledy-piggledy, with no evident pattern to their location on the planetary surface.
All that is seismically spectacular about the Pacific Ocean—and there is plenty, with earthquakes and volcanoes and tsunamis happening with what, to humans, is dismaying frequency—happens along the edges of its underlying plate, where it abuts its neighboring plates. Most famously, there is the so-called Ring of Fire, which runs for twenty-five thousand miles around the ocean’s northern, eastern, and western edges. This ring—or, more suitably (since it is discontinuous, and isn’t truly a ring), this belt—plays host to more than four hundred volcanoes. Mount St. Helens, Mount Pinatubo, Krakatoa, Taupo, Popocatepetl, Unzen—the majority of the planet’s earthquakes occur on these same three edges of the Pacific, including the three biggest ever recorded in history, which occurred in Chile in 1960, in Alaska in 1964, and in Japan in 2011.
Yet, for all their savage spectacle, these earthquakes are not necessarily important in strictly scientific terms. It turns out that the most geophysically significant discovery of recent times was not made among the giant volcanoes or violent earth shakings of the Ring of Fire. Rather, it was made above the East Pacific Rise, which appears relatively peaceful, unspectacular, and quite lacking in the power and dangerous majesty so visible elsewhere.
For the Rise is actually where the very makings of the modern Pacific Ocean occur, the one place in the Pacific where ocean floor spreading is provably and visibly happening. This is where the present-day Pacific Ocean is being manufactured, and has been manufactured since the plate made its first appearance about one hundred eighty million years ago. Elsewhere, at all those places around the plate edges where there are volcanoes or earthquakes, the plate is either subducting beneath a neighboring plate (in Japan, the Kuril Islands, the Aleutians, and the Cascade Range in the Pacific Northwest), or else sideswiping its neighbor (most infamously along the San Andreas Fault, where it sideswipes the North America Plate, and triggers historically important earthquakes).
The East Pacific Rise is a classic mid-ocean ridge, a range of undersea mountains marking the boundary between the Pacific Plate and its three southeastern neighboring plates: the tiny Cocos Plate, the enormous Antarctic Plate, and between them, most critically, the Nazca Plate, which lies off South America’s west coast and runs from Colombia to halfway down Patagonian Chile. This is the most energetic of the ridge’s spreading zones. The Pacific Plate and the Nazca Plate are moving apart very fast: the crust above them moves about 7.5 centimeters a year on each side, or 15 centimeters of total spreading annually, much faster than around any other mid-oceanic ridge.
Bruce Heezen died in 1973, after which Marie Tharp took her ship alone and onward into the vastness of the Indian Ocean and then farther on east, to the Pacific. With the research from that trip, she completed in 1977 the first-ever map2 of the world’s entire undersea mid-ocean ridge system. And once the ridges were fully mapped, and had been accepted as the places where new material was gushing out of the earth’s mantle to form the greatest features of our planet, armies of geophysicists descended on them, to determine exactly what was happening there.
The Alvin would give them the ability to do precisely this. So, in early 1977, the heroic and salt-stained little craft, shackled onto the deck of her mother ship, the Lulu, journeyed for the first time in her career through the Panama Canal, bound for her assignation with oceanographic history.
Another Woods Hole vessel, the Knorr, had preceded her, heading down to a spot in the ocean where curious temperature anomalies had been detected, hints of something odd, something worth divining. It was suspected that something, quite possibly hot water, was pouring out the top of the ridge, much as geyser water would gush out of solid earth at volcanically manic places such as Yellowstone and Rotorua. The site in the ocean was some four hundred miles west of the Ecuadorian coast, two hundred fifty miles northeast of the Galápagos chain, on a ridge that spun out from the eastern flank of the East Pacific Rise.
It was here that the discoveries would be made by Alvin on Thursday, February 17, that would startle and amaze the world.
The Knorr went exploring first, placing herself neatly into position above the site where a previous expedition, in 1972, had detected decisive hints o
f strange goings-on below. Instruments aboard a submersible device owned by the Scripps Institution of Oceanography, Woods Hole’s congenially competitive opposite number on the Pacific coast, which had been towed along that year through the 8,500-foot-deep, pitch-dark, and near-ice-cold waters over the ridge, had detected two strange spikes. One was of temperature, which had inexplicably risen—no more than a fifth of a degree Celsius or so, but it had risen nonetheless. Moreover, the spike was detected a hundred feet and more above the seabed, suggesting the presence of an upward gush of something hot, most likely water. The other spike was a sudden increase in dissolved iron and sulfur, and in just the place where the temperature made its own sudden rise.
The Knorr, using new and highly accurate maps made as part of the secret U.S. Navy magnetism researches, first sent down three sound beacons, transponders the pilots named Sleepy, Dopey, and Bashful. They would lie doggo on the seabed and emit signals to help keep on target any vehicles that the Woods Hole scientists sent down into the blackness of the deep sea.
The first vehicle was an unmanned two-ton, hundred-thousand-dollar steel-caged contraption named ANGUS (for Acoustically Navigated Geophysical Underwater System), which had powerful strobe lights, a collection of thermometers, and, most critically, high-definition cameras. Late on the afternoon of Tuesday, August 15, as computer-controlled propellers kept the Knorr above from drifting off target, a giant crane lowered the ANGUS downward, directly above the ridgeline. It took two hours to pay out 8,250 feet of twinned wire cables.
While the ANGUS was then electronically ordered to keep her position by communicating with the three transponders, the boom operator up on the mother ship was commanded to raise and lower the cables so as to keep the costly vehicle from hitting the seafloor. Then, fifteen feet above the seabed, the ANGUS switched on her powerful strobe lights, and then her array of cameras, and began to move, snapping one photograph of the bottom every ten seconds.
After six hours into the first watch, by which time the ANGUS had covered five miles, the needles on the many dials in the Knorr’s control room suddenly quivered upward for nearly three minutes, as the seawater became briefly hotter and hotter. It was a temperature anomaly, perhaps a rise of a fifth of a degree Celsius. Then the dials quivered back downward, as the temperature cooled just as rapidly. The ANGUS hovered above the Rise for another six hours, until a signal came that the film had run out. The ANGUS was winched carefully to the surface, her crew now agog to see what the three thousand photographs showed.
The developers worked through the morning, the pictures snatched from their hands as the sheets emerged from the fixing baths. Hundreds upon hundreds showed nothing other than rocks and darkness. But the photos from the spot where the ANGUS had recorded the temperature anomaly showed something very different, something quite unexpected. For down there, strobe-lit in the abyssal night, was a sudden abundance of wholly unanticipated life. Creatures were to be seen, living creatures, growing in the dark; oblivious to the cold, to the dark, and to the skull-crushing, hull-crushing, life-denying pressure tonnages of the two miles of seawater above.
There were just thirteen pictures of interest, but they showed something quite amazing, images that left the biologists aboard openmouthed with astonished delight: hundreds, maybe thousands of completely unexpected clams and mussels, living where no creature had the right or duty or supposed ability to be alive. The water here was blue and misty. The bivalves were apparently in good health, brightly colored, fronded, and evidently alive. How could this be? There were no nutrients. No light. No sun. And yet these creatures existed, here, on the floor of the sea—enigmatic and evidently eternal, the fact of their presence profoundly puzzling, and aching for an answer.
Just as the final pictures were being examined—and after the thirteen-image orgy of fascination, the next fifteen hundred images showed coils of glassy lavas changing to pillow piles of dull basalts, and nothing else at all—the other Woods Hole vessel, the Lulu, broke the horizon.
Frantic radio messages were sent out: Could the Alvin dive the next morning? Did she have the ability to dive that deep? Were there crewmen able and available to descend eight thousand feet, in a vessel that only recently had been upgraded with a new titanium sphere to hold the crew, to dive that deep?
To each inquiry, the answer was an unqualified yes. So the Lulu moved close in, and then positioned herself directly over the spot where the thirteen relevant pictures had been taken. Crane operators lifted the little Alvin up and over the gunwales and down onto the surface of the warm blue sea. It was Thursday, February 17. Three crewmen clambered in and strapped themselves onto the well-worn seats inside the cramped and damp little craft. Jack Donnelly was the craft’s pilot; two marine scientists, Jack Corliss and Tjeerd van Andel, were the observers.
Donnelly closed the hatch and flooded the air tanks, and the water closed over their heads. The cables were released, and the craft began to head downward at a stately hundred feet a minute. Within no more than three minutes, darkness had quite enveloped them; through the porthole there was just the faintest glimmer of the pale blue of the surface; and then, with the dark loom of the mother ship’s hull barely distinct, it faded away, too. The pilot switched on the powerful strobes.
He had seven thrusters with which to adjust his position, his heading, his attitude. It took an hour and a half of weaving and bobbing to reach bottom—where, to Donnelly’s delight, he found they were a mere five hundred feet from the target. He gunned his motors, adjusted his thrusters, and according to an official account of the expedition, “they entered another world.”
The lava fields below them were crisscrossed by cracks, and billowing up from the cracks in shimmering clouds were endless gushings of what the sensor probes showed to be very hot water. The shimmering itself was mesmerizing—but just a few feet away, the hot water mixed with the bitterly cold seawater, precipitating certain chemicals that turned the color to a powdery blue as they settled heavily on the seafloor, staining the surrounding rocks with crystals of deep umber.
This was spectacular in itself, and Jack Corliss, a geologist, was seeing before his very eyes confirmation of his theory that hydrothermal vents clearly did exist, which further supported the presence of spreading ridges beneath the sea, and which would lead to the creation of new ocean floor.
Then he cried out in astonishment, and asked a young woman named Debra Stakes, in the Lulu’s control room two miles above, “Wait—isn’t the deep ocean supposed to be like a desert?” Stakes patiently replied that, yes, this was what was believed. To ask her so basic a question strained credulity—it was as if an astronaut had asked if it was true there was no oxygen in space. “But,” spluttered an evidently flabbergasted Corliss, “there’s all these animals down here!”
They had stumbled onto a huge and densely populated biological community, in a part of the planet where life was previously thought to be entirely impossible. This turned out to be only one of four such fields they found that session, each different, each pullulating with robust displays of living existence. There were enormous clams and crabs, and creatures on long stalks, like dandelions. There was an octopus of a kind never seen before, and scores of eyeless shrimp. There were forests of waving tube worms, some of them seven feet tall, licking hungrily at the waters, seeming to suck nutrients from it.
The three crewmen were quite stunned, and noted that these creatures, illuminated for the first time by the strobes, did not run for cover or dive for shelter. They just sat there, pulsating with life.
Back in the 1970s the Alvin, though not as technologically sophisticated as today, had grappling arms and sample bottles, so while the crew’s air supply remained intact, and the pilot kept his craft on station, the two scientists delicately plucked clutches of living specimens from this newfound world, and sucked water into bottles for analysis up above. They had to get answers to a series of hitherto unimagined questions: What were these creatures? What were they doing here? How were the
y living? What were they eating? The Pacific Ocean swiftly became the nexus for a set of quite fundamental inquiries that had never been either imagined or supposed before.
When the trio broke the surface hours later, they had animals with them, among them a huge white clam bigger than Corliss’s two hands. They had scores of new photographs. And they had water samples. When they opened the bottles, they were hit by the unmistakable odor of rotten eggs. The water was clearly heavy with dissolved solids, its odor suggesting the presence of the element normally seen as a yellow powder around volcanic vents: sulfur.
John Edmond, the young Scots geochemist who had come out from MIT to be aboard the Lulu for this expedition, remembered the ecstatic moment of realization that was born of this particular chemical find. For he realized that whatever the importance of the vents in the story of the formation of the ocean floor (whatever the geological significance, in other words), the presence of animals and plants and, crucially, of sulfur, was more significant still: for this told him and his colleagues vastly important things about the origins of life itself.
The biology team immediately knew that the relatively complex creatures they had found below must be feeding on something. Logic told them that whatever that something was, something lower down the food chain, was likely to be more primitive than the creatures that were doing the feeding. Most probably the foodstuff consisted of bacteria, of some kind. So, somewhere in these hot streams of water, logic said, there had to exist some very primitive living creatures that could somehow reproduce themselves and so serve as the very base, and an endlessly replenished base, of the planetary food chain. Whatever these creatures were, they had no apparent need for sunlight, or for oxygen, or for any of the other chemical or physical components commonly connected with the endowment of the vital force. Such bacteria, if that is what they were, probably originated in places and circumstances like these newfound hydrothermal vents of the Pacific.
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