“A whole lot of things sort of fell into place,” Edmond said. “We realized that regular seawater was mixing with something. It was a unique solution I had never seen before. We all started jumping up and down. We were dancing off the walls. It was chaos. It was so completely new and unexpected that everyone was fighting to dive in Alvin. There was so much to learn. It was a discovery cruise. It was like Columbus.”
The finds made that day confirmed one aspect of tectonic plate theory. But they also entirely upended the hitherto comfortable assumptions concerning the origins of life. For no longer were sunlight, chlorophyll, oxygen, and warmth considered necessarily essential for life’s beginnings. Another, and quite new, option had now revealed itself here in the Pacific Ocean. For whatever it was that lay at the base of this East Pacific Rise food chain (still undiscovered at this point, but surely to be found someday soon) had somehow come into being in this most inhospitable of environments. It had been born in what was, essentially, another version of the already much-vaunted primeval soup: liquid that in this case would soon be shown to be ferociously hot, was already known to be eternally dark and chemically rich, and was of the kind of sulfur-rich composition that was suspected to have existed at the volcanic dawn of the earth’s story.
The notion that life itself, that living cells prodded into life from simple amalgams of chemistry into some primitive beginnings of sentience, did begin in the hydrothermal vent ecosystems would swiftly set the biological world afire. The curious were about to have a field day.
A young woman named Colleen Cavanaugh was one of them. She was a biology student from Michigan, and she happened to be at Woods Hole just before the institution’s little submarine was discovering the vents. She had arrived there, innocently enough, to take a summer course on the mating habits of horseshoe crabs. But at the course end, her car broke down, and she never made it home to Michigan. Instead, she decided to complete her undergraduate degree in Boston, and was then invited back to Woods Hole (an hour away, and on the sea) in the summer of 1977. That was the so-called discovery year—except that Ms. Cavanaugh’s work was unrelated, and was concerned as it had been before with the love lives of horseshoe crabs.
But everyone in the sprawling campus of the Woods Hole laboratories seemed now to be talking about events five thousand miles away in the Pacific, and about the sensational finds that the Alvin had made the previous winter. People were talking about the geology, true. They were talking about the ocean ridges’ mineral potential, true. But they were talking most energetically about just how it was that clams, tube worms, subsea dandelions, and, yes, crabs (relatives of Cavanaugh’s crabs) managed to flourish as they did in the high-pressure darkness right beside scalding-hot vents.
Colleen Cavanaugh became a passionate believer that bacteria of some kind must provide the key to the story. It was she who would then go on to discover both the actual nature of the bacteria in these hydrothermal vents and, perhaps most crucially, the chemical process that they undertake to provide nourishment for the creatures that cluster beside them. She most famously enjoyed her epiphany by interrupting a classroom discussion on the biology of vent-living tube worms: the moment she heard the lecturer casually remark that the worms had crystals of sulfur inside them, she stood up and loudly asserted that it was “perfectly clear” that the creatures had to have sulfur-oxidizing bacteria inside them. Somehow these bacteria were manufacturing organic material (sustenance for the tube worms) out of inorganic building blocks. Making life, in other words, out of purely elemental whole cloth.
It is a process known as chemosynthesis. Not a new process—a remarkably prescient Russian musician turned chemist named Sergei Winogradsky, working in Saint Petersburg in the 1890s, had proposed the theory that some specialist bacteria could produce energy from purely inorganic materials, could then employ that energy to obtain carbon, and with that could produce sugars: organic material, in other words, the basis of life.
Cavanaugh, who would in time become a tenured professor at Harvard with her own eponymous laboratory, was eventually able to demonstrate that chemosynthesis was exactly what was happening in deep-sea hydrothermal vents. The tiny globules of sulfur found in the gut3 of a giant tube worm (one of the dauntingly large, six-foot-long, red-tipped creatures brought up from the deep) indicated to her that bacteria living inside the worm were able to create energy from the hydrogen sulfide that was dissolved in the vent’s hot-water gushes. They then would use that energy, just as Winogradsky so presciently suggested, to capture carbon from the methane and carbon dioxide also found in the water, and manufacture food on which the tube worms could feed.
It was a truly edge-of-your-seat scientific advance. Before this, the scientific community believed that all life ultimately demanded energy radiated from the sun, that the process of photosynthesis, in which light is an absolutely essential component, lay at the basis of all living existence. Winogradsky’s theorizing, and Cavanaugh’s impertinent epiphany and her work on the deep Pacific tube worm (Riftia pachyptila), showed beyond doubt that energy could be derived from within the earth itself, with no need whatsoever for any contribution from a distant star.
Colleen Cavanaugh announced the find in 1981, with a paper in Science, “Prokaryotic Cells in the Hydrothermal Vent Tube Worm Riftia pachyptila Jones: Possible Chemoautotrophic Symbionts.” It remains one of the milestones of modern science. And that it was derived from discoveries made by the Alvin in the Pacific Ocean underlines the formidable importance of the planet’s mightiest of seas.
All the other oceans have since been discovered to house hydrothermal vents. More than three hundred fifty clusters of vents have been found and seen since that first Alvin dive. It was swiftly realized that the water gushing up from them was seawater that had seeped down through cracks in the ridges, had been heated, and like a geyser out on the dry surface of the world, had erupted back outward again. This is not newly created water—rather, it is existing seawater recirculated through the ridges so the total volume of water in the seas remains constant. The recirculation is a massive planetary engine: all the world’s oceanic water is thought to circulate through these chains and clusters of vents about every ten years, and to leach out immense amounts of crustal chemistry into the deep sea as it does so.
Most of (but not all) the vents have been found along the rifts at the top of their various spreading ridges. Most have been given rather prosaic names, like those given to obscure stars or small asteroids. But some vents are so large and powerful that they have been given appropriately memorable titles: White City, Loki’s Castle, Bubbylon, Magic Mountain, Mounds and Microbes, Neptune’s Beard, Nibelungen, Salty Dawg. Not surprisingly, numerous international bodies have been established to coordinate and regulate ridge research—one of them born in 1992, when two ships arrived at the same mid-ocean site at the same time with plans to send submarines down to the very same ridge to look for the very same vent fields.
Though the role these vents play in the search for life’s origins is fascinating, another motivation for today’s activity over the deep-sea ridge lines is more economic—and that commercial interest was spawned by a second discovery that was made two years later, also by the Alvin, also in the Pacific, on the craft’s dive number 914. This was the dive that found, at the tops of the most active ridges, almighty “submarine towers,” the massive solid and semimetallic consequences of all the fluid gushings beneath. If dive 713 has become part of scientific legend, then dive 914 is best remembered for revealing the commercial possibilities behind that legend—and for offering the alluring hint of treasure, there for the picking, down in the world’s deep waters.
The Alvin had been kept busy in the months following her first vent discoveries. She performed twenty more dives north of the Galápagos, and then headed back through the Panama Canal to spend the rest of the year in the Caribbean, before heading home to Woods Hole. In 1978 she had more nip-and-tuck work done (much steel was replaced by titanium), to prolong her
working life and enable her to probe ever deeper and for longer periods of time. A second grabber arm was added so the scientists could seize more samples of the marvels waiting at the vents. And there were new cameras, new lights, and a basket at the bow to hold ever more samples.
Thus kitted out, she then performed a scattering of more workmanlike tasks (investigating nuclear waste dump sites off the New Jersey coast, for example) before heading back south to warmer waters, and then through the Panama Canal once again to the Pacific’s exceptionally active rift zones. She made two dozen further dives northeast of the Galápagos in the winter of 1979—during which time her crew discovered that the dandelion-like creatures below were actually specially adapted colonies of thousands of even tinier creatures known (when clumped together) as siphonophores, related to the jellyfish lookalike called a Portuguese man-o’-war. These beasts did not handle the pressure at the surface well, and exploded on deck or otherwise vanished, another indication of the vast amount of entirely new science that was being uncovered in this new hydrothermal universe.
It was in April that the Alvin headed north. Her mother ship, the Lulu, voyaged for eighteen hundred miles, carrying the Alvin up and onto the crest of the northern sector of the East Pacific Rise. She was assigned to a spot in the tropical seas at twenty-one degrees north latitude, within sight of the cliffs at the very tip of Baja California. Surfers were riding the waves here, oblivious to the work that was about to begin far offshore.
The Lulu’s cranes hoisted the fifteen tons of Alvin over the side. Dudley Foster, a thirty-three-year-old former navy pilot (who once said that the Alvin’s arm was an extension of his own, and that he wore the sub as part of his body), was in command. An American geologist and a French volcanologist were the observers. It was Saturday, April 21, 1979.
The Frenchman, Thierry Juteau, was aboard because of a curious discovery made nearby the year before by the French mini-submarine Cyana. Her crew had not encountered a vent, but they had dredged up a great number of tantalizing rock samples, including one more bizarre than most, which seemed to have assumed the form of a long, hollow metal tube glistening with crystals. These turned out to be precipitates of a zinc ore called sphalerite;4 there were traces of iron, copper, lead, and silver on the sides of the tube as well, suggesting both a vast trove of deep-ocean chemistry below and also the presence of the exceptionally hot water needed to dissolve it.
The Alvin descended quickly into the darkness, switching on her powerful new lights as the sunlight vanished. By mid-morning she was close to the bottom, and almost immediately spotted the white clams that are the most visible signature of a Pacific vent field. Dudley Foster turned the craft to follow the ever-thickening concentration of shells until, suddenly, quite without warning, he had to slam on his brakes.
Before him, staggering to see, was something that no human had ever witnessed before. Rising directly in front was a tall spire of dark rock, with what looked like a jagged crystal-fringed mouth at its top, from which gushed, without cease, a torrent of thick, black, coiling fluid, looking just like dark and oily smoke, belching upward as if from a ship charging full ahead or from a railway train racing down the line.
Foster nudged his craft closer—and found its considerable tonnage bucking and rearing under the immense water turbulence beside the edge of the fountain. For a moment he lost control, and the sub was knocked into the pillar, breaking it and widening the hole even more, and filling his viewing screen with pitch-black fluids that briefly blinded him. He steered frantically back into clear water and then turned to view what they had found. The three sat entirely mesmerized by the show. It was like watching a leak from a rogue oil well, with tens of thousands of gallons of pitch-black fuel coursing upward without end into the pristine sea.
After a few moments, the crewmen’s courage regained, their breathing rates stabilized, they advanced the sub slowly back toward the tower, this time with an electronic thermometer gripped tightly in the manipulator arm. Using the thrusters to keep the platform horizontal and moving in a straight line, they pushed a sensor gingerly into the liquid uprush—whereupon it promptly shot off scale, showing a temperature of more than 90 degrees Fahrenheit. No such figure had ever been experienced in such deeps. It had to be wrong. They tried again—the needle banged hard up against the end of the range again, and this time the instrument went dead.
Only when they got to the surface did they look at the thermometer and realize why. Its sensor tip had melted. The temperature of the smoker fluid—which they then determined on their next dive, with a thermometer capable of working in a blast furnace—was some 662 degrees. It was an incredible figure. If this was water, then it was hot enough to melt lead. Magnesium would soften, too, and so would tin. Sulfur would be almost at its boiling point.
This column of fluid clearly was not composed of water, at least not principally. The fluids were so intensely hot, the pressure so insanely high, that metals or their compounds had first been dissolved and extracted wholesale from within the material of the earth’s crust deep below. The upward-gushing fluids were most probably made up of considerable concentrations of dissolved compounds of gold, silver, iron, magnesium, lead, zinc, and tin. They could almost be thought of as a molten alloy of all these base metals, mixed with sulfur and seawater. And when this chemical-laden torrent suddenly confronted the ice-cold deep-sea waters, the base metals and the sulfur compounds almost instantaneously precipitated out of solution and created a bewildering smorgasbord of solids—either compounds of metals or else, in rare cases, clanging, shining shards of the wholly pure metals themselves.
These gathering masses of solids would then fold themselves out of the uprush and, as they fell to one side, still half-molten, would pile ever upward around the circumference of the gushing liquid column, like metallic stalagmites. As the gush continued, so the towers became ever taller and taller, until they could not stand under their own weight—or else until careless passing research submarines knocked into them. Towers like these could be built in a matter of hours, climbing skyward in the dark, and yet never (like the trials of Tantalus) quite making it upward beyond the limits imposed by physics and gravity, but instead slumping back onto the seafloor, for the ever-hopeful gusher to try again.
These towers on the East Pacific Rise were called black smokers, for obvious reasons—although this smoke is a precipitate of particulate metal rather than, as is traditional, combusted ash. Other huge underwater chimneys—soon to be discovered in the Atlantic Ocean and exhaling, by contrast, torrents of paler-colored fluids, and emerging at lower temperatures—turned out to be laden with calcium and barium. These quite reasonably came to be known as white smokers.
When heavy metal sulfides are caught up in the geysers of superheated water gushing from a submarine vent, huge but fragile towers of metallic minerals—black smokers—form and rise dozens of feet from the seabed, until they eventually collapse under their own weight.* [P. Rona/NOAA.]
Hundreds of smoker towers have been found in the years since. They have been found in all the expected places: along the summit traces of the ridges in the Indian and Atlantic Oceans and, most profligate of all, along the immense tracery of ridges and beside the ocean trenches and island arcs that mark the boundaries of the great Pacific tectonic plate.
Not surprisingly, it took no time at all for those in the mining business to realize the value of these gleaming pipes of crystalline metal compounds. And some of the towers are truly immense. One black smoker, named Godzilla, lying deep off the Pacific coast of Canada, could be watched as it grew fully one hundred fifty feet up from the seafloor, before it finally collapsed under its own mighty weight. And that mighty weight was made up not of coral or clams or crabs or tube worms, but of metallic compounds: sulfides, most commonly, of exploitable, minable, potentially salable metal.
Surveys have recently identified an alluring number of collapsed smoker pipes and vent crystals deposits, making what are now called seafloor massive su
lfide (SMS) deposit fields or sites. Eye-watering tonnages of copper, lead, and zinc sulfides, and ores of gold and silver, have been assayed in the glittering, meteorite-heavy, and metal-like SMS fragments that have already been dredged up or brought to the surface by Alvin-type submarines.
For years following the first finds, the world’s mining industry became intrigued with trying to work out how best to win these SMS deposits from the sea. But the companies’ enthusiasm was tempered by caution, and understandably so. The industry was already somewhat gun-shy, since it had been badly burned back in the 1960s by the commercial failure of the much-vaunted manganese nodule boom, in which billions of tons of mineral-rich pellets lying on the ultra-deep seafloor turned out to be far too costly to bring to the surface. SMS fields, by contrast, were richer in minerals and, as they lay on or beside mid-ocean ridges, were in much shallower waters. If only the technological challenges of getting at them could be met, and if the world price of these various metals remained high enough, then there was an absolute fortune waiting down there in the deep.
A Canadian firm called Nautilus Minerals has become the first in line to try to make a business out of the metal-laden ruins of old black smokers. It has identified two sites, both in the Pacific, both on the Ring of Fire. One is in the Bismarck Sea, just north of Papua New Guinea, halfway between the islands of New Ireland and New Britain, and thirty miles north of the infamous and unfortunate city of Rabaul.5 The other is on a ridge to the west of the Kingdom of Tonga. The means Nautilus has contrived to extract from these sites the hundreds of thousands of tons of metal ores suspected to lie two miles below are clever, cunning, and, in the view of some environmental groups, deserving of wide condemnation.