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In this article from National Geographic, the author describes the ongoing effort to map and explore the ocean floor.
By Samuel W. Matthews
A round faced, somewhat roly-poly man lies on his stomach by a small view port inside a black, cigar-shaped craft slowly nosing on wheels through its own cone of light flooding the ocean floor. A portable hair dryer blows warm air across his neck, to prevent cramps and keep his breath from clouding the port.
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He has been here many times before—a civilian oceanographer, though this is a U. S. Navy submersible with nuclear power. His name is Bruce Heezen (pronounced HAY-zen); he is one of the world's best known marine geologists. At 50 he has personally mapped more of the earth's surface than anyone before him. And here in the cold North Atlantic in 1977, he is soon to die of a heart attack.
In 1947, 30 summers before, Heezen was a geology student working at Woods Hole Oceanographic Institution in Massachusetts under a gruff, tireless geophysicist named Maurice Ewing. Ewing had been at Woods Hole all during the war, helping to develop sonar and other instruments such as the bathythermograph, which could take a temperature profile of successively deeper layers of the sea. Shortly he would head a new laboratory at Columbia University in New York, which was to become today's renowned Lamont-Doherty Geological Observatory.
On the Woods Hole sailing ship Atlantis,”Doc” Ewing went to sea as often as he could, trying to learn more about the structure of the floor of the Atlantic by dropping TNT charges and recording the echoes. That summer he had use of the Atlantis to explore the Mid-Atlantic Ridge, with support from the National Geographic Society. Young Bruce Heezen sailed with him, as did another student, Frank Press, who years later would become presidential science adviser and today heads the National Academy of Sciences.
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East from Bermuda toward the Azores they went. Their depth-sounder, the most powerful yet sent to sea, first showed irregular terrain, then an absolutely flat abyssal plain, smooth as a vast mud flat 2,900 fathoms (17,400 feet) below the surface.
Two days later Atlantis found itself over bumpy foothills, then, in mid-ocean, over a wild and jagged realm of mountains, rank on rank of them, broken by huge valleys and canyons. The depth-sounder showed peaks six, eight, ten thousand feet tall—all a mile and more below the sea's surface.
They were over the ridge; they zigzagged back and forth across it for several weeks, sounding and taking dredge samples of bare, seemingly volcanic rocks. It was a far different landscape from the broad, high steppe Maury had described; it was the high barrier Challenger's temperature data and Meteor's soundings had shown must exist.
Ewing went back a number of times, but not for several more years—until Bruce Heezen began mapping the ocean floor, a lifelong task—did it become clear just what they had found.
The Mid-Atlantic Ridge he charted resembled the back of a huge crocodile. It rose more than 10,000 feet in places and was broken by great offsets.
Heezen and Marie Tharp, his drafting assistant, turned all the echo-sounding transects and depth recordings they could gather together, from all the ship tracks and oceanographic centers of the world, into seabottom profiles. Then they melded the profiles into physiographic diagrams, or sketch maps, that showed the ocean floor in three dimensions.
“When we began in 1952,” Heezen told me a decade later, “only a few such profiles had ever been drawn across the Atlantic.” He and Marie Tharp produced scores, then hundreds, finally thousands of them. In 1959 they published, with Maurice Ewing, The Floors of the Oceans: I. The North Atlantic. It accompanied the first of a series of maps that would encompass the globe.
Later their diagrams would be rendered by an Austrian mountain artist, Heinrich C. Berann, into more generalized, full-color map paintings. These were issued, one by one, by NATIONAL GEOGRAPHIC. To Heezen's great satisfaction (he was sometimes criticized by colleagues for extrapolating and drawing “poetic truths”), the maps blossomed on walls of schools and colleges—and in his colleagues' offices—the world over.
Before the first appeared, however, Marie Tharp had made a historic discovery of her own. She noticed that on profile after profile of the Mid-Atlantic Ridge, a deep V-shaped valley appeared to run along the very crest, or centerline. When she first ventured that this rift might extend the entire length of the range, Heezen didn't pay much attention. The idea seemed too vague, too farfetched.
About the same time Ewing and Press and other geologists at Lamont were restudying world earthquake records. Heezen began plotting the centers of the quakes on the detailed charts Marie Tharp was drawing.
The earthquakes followed the ridge crest—the path which Marie said held a rift valley. “It was as if a light suddenly went on,” Bruce Heezen said to me long afterward. “The rift indeed was there. The earthquakes were taking place along it.”
Belts of earthquakes had been charted down the Mid-Atlantic Ridge and along Indian Ocean and Pacific ridges—indeed, around the whole earth. Heezen realized that the quakes traced a far more extensive feature of the planet's hard surface than had ever been suspected: a massive scar 40,000 miles long, curving around the globe like the seam of a baseball. The Mid-Ocean Ridge, as Heezen named the system, now is known to cover as much of the earth's surface as all the continents put together.
It is volcanic and shaken by earthquakes. The fiery upthrusts of Iceland, the Azores, Tristan da Cunha, Réunion, the Galapagos are simply places where active volcanoes of the ridge system rise above water.
As more and more ocean expeditions proved that the central rift was really there, other facts emerged. Great east-west displacements cut across it; the Canadian geologist J. Tuzo Wilson named them transform faults. Many of the ridge quakes came from them. Not only was there high heat flow from within the earth along the ridge; most rocks dredged from its slopes were of fresh lava. Something was going on, something massive and basic.
Almost no sediments were found on the central slopes of the ridge. Indeed, and more mystifying, nowhere in the oceans was there as much or as old sediment as there should be if the oceans were as old as the earth itself. Where had the mud and ooze gone?
“I am reasonably certain,” oceanographer Roger Revelle was to say long after, “that Maurice Ewing went to his grave believing that somewhere in the deep sea there was a place where sediments of all geologic ages, back to one or two billion years, had been deposited one on top of the other.”
Yet nothing from the ocean floors, neither sediments nor bedrock, has yet been found older than about 200 million years. Were the continents in fact drifting, bulldozing off the sediments as they went?
About 1910 both a U. S. geologist, Frank B. Taylor, and a German meteorologist, Alfred Wegener, had proposed continental drift as a serious possibility. The idea was still being laughed at by many geologists in 1960. But at the same time, in 1959 and 1960, a few bold theorists were beginning to put forward a wholly new idea: Was the seafloor itself moving, carrying the continents with it? Were the oceans growing wider?
Geologist Harry H. Hess of Princeton University and Robert S. Dietz, a Navy oceanographer, theorized that the seafloor might be spreading from the central rift system. Hess called his landmark paper “an essay in geopoetry.”
Proof came swiftly, in a tide of discoveries all through the 1960s. The major proof was as unexpected as the notion that the oceans were widening.
The earth is a magnet. Its magnetic field controls the compass needle. Its rocks, chiefly those that cooled from molten magmas, act like frozen compasses; they show the earth's magnetism as it existed when the rocks solidified, layer after layer.
Ever since World War II, earth scientists had been studying lava beds on land. In the early 1960s they discovered that the earth's magnetic field has reversed many times in geologic history. Its north and south magnetic poles have flip-flopped.
When ships towed magnetometers across the oceans, curious striped patterns emerged. In 1963 two Cambridge University physicists, Frederick J. Vine and Drummond H. Matthews, and independently a Canadian, L. W. Morley, proposed that the ocean floors might be, in effect, giant recordings of earth's magnetic history. What's more, the successive stripes of reversed magnetism proved that the seafloor was indeed in motion—spreading in both directions from the center of the ridge.
Much more proof soon came from scientists at Lamont, working under Doc Ewing: Walter Pitman, James Heirtzler, Neil Opdyke, Xavier Le Pichon, Lynn Sykes. They compared magnetic patterns from different parts of the world, assigned dates to seafloor profiles, checked them against core samples, studied earthquake zones. “It was a time as exciting as any in the history of geology,” Jim Heirtzler told me years later.
More proof came from the seafloor itself. In the 1960s an effort to drill a sampling hole totally through the outer crust of the earth, the so-called Mohole, had aborted because of soaring costs. But the Mohole Project gave birth in turn to the Deep Sea Drilling Project (DSDP). Using a specially designed oceangoing drill ship, Glomar Challenger, the DSDP began in 1968 to probe and sample the seafloor deeper than ever before.
From the third drilling leg came confirmation of seafloor spreading. Off the hump of Brazil, in mid-Atlantic, cores brought up from either side of the ridge showed progressively greater ages the farther out they were taken. The Atlantic was widening by nearly an inch a year—in a man's lifetime, by as much as his height.
Glomar Challenger has gone on drilling for more than 13 years. Among its remarkable discoveries:
None of the oceans, even the oldest corner of the Pacific (the northwest), holds rock or sediment older than 200 million years.
In those 200 million years, less than a twentieth of earth's total age, parts of the seafloor have traveled thousands of miles.
The Mediterranean Sea has totally dried up, then refilled—perhaps more than once—within the past 12 million years.
Earth's past climate, through ice ages and long warm spells between, can be read and mapped from seafloor cores.
Roger Revelle, who has been deeply involved in the DSDP since its inception, has termed the program “one of the great achievements in the entire history of the earth sciences.”
A bulbous little white-hulled submarine named Alvin, scarcely bigger than a milk truck, has carried scientists into rifts in the earth's skin in both the Atlantic and Pacific. As a ship of discovery, in this age of exploration, it has done as much as Glomar Challenger to open new frontiers.
In July 1974, southwest of the island of São Miguel in the Azores, Alvin took Jim Heirtzler and other U. S. geologists 2,800 meters (9,100 feet) down to the central rift of the Mid-Atlantic Ridge. The dives were a key part of Project FAMOUS—French-American Mid-Ocean Undersea Study.
One of the younger scientists with Heirtzler's team was Robert D. Ballard; he had dived the year before at the Azores site in the French bathyscaph Archimède, a cumbersome undersea dirigible filled with aviation gasoline for buoyancy.
“When we first laid eyes on the glassy black, obviously fresh lava on the floor of the rift, it was as if there in our floodlights lay the true birthplace of the earth's crust,” Ballard has described those dives to me.
Pillowlike blobs and fractured tubes of black lava appeared to have been formed perhaps only a few centuries ago—an eye blink in geologic time. But no actual eruptions were seen taking place.
A decade earlier, in 1963 off the southern shore of Iceland, a new island named Surtsey had risen amid steam and ash from a seabed vent. Similar eruptions had occurred in the Azores in 1957, from a seabed volcano off Faial, and in 1961 at Tristan da Cunha. One is happening today at the southeast end of the Hawaiian chain, where a new island aborning, named Loihi, already stands some 8,800 feet above the seafloor with its top still 3,220 feet underwater.
Early in 1981, on a less violent seafloor, I learned firsthand what it is like to visit this new world. Off St. Croix in the U. S. Virgin Islands, under more than 3,000 feet of the Caribbean Sea, I sat cross-legged and cramped inside Alvin's seven-foot-wide pressure sphere, bending awkwardly to peer through a tiny Plexiglas view port at a flood-lit patch of dun-colored ooze.
The dive on which I accompanied Woods Hole electronics specialist Jim Akens and pilot George Ellis was to test a new ultrasensitive TV camera. “Silicon intensified,” they said knowingly. “Single-frame scan, 200,000 ASA equivalent.”
To me this was so much space jargon ... and then, music of space!
From a loudspeaker inside Alvin came an eerie ululation, a high-pitched Star Wars tremolo. We were hearing an image being recorded, then transmitted as a high-speed sonic signal to the sub's tender far above us.
The picture that would result was of a prosaic test target, a canvas panel painted with black and white squares. As Alvin rose from the bottom, rose silently and surprisingly fast, the target vanished from our view ports. But it remained, shrinking and dimming yet still discernible, on a miniature video screen above our heads in the sphere.
For me this was an experience of a lifetime. It was also an oceanographic milestone: Alvin was making the largest images of the deep seabed ever recorded, three-quarters of an acre at a time, in swaths 210 feet across. Its newest electronic wizardry was vastly broadening scientists' ability to see landscapes that have been shrouded in utter darkness and crushing pressure since the oceans themselves were born.
Ocean-floor plates collide, shift along giant faults, or crack and spread apart.
Two narrow, water-filled splits on the flanks of continents—the Gulf of California and the Red Sea—are oceans of the future just beginning to open, marine geologists say. Their basins are widening; heat comes up from below their floors.
In Mexico's Gulf of California great volumes of sediment carried down by the Colorado River mask the seabed rifting. Someday that rift may rip north, open a seaway through Nevada, and break away much of California as an island.
In the Red Sea, in several deep basins or holes, a different sort of mud exists. Not only is it hot—more than 60°C (140°F)—but it contains incredible amounts of minerals: silver, lead, zinc, copper, iron, and others. The top 30 feet of ooze in one of these basins, the Atlantis II Deep discovered by Woods Hole in the early 1960s, is potentially worth billions of dollars. Though commercial interest has been great, exploitation has been held back by legal and technical factors.
Ever since the first Challenger's cruise a century ago, it has been known that potato-size lumps rich in manganese and iron cover wide areas of the ocean floor, almost as thick as cobblestones. The nodules also hold copper, nickel, and cobalt. All that is needed is to lower a dredge and scoop them up.
The twin mysteries of exactly how these nodules form, and what keeps most of them unburied by seafloor ooze, remain to be solved. But careful estimates, particularly in mid-Pacific, show that enough exist to supply the entire world's needs for manganese, an important ingredient of steel, indefinitely; they are being formed on the ocean floor faster than they could be mined.
Giant firms have gone into international partnerships to plan and test methods for recovering this sea-bottom bonanza. Inability of the world's nations to agree on a Law of the Sea treaty, however, has delayed the start of deep-sea mining for more than ten years. But it will surely come, for the stakes are huge.
When seafloor spreading and magma upwelling were first recognized in the 1960s, geologists soon speculated that other minerals—extracted from deep in the crust by hot-water circulation—might be deposited along the mid-ocean rifts.
In Project FAMOUS, the French found an inactive vent surrounded by mineral deposits. Elsewhere along the Mid-Atlantic Ridge to the south, ships of the National Oceanic and Atmospheric Administration (NOAA) had earlier photographed a hydrothermal field. But it was not until 1979 that explorers of the eastern Pacific floor came face to face with minerals actually spewing from vents in the seabed.
Alvin, from its ungainly twin-hulled tender Lulu, had been diving north of the Galapagos Islands, on a rift where warm springs and strange colonies of life had been discovered two years before. Now the submersible had come north to a site on the East Pacific Rise near latitude 21° North.
“The first dives were unbelievable,” said Bob Ballard, who has traveled along more of the sea-bottom rifts than any other man on earth. “Here were these fountains of black or white material, like smoke, billowing from crevices and hollow rock pillars along the rifts. They made me think of Pittsburgh's smokestacks a generation ago.
“We drove Alvin up to one of the black smokers. Our claw thrust a plastic heat probe into the vent. The temperature recorder in the sub went off scale. Then we saw the plastic rod itself begin to melt, to droop like taffy. It didn't take long to realize Alvin's portholes might not stand such temperature [later calculated to be above 350°C—650°F]. We backed off in a hurry!”
More cautiously, time after time, Alvin's pilots and scientists nosed as close as they dared to other such geysers, made film and television images, and brought up samples of bright-colored minerals—sulfides and oxides of copper, iron, and zinc.
The fact of hydrothermal mineral formation in the oceans, which earlier was simply theory, is one more milestone discovery. It opens the way for more confident prospecting on land, and someday for mining the seabed itself. For the oceans, it is now clear, will inevitably be man's next mother lode for many of the natural resources he must have.
Today the United States draws 12 percent of its domestic crude oil from offshore wells—in the Gulf of Mexico, off California and Alaska. Soon it may tap its Atlantic shelf as well. Worldwide, a fifth of all oil and gas now comes from under the oceans.
Finding it, extracting it, and bringing it ashore safely have spawned extraordinary new industrial tools and techniques: Drill platforms taller than the Washington Monument stand amid the smashing waves of the North Sea; floating rigs ride on hulls submerged far under the surface; storage tanks, ship-loading terminals, and pipelines rest on the seafloor itself, from Persian Gulf to South China Sea to Gulf of Mexico.
All this too has happened largely in the past 30 years. The offshore oil industry depends on the ability to “see” rock layers deep within the sea bottom, using seismic echoes, computers, neutron emitters, heat probes, and gas sniffers.
The oil wells offshore, and the tankers that endlessly plow the oceans, bring great dangers as well. The chances of polluting the seas, possibly causing irreversible damage to their life forms and the shores they wash, grow with every offshore discovery, every supertanker leaving port.
Capt. Jacques-Yves Cousteau, roaming the world's seas for the past 31 years in his Calypso, now finds tar balls and other oil traces wherever he goes. “The oceans are sick and in trouble,” he says grimly.
Oceanographers in these 30 years have learned almost as much about the waters of the seas, and how they move, as they have about the vast mountain ranges of the seafloor.
When World War II ended, the charts of surface currents, wind patterns, tides, and wave patterns were the legacy of centuries of shipmasters' lore, of Matthew Maury's “Sailing Directions,” of sealed bottles cast adrift during pioneering cruises of research ships, but primarily of data gathered by competing—and often warring—navies.
Today the charts have been largely redrawn by instruments developed for peaceful research. With buoys that broadcast from mid-ocean for years and floats that drift great distances at constant depths beneath the surface, with hydrophones that pick up sonic signals from afar, with long-distance aircraft and cloud-piercing satellites that record sea ice and warm currents from space, physical oceanographers have refined their concepts of ocean circulation.
It was known that cold water from the polar regions creeps slowly at great depth toward the Equator, to replace warm surface currents, such as the Gulf Stream, that carry the sun's heat to high latitudes. In these few decades, however, it has been learned just how far north Antarctic bottom water reaches—to the northern limits of the Atlantic, Pacific, and Indian Oceans.
Massive currents and countercurrents beneath them flow in opposite directions along the Equator and the edges of continents. They help the oceans turn over and mix in as little time as a thousand years—an important control over climate.
In studying the North Atlantic, Bruce Heezen and Maurice Ewing recognized the tracks of tremendous undersea mud avalanches, called turbidity currents. The slides explained many things: why there are giant undersea ravines and valleys, such as the Hudson Canyon off New York; why submarine cables to Europe broke; why sand—a shallow-water substance—could come up in core samples taken far offshore. Heezen and Ewing analyzed one specific slide, set off by an earthquake in 1929 on the Grand Banks of Newfoundland, that broke more than a dozen transatlantic cables, one after the other.
In recent years drift buoys and satellite pictures have confirmed that the Gulf Stream is far from a smooth, straight river. Instead it meanders, twists, even forms great loops and eddies as it carries its load of tropical heat from the Caribbean to warm northern Europe.
In 1973 the United States and Britain joined in a project named MODE (Mid-Ocean Dynamics Experiment) to detect and track the great eddies of Atlantic water swirling slowly across a 270-mile-wide patch of ocean between Bermuda and Florida. Again in 1977-78, American, British, Soviet, Canadian, French, and West German oceanographers cooperated in an even larger program, called POLYMODE, in several areas of the Atlantic.
From such studies it became apparent that as much as 99 percent of all the energy in the motion of the oceans may be involved in eddies. Yet within these massive movements, distinct layers may be recognizable even after moving great distances.
“One, south of Bermuda, was so salty that its water could only have come from the Mediterranean,” Dr. Thomas Rossby of the University of Rhode Island, one of the U. S. designers of MODE and POLYMODE, told me. “Yet the layer, some 60 miles across and 1,640 feet thick, retained its identity all the way across the Atlantic.”
Woods Hole researchers have marked and tracked strange rings breaking off the Gulf Stream, seeking their cause and dynamics. Occasionally a slow whirl will totally enclose a pocket of either colder or warmer water, like a huge life ring or standpipe revolving in the sea. Fish and other life will not leave one type of water for the other, but stay within their natural revolving swimming pool as long as it remains unbroken.
Scripps Institution of Oceanography in California has long taken the Pacific as its lake, logging hundreds of voyages of discovery. Its ships found great fractures in the eastern Pacific floor, and in the north and west sounded the Aleutian, Japan, and Philippine Trenches, and, deepest of all, the Mariana Trench.
Thor Heyerdahl drifted with Kon-Tiki west from South America on the South Equatorial Current, 4,000 miles to the Tuamotu Islands. Scripps scientists traced the equally massive Cromwell Current flowing eastbound beneath it, to wash cold water up against the volcanic Galapagos Islands and support the fantastic, isolated life forms that Charles Darwin saw there.
The north-flowing Peru, or Humboldt, Current and upwelling of deep, cold water along the western flank of South America feed one of the richest fisheries in the world. But the region is subject to vagaries of atmospheric and oceanic forces thousands of miles away. Occasionally a great mass of warm water invades from the north and blankets the upwelling. Then, in those dread times called El Niño (The Child), the Peruvian fish catch fails and the world faces a shortage of protein for animal feed—and, ultimately, human sustenance.
In long, air-conditioned storage rooms at Scripps and Lamont stand rack after rack of cores—cylindrical tubes of mud and clay, sand and rock. These are taken from the seafloor by sharp-edged pipes dropped like bombs from oceanographic ships or brought up through Glomar Challenger's drill pipe.
Maurice Ewing, in a day when a single core sample ten feet long was a treasure that might take a year to analyze and fully write up, confounded his colleagues by bringing home cores by the scores, then by the hundreds, every time his Vema and Robert D. Conrad docked from world cruises.
But the results in new knowledge were immediate and dramatic; every other oceanographic institution was soon to emulate him. Then came the years of the Deep Sea Drilling Project, and the cores proliferated even faster.
“A competent marine geologist can read down the length of a seabed core and tell you the state of the ocean surface over a million years, and from that the earth's changing climate,” Lamont-Doherty's Dr. James D. Hays told me a few years ago.
By examining under microscopes the skeletons of tiny marine organisms—foraminifera, radiolarians, and such—in the cores, Dr. Hays and his colleagues can read the temperature of the sea surface when the creatures lived, then died and drifted down in a slow, constant rain to the seabed. They can tell as well the amount of ice in the world—how much fresh water, fallen as snow, remained locked up in ice caps and glaciers in those dim past ages.
They have known, for example, that about 65 million years ago, at the end of the Cretaceous geologic period, a sudden catastrophic extinction of surface-dwelling ocean life occurred. It happened very close to the time that the dinosaurs, equally mysteriously, died out on land.
In May 1980 Glomar Challenger brought up 655 feet of core from a 70-million-year-old ridge in the Atlantic off South Africa. In it the shipboard scientists found a clear record of that “boundary event.” A layer only 23 feet thick, datable by fossils, showed that the mass extinction took place in less than 100,000 years, within 500,000 years of the time the dinosaurs were gone. Sea-surface creatures that previously had thrived disappeared, leaving only a few species of minute plants and animals. It took several million years for the diversity of ocean life to reappear.
Studies of sedimentary layers on land in Italy, Denmark, and Spain, show the same sudden kill-off. Coincidentally in 1980, chemical studies of those layers revealed abnormally high amounts of exotic elements such as iridium, arsenic, and antimony.
The conclusion reached by some scientists, among them Nobel laureate Luis Alvarez and his son Walter, of the University of California at Berkeley, is that the planet was struck by an asteroid or comet as big as six miles across. Such a collision would have thrown vast quantities of dust into the atmosphere and scattered traces of heavy metals worldwide. The screening of sunlight from the land and sea for several years could have led to a massive kill of plant and animal species. “The lights went out, and that stopped the food chain,” says Luis Alvarez.
Marine geologist Cesare Emiliani of the University of Miami in Florida, however, believes that the asteroid fell into the ocean and caused a sudden temperature rise. “This,” he says, “could have brought the selective extinction of the dinosaurs and other animal and plant groups.”
Other researchers speculate instead that continental drift may have suddenly changed ocean circulation and killed off the sensitive Cretaceous life forms. The Arctic basin, blocked from the infant North Atlantic, may have suddenly released cold, relatively fresh water into the highly salty young sea to the south, and the shock to life there could have wiped out much of it. Climate around the Northern Hemisphere could have cooled enough to undo plant life on land, and thus the dinosaurs.
Not just long-term climate but day-to-day, week-by-week weather patterns are affected decisively by sea conditions, meteorologists are learning. “The bad North American winters of 1976-77 and 1977-78 are related to ocean-surface temperature changes in the North Pacific,” climatologist Jerome Namias of Scripps has told me.
When the jet stream over the Pacific changed in 1976, Dr. Namias said, California suffered winter drought, while paralyzing cold and snows gripped the Northeast. Three years later, just the opposite happened: California and the Northwest were deluged by rain and snow while the East went bare.
Changes in currents and cold-water upwellings along the flanks of continents produce drastic changes in fisheries, and the vital resource they provide for millions of people. El Niño disrupts the Peruvian fish catch for years at a time. Upwelling along the Arabian Peninsula, the shores of Pakistan and India, and elsewhere supports great fish populations as well. Should such upwellings fail, or should the monsoons controlled by the sun and the seas change, millions of people would go hungry.
Blooms of algae and other plankton, some causing the so-called red tides, kill or nourish pelagic fish. Conversely, the steady decline in whale populations over a century of more and more efficient hunting by whaling fleets has brought an apparent increase in the drifting meadows of shrimplike krill, on which the great whales graze.
There is so much krill in Antarctic waters, some experts say, that an efficient and controlled harvest on a sustained-yield basis could produce more food for the hungry world than all its fisheries put together. The only trouble is, not many people have developed a taste for krill. But the Japanese, for one, are freezing, drying, grinding, and otherwise preparing it for human consumption. In Tokyo's 50-acre Tsukiji fish market, I wandered among long tables covered with krill, krill flour, krill paste, dried and frozen krill hard to tell from shrimp.
Modern fishing fleets are marvels of efficiency. Freezerships serve the catchers, which swarm around fishing grounds. Danger of overfishing and irreversibly depleting stocks worries many nations. The extension of national boundaries 200 nautical miles offshore in the 1970s was largely impelled by the drive to protect ocean fishing.
At the same time, efforts to “farm” fish and other seafood have burgeoned. The Japanese cultivate oysters, shrimp, prawns, abalones, and fish of many varieties for food. Today China, as well, is fast expanding its mariculture—kelp, for example, is grown offshore like corn, and sea cucumbers, a sort of giant slug the Chinese relish, are harvested from the bottom. More food can be taken from an acre of seawater than from an equal area of farmland.
For centuries the Chinese have grown fish in farm ponds. U. S. scientists have inspected communes that grow three or more species of fish layer above layer in the same waters. “At one such fish farm near Shanghai,” Woods Hole biologist John H. Ryther reports, “carp swim through the ponds, some subsisting on grass and other vegetation cuttings thrown in, some on plankton fertilized by the manure of commune animals such as ducks and pigs, and others on bottom-dwelling mollusks. A many-storied food factory!”
With scientists from half a dozen U. S. institutions I met the NOAA vessel Oceanographer in Shanghai in 1980, the first U. S. government ship to visit China in more than 30 years. It joined Chinese research vessels in measuring the quantity and content of sediment carried down the caramel-colored Yangtze to the East China Sea. The Yangtze and Yellow Rivers together discharge almost as much silt as do all the rivers of North and South America—four times as much material each year as lies in the Great Wall of China. Their flow provides direct evidence of the slow, inexorable wearing away of the continents into the oceans.
In recent years, marine biologists have discovered new types of sea life almost with every expedition. With midwater nets they solved the mystery of the deep scattering layers, which had puzzled operators of sonar and depth-sounders in wartime—mysterious blankets or surfaces that moved upward at night, descended deeper by day. They consist of masses of light-sensitive plankton, small fish, and shrimplike crustaceans, living and moving just at the lower limit of sunlight's penetration in the oceans.
Submersibles such as Alvin, diving through such a layer, passed other forms that carry their own headlights, luminescent organs for either attraction or defense. To the scientists falling through them, as to William Beebe in the 1930s, they seemed like lighted snow drifting upward.
On the Galapagos Rift, and again at 21° North, the explorers found not only new species—possibly even a new phylum—but also an entirely new system of life, one not dependent on sunlight at all.
In warm water rising from rift vents, bacteria in amazing multitudes grow—metabolize—on inorganic chemicals, mainly hydrogen sulfide. This chemosynthesis, as biologists call it, takes the place of photosynthesis, the process of organic growth powered by the energy in sunlight.
The hordes of worms, crabs, clams, mussels, and other creatures discovered around the vents form a life system unknown in shallower water or on land. The discovery has been hailed by Woods Hole biologist Holger W. Jannasch as “so fundamental that something like it may occur only once in a scientist's lifetime.”
Ocean exploration in this remarkable generation has been carried on not only by scientists. Development of self-contained underwater breathing apparatus—scuba—by pioneers such as Jacques-Yves Cousteau opened the way for thousands of laymen to prowl the upper layers of the sea, breathing as freely as if above water.
Man thus entered the water world, and learned to breathe strange mixtures of oxygen and exotic gases. For extended periods, saturation dives, undersea refuges and living quarters were needed. Habitats such as Cousteau's Conshelfs in the Mediterranean and Red Seas, the U. S. Tektite in the Caribbean, and Sealabs in the Atlantic and Pacific expanded divers' ability to remain at depth for days, then weeks at a time, and provided laboratories in the deep.
As vehicles and habitats multiplied and grew more sophisticated, so also did man's eyes, ears, and other means of investigating and recording the unknowns in the seas.
Echo sounders, gravity recorders, magnetometers, heat sensors—all have been employed within the ocean and from above it, to learn more of its secrets. Photography has been joined by television, and early TV systems have now led to supersensitive solid-state devices—cameras without film—that can pick up, sharpen, and record the dimmest images in the abyss.
Sound has proved to be indispensable to science in the sea. How far can sound be detected? In 1960 a test by Lamont picked up off Bermuda a depth-charge blast detonated off Australia, 11,000 miles away. There is a deep sound channel in all the oceans, a layer varying from 2,000 to 4,000 feet down, from which sound waves cannot escape. Instead they bounce back and forth within the layer, traveling great distances as if in a huge speaking tube.
On and under the seafloor, equally incredible advances have been made. Glomar Challenger was limited in early years to drilling only as deep as one drill bit would last; then bit and drill pipe had to be withdrawn. The holes that struck hard rock rarely exceeded a few hundred feet.
But engineers soon overcame that problem. Guided by a sonic reflector on a steel funnel implanted in the seabed, Challenger now can withdraw and change a bit and put it back down the same hole, thousands of feet below. Development of a hydraulic piston corer in the past three years has enabled deeper sampling of soft sediments without disturbing them by the rotating drill pipe. The result will be far more detailed knowledge of the earth's recent geologic past.
And that is only the beginning. The next stage may use a much larger and more capable drill ship—the Glomar Explorer, built by Howard Hughes for the CIA to attempt to lift a Soviet submarine from the deep Pacific floor. The new drill ship will extend man's ability to probe the deep sediments of the continental margins, thought to be the storehouse of substantial oil and gas pools.
Yet in its 13 ½ years the Deep Sea Drilling Project has literally done little more than scratch the seafloor. To date, some 530 sites have been drilled, one for every 270,000 square miles of ocean—an area the size of Texas or the island of Borneo. “How much would we know,” asks Roger Revelle, “about the Texas plains or Borneo jungle from just one hole drilled blind from a dirigible above the clouds?”
Likewise a new generation of research submersibles is on the way, robots that will carry no men but, instead, their eyes and ears as well as other sensors into the depths. They will be far more efficient, say their developers, than such Model T craft as Alvin, which has now made more than 1,100 dives, a truly remarkable achievement.
At the Naval Ocean Systems Centers in California and Hawaii, I met the creators of unmanned exploring and working craft that propel themselves in the depths, controlled by tethers from “doghouses” lowered and powered by cables from the surface. Soon, say their builders, such craft will transmit images of what they see back over gossamer strands of glass, fiber-optic cables so fine that five miles will fit into a canister scarcely the size of a coffee can.
Bob Ballard is hard at work on such a new unmanned system. He calls it Argo, for the craft that Jason and the Argonauts sailed in search of the Golden Fleece. In partnership with the U. S. Navy and NASA, Woods Hole has received government funds to begin building this successor to Alvin.
“A pilot-scientist aboard a surface ship will sit before a bank of TV screens,” Ballard envisions. “Far below him, ‘flying’ at the end of a cable some 100 feet above the bottom, an unmanned exploring craft will carry supersensitive imaging cameras and lights, capable of recording as much as four acres of seafloor at once.”
This new deep-seeing vehicle, Argo, will enable the scientist to project his eyes—his mind—into the abyss in perfect safety and with virtually no time limit on his “dives.” Should Argo spot something of interest, such as an undersea hot-water oasis or active volcanic vent, a smaller, self-propelled vehicle, Jason, can be sent forth to take a closer look or gather specimens of the new discovery, using claws or other samplers.
Argo will thus be an extension of the scientist's eyes and hands as he sits on the surface—or even in his laboratory thousands of miles away, watching the televised images transmitted by satellite. When he tires or goes to lunch, another can take his place.
For those who still must go down in the sea themselves, other new devices already exist or are under development. Ungainly diving suits nicknamed Jim and Wasp permit industrial divers as well as scientists to stand and work more than a thousand feet down, breathing under one-atmosphere pressure as if at sea level. Marriages between submarine and diving suit are being developed for the oil industry as it works in deeper and deeper waters. Likewise, there are surface ships under test that may change ocean science even further.
Off Hawaii I rode the experimental ship Kaimalino, which the Navy terms an SSP—stable semisubmerged platform. Basically a helicopter pad on twin submerged hulls, it can race at more than 20 knots through high seas with almost no roll or pitch, offering a new breed of research and rescue craft.
Basic science goes on across the world's seas in increasingly more sophisticated ships. Soviet research vessels that ply every year to stations in the Antarctic are the size of small ocean liners.
Aircraft are increasingly used, as in the Atlantic Tropical Experiment and MONEX, the monsoon-tracking part of the current Global Weather Experiment, crisscrossing the oceans gathering data on sea-and-atmosphere interaction.
Energy from the oceans: The idea has fascinated men since the ancient Egyptians built tidal mills. Today, surging tides drive power plants in France, the U.S.S.R., and China. Canada and the U. S. have long studied tide potential in Passamaquoddy Bay on the Maine-New Brunswick border. Huge floating turbines, windmills, and other devices are on drawing boards to tap the power of trade winds, waves, and currents in the open sea.
And off Hawaii's Kona coast since 1979, sea trials have taken place to extract solar energy from the upper layer of the ocean.
In the tropics, sunstruck surface water may be 40°F or more warmer than water 3,000 feet below. In a process named OTEC—Ocean Thermal Energy Conversion—huge power plants would use this temperature differential to drive turbines; the electricity generated could be transmitted ashore by cables or used to extract hydrogen as fuel from seawater.
Industrial firms such as Lockheed, TRW, and others are vigorously promoting OTEC; development is funded by the Department of Energy. Though costly, OTEC could provide fuelless and unfailing power to cities and islands in tropical regions, say its proponents. Others point to unsolved problems of size, siting, and technology (the cold-water pipe for a full-scale OTEC plant, hanging half a mile deep, might be 80 feet in diameter).
And in a day of drastically curtailed federal budgets, such major projects as OTEC, deep-sea drilling, and ocean-scanning satellites now face cancellation or long delay.
If the oceans indeed are, as Law of the Sea (LOS) proponents in the United Nations proclaimed a decade ago, the “common heritage of mankind,” they also face the risk of enclosure suffered by the English commons at the opening of the industrial revolution—village grazing lands divided up and fenced off for private ownership. That, say LOS advocates such as Elliot Richardson, former U. S. Ambassador to the UN, would be a common disaster for all nations.
But equally important, if not more so, continued study of the seas by world scientists may bring new discoveries, exceeding even those of the past three decades.
“We may come to understand the basic interconnections between great natural phenomena,” predicts James Heirtzler of Woods Hole, “seafloor spreading, movements under the earth's crust, reversals of magnetism, volcanic and earthquake activity, changes of sea level, and the major climate changes that bring on the ice ages.”
Such a “unified earth theory” would rank with Einstein's theory of relativity and Darwin's on evolution among the truly great scientific advances in man's short time span on this ancient, water-mantled planet.
Source: National Geographic, December 1981.
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Exploration, Deep-Sea; Mid-Atlantic Ridge
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