Facts the Challenger collected are still in use—among them, water-temperature readings showing that a high mountain barrier must indeed divide the Atlantic Ocean basin down its middle.
World War I interrupted ocean exploration, though not such developments as the submarine and echo depth-sounder. In the 1920s and 1930s scientific voyages resumed, such as those of Germany’s Meteor, trying to extract not only basic knowledge but also gold from seawater with which to pay war debts. And off Bermuda zoologist William Beebe and engineer Otis Barton descended in a steel ball on a cable, called a bathysphere, to view startling, headlight-carrying life forms half a mile down in the sea.
World War II opened the floodgates of discovery. In submarine warfare, in better ocean charts, in a multitude of developments from sonar to magnetic recorders, military needs led to new instruments and advances in marine hardware that would revolutionize what man knew of the ocean.
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.
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.
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 sea-bottom profiles. Then they melded the profiles into physiographic diagrams, or sketch maps, that showed the ocean floor in three dimensions.