National Geographic : 1981 Dec
seven-tenths of the earth, salt bitter, oft storm racked, most of it pitch dark and near freezing. Averaging two and a half miles deep the world around, it holds, by some estimates, 99 percent of the life-supporting space on our planet. It separates the great landmasses of the In 30 extraordinary years, scientists have opened the NEW WORLD OF THE OCEAN By SAMUEL W. MATTHEWS SENIOR ASSISTANT EDITOR I immensity, and mystery, and power. So it is to most of us, even in this heyday of science. Man has lived by the ocean and voyaged upon it for thousands of years. Yet only in the past three decades, one human generation, have we begun to see, to map, and dimly to comprehend the true nature, shape, and complexity of the world ocean. It is a startling prospect indeed. In 1950, only a few years after World War II, Rachel Carson published The Sea Around Us. She told of what science knew then about the ocean-its origins, currents, unseen depths, and strange life forms. But many a chapter of her evocative review end ed on a similar note: "At present we do not know .... No one now can say...." By 1981 many of those blanks were being filled in. Instruments not even invented globe, affects their weather, provides their life-sustaining rain, receives their off-flowing waters and poisons. It surges to the pull of the moon and sun, swirls to the spin of the earth, and carries in its currents the energy of solar heat and the chill of polar ice. I have lived beside the sea, sailed upon it by catboat and Navy cruiser, crossed the Atlantic, Pacific, and Indian Oceans, flown above the Arctic, and dived to the floor of the Caribbean Sea in a tiny submersible. Nonetheless I know almost nothing deep and certain about the ocean. Its essence is 792 three decades ago now measure the vast movements and forces at work in the ocean. Undersea vehicles carry explorers thou sands of feet deep to towering mountain ranges and yawning rift valleys. Satellite sensors and seismic stethoscopes take the pulse of earth itself. Consider just a few of the things we now know about the ocean, after these 30 historic years of exploration: * The seafloor-that nearly 72 percent of the planet's crust covered by salt water-has been "seen" with sound waves and mapped in fine detail for the first time. (Its mind boggling features appear on the World Ocean Floor map with this issue.) * The seabed is constantly being created and destroyed; the oceans are opening or closing; the continents around them are drifting, car ried on giant rafts. New crust oozes up in molten form from below, solidifies, and moves outward; old, cold crust dives into deep trenches and is reabsorbed into the interior of the earth. * * As the seafloor splits and moves apart, earthquakes jar the planet and volcanic mountains grow in the ocean. Minerals are born and deposited in the seabed: oil be neath deep sediments, metals from spewing hot springs, others from seawater itself. * Ocean waters flow and overturn in unsus pected ways, carrying energy absorbed from the sun, regulating the earth's daily weather and long-term climate. They wash away and ominously retain-man's most danger ous wastes. They nurture blooms of micro scopic life, meadows of drifting plankton, entire fisheries. * Life, which began in the sea, still reveals new and wondrous forms there, from bacte ria flourishing in utterly dark depths to lar vae of fish and crustaceans nourished in sun-blessed shallows, from myriad krill and anchovies to territorial sharks and intelli gent porpoises and gentle, singing whales, largest of earth's creatures. Man's driving curiosity about what lies in and under the oceans is nothing new, of course. We inherit it from our earliest hu man ancestors who ventured to catch and eat a fish, open an oyster, or drift out from shore upon a floating log. *The author wrote about "This Changing Earth" in the January 1973 GEOGRAPHIC.