In exploring the Gulf for oil, therefore, geologists search for the salt domes where the larger oil fields are likely to lie. They use an instrument known as a magnetometer, which measures the variations in magnetic intensity brought about by the salt domes. Gravity meters also help locate the domes by measuring the variation in gravity near them, the specific gravity of salt being less than that of the surrounding sediments. The actual location and outline of the dome are discovered by seismographic exploration, which traces the inclination of the rock strata by recording the reflection of sound waves produced by dynamite explosions. These methods of exploration have been used on land for some years, but only since about 1945 have they been adapted to use in off-shore Gulf waters. The magnetometer has been so improved that it will map continuously while being towed behind a boat or carried in or suspended from a plane. A gravity meter can now be lowered rapidly to the bottom and readings made by remote control. (Once an operator had to descend with it in a diving bell.) Seismic crews may shoot off their dynamite charges and make continuous recordings while their boats are under way.
Despite all these improvements which allow exploration to proceed rapidly, it is no simple matter to obtain oil from undersea fields. Prospecting must be followed by the leasing of potential oil-producing areas, and then by drilling to see whether oil is actually there. Offshore drilling platforms rest on piles that must be driven as far as 250 feet into the floor of the Gulf to withstand the force of waves, especially during the season for hurricanes. Winds, storm waves, fogs, the corrosive gnawing of sea water upon metal structures—all these are hazards that must be faced and overcome. Yet the technical difficulties of far more extensive offshore operations than any now attempted do not discourage specialists in petroleum engineering.
So our search for mineral wealth often leads us back to the seas of ancient times—to the oil pressed from the bodies of fishes, seaweeds, and other forms of plant and animal life and then stored away in ancient rocks; to the rich brines hidden in subterranean pools where the fossil water of old seas still remains; to the layers of salts that are the mineral substances of those old seas laid down as a covering mantle over the continents. Perhaps in time, as we learn the chemical secrets of the corals and sponges and diatoms, we shall depend less on the stored wealth of prehistoric seas and shall go more and more directly to the ocean and the rocks now forming under its shallow waters.
The Encircling Sea
A sea from which birds travel not within a year,
so vast it is and fearful.
HOMER
TO THE ANCIENT GREEKS the ocean was an endless stream that flowed forever around the border of the world, ceaselessly turning upon itself like a wheel, the end of earth, the beginning of heaven. This ocean was boundless; it was infinite. If a person were to venture far out upon it—were such a course thinkable—he would pass through gathering darkness and obscuring fog and would come at last to a dreadful and chaotic blending of sea and sky, a place where whirlpools and yawning abysses waited to draw the traveler down into a dark world from which there was no return.
These ideas are found, in varying form, in much of the literature of the ten centuries before the Christian era, and in later years they keep recurring even through the greater part of the Middle Ages. To the Greeks the familiar Mediterranean was The Sea. Outside, bathing the periphery of the land world, was Oceanus. Perhaps somewhere in its uttermost expanse was the home of the gods and of departed spirits, the Elysian fields. So we meet the ideas of unattainable continents or of beautiful islands in the distant ocean, confusedly mingled with references to a bottomless gulf at the edge of the world—but always around the disc of the habitable world was the vast ocean, encircling all.
Perhaps some word-of-mouth tales of the mysterious northern world, filtering down by way of the early trade routes for amber and tin, colored the conceptions of the early legends, so that the boundary of the land world came to be pictured as a place of fog and storms and darkness. Homer’s Odyssey described the Cimmerians as dwelling in a distant realm of mist and darkness on the shores of Oceanus, and they told of the shepherds who lived in the land of the long day, where the paths of day and night were close. And again perhaps the early poets and historians derived some of their ideas of the ocean from the Phoenicians, whose craft roamed the shores of Europe, Asia, and Africa in search of gold, silver, gems, spices, and wood for their commerce with kings and emperors. It may well be that these sailor-merchants were the first ever to cross an ocean, but history does not record the fact. For at least 2000 years before Christ—probably longer—the flourishing trade of the Phoenicians was plied along the shores of the Red Sea to Syria, to Somaliland, to Arabia, even to India and perhaps to China. Herodotus wrote that they circumnavigated Africa from east to west about 600 B.C., reaching Egypt via the Straits of the Pillars and the Mediterranean. But the Phoenicians themselves said and wrote little or nothing of their voyagings, keeping their trade routes and the sources of their precious cargoes secret. So there are only the vaguest rumors, sketchily supported by archaeological findings, that the Phoenicians may have launched out into the open Pacific.
Nor are there anything but rumors and highly plausible suppositions that the Phoenicians, on their coastwise journeys along western Europe, may have sailed as far north as the Scandinavian peninsula and the Baltic, source of the precious amber. There are no definite traces of any such visits by them, and of course the Phoenicians have left no written record of any. Of one of their European voyages, however, there is a secondhand account. This was the expedition under Himlico of Carthage, which sailed northward along the European coast about the year 500 B.C. Himlico apparently wrote an account of this voyage, although his manuscript was not preserved. But his descriptions are quoted by the Roman Avienus, writing nearly a thousand years later. According to Avienus, Himlico painted a discouraging picture of the coastwise seas of Europe:
These seas can scarcely be sailed through in four months … no breeze drives the ship forward, so dead is the sluggish wind of this idle sea … There is much seaweed among the waves … the surface of the earth is barely covered by a little water … The monsters of the sea move continually hither and thither, and the wild beasts swim among the sluggish and slowly creeping ships.
Perhaps the ‘wild beasts’ are the whales of the Bay of Biscay, later to become a famous whaling ground; the shallow water areas that so impressed Himlico may have been the flats alternately exposed and covered by the ebb and flow of the great tides of the French coast—a strange phenomenon to one from the almost tide-less Mediterranean. But Himlico also had ideas of the open ocean to the west, if the account of Avienus is to be trusted: ‘Farther to the west from these Pillars there is boundless sea … None has sailed ships over these waters, because propelling winds are lacking on these deeps … likewise because darkness screens the light of day with a sort of clothing, and because a fog always conceals the sea.’ Whether these descriptive details are touches of Phoenician canniness or merely the old ideas reasserting themselves it is hard to say, but much the same conceptions appear again and again in later accounts, echoing down the centuries to the very threshold of modern times.
So far as historical records are concerned, the first great voyage of marine exploration was by Pytheas of Massilia about 330 B.C. Unfortunately his writings, including one called On the Ocean, are lost and their substance is preserved for us only in fragmentary quotations passed on by later writers. We know very little of the controlling circumstances of the northward voyage of this astronomer and geographer, but probably Pytheas wished to see how far the oecumene or land world extended, to learn the position of the Arctic Circle, and to see the land of midnight sun. Some of these things he may have heard of through the merchants who brought down tin and amber from the Baltic lands by the overland trade routes.
Since Pytheas was the first to use astronomical measurements to determine the geographic location of a place and in other ways had proved his competence
as an astronomer, he brought more than ordinary skill to an exploratory voyage. He seems to have sailed around Great Britain, to have reached the Shetland Islands, and then to have launched out into the open ocean to the north, coming at last to ‘Thule,’ the land of midnight sun. In this country, he is quoted as reporting, ‘the nights were very short, in some places two, in others three hours long, so that the sun rose again a short time after it had set.’ The country was inhabited by ‘barbarians’ who showed Pytheas ‘the place where the sun goes to rest.’ The location of ‘Thule’ is a point much disputed by later authorities, some believing it to have been Iceland, while others believe that Pytheas crossed the North Sea to Norway. Pytheas is also said to have described a ‘congealed sea’ lying north of Thule, which accords better with Iceland.
But the Dark Ages were settling down over the civilized world, and little of the knowledge of distant places acquired by Pytheas on his voyagings seems to have impressed the learned men who followed him. The geographer Posidonius wrote of the ocean that ‘stretched to infinity’ and from Rhodes he undertook a journey all the way to Gadir (Cadiz) to see the ocean, measure its tides, and determine the truth of the belief that the sun dropped with the hissing of a red-hot body into the great western sea.
Not for about 1200 years after Pytheas do we have another clear account of marine exploration—this time by the Norwegian Ottar. Ottar described his voyagings in northern seas to King Alfred, who recorded them in a straightforward narrative of geographic exploration strikingly free from sea monsters and other imaginary terrors. Ottar, on the basis of this account, was the first known explorer to round the North Cape, to enter the Polar or Barents Sea, and later to enter the White Sea. He found the coasts of these seas inhabited by people of whom he seems to have heard previously. According to the narrative, he went there ‘chiefly to explore the country, and for the sake of the walrus, for they have much valuable bone in their tusks.’ This voyage was probably made between A.D. 870 and 890.
Meanwhile the age of the Vikings had dawned. The beginning of their more important expeditions is usually considered to be the end of the eighth century. But long before that time they had visited other countries of northern Europe. ‘As early as the third century and until the close of the fifth century,’ wrote Fridtjof Nansen, ‘the roving Eruli sailed from Scandinavia, sometimes in company with Saxon pirates, over the seas of western Europe, ravaging the coasts of Gaul and Spain, and indeed penetrating in 455 into the Mediterranean as far as Lucca in Italy.’ As early as the sixth century the Vikings must have crossed the North Sea to the land of the Franks, and probably to southern Britain. They may have established themselves in Shetland by the beginning of the seventh century, and plundered the Hebrides and northwest Ireland about the same time. Later they sailed to the Faroes and to Iceland; in the last quarter of the tenth century they established two colonies in Greenland, and shortly thereafter they steered across the intervening Atlantic waters to North America. Of the place of these voyages in history Nansen writes:
The shipbuilding and seamanship of the Norwegians mark a new epoch in the history both of navigation and discovery, and with their voyages the knowledge of northern lands and waters was at once completely changed … We find accounts of these voyages of discovery in the old writings and sagas, a large part of which was put into writing in Iceland. A somber undercurrent runs through these narratives of voyages in unknown seas—the silent struggle of hardy men with ice, storms, cold, and want.
They had neither compass, nor astronomical instruments, nor any of the appliances of our time for finding their position at sea; they could only sail by the sun, moon, and stars, and it seems incomprehensible how for days and weeks, when these were invisible, they were able to find their course through fog and bad weather; but they found it, and in the open craft of the Norwegian Vikings, with their square sails, fared north and west over the whole ocean, from Novaya Zemlya and Spitsbergen to Greenland, Baffin Bay, Newfoundland, and North America. … It was not until five hundred years later that the ships of other nations were to make their way to the same regions.*
But only the vaguest rumors of any of these things had reached the ‘civilized world’ of the Mediterranean. While the sagas of the Norsemen were giving clear and factual directions for the passage across oceans, from known to unknown worlds, the writings of the scholars of the medieval world dealt still with that outermost encircling ocean, the dread Sea of Darkness. About the year 1154 the noted Arab geographer Edrisi wrote for the Norman king of Sicily, Roger II, a description of the earth, accompanied by 70 maps, which portrayed on the outside of all the known earth the Dark Sea, forming the limit of the world. He wrote of the sea about the British Isles that it is ‘impossible to penetrate very far into this ocean.’ He hinted at the existence of far islands but thought the approach to them difficult because of the ‘fog and deep darkness that prevails on this sea.’ The scholarly Adam of Bremen, writing in the eleventh century, knew of the existence of Greenland and Wineland as distant islands in the great ocean, but could not separate the reality from the old ideas of that sea, ‘infinite and fearful to behold, which encompasses the whole world,’ that ocean flowing ‘endlessly around the circle of the earth.’ And even the Norsemen themselves, as they discovered lands across the Atlantic, seem merely to have pushed back the boundaries of the place where still there began that outermost ocean, for the idea of the outer ocean surrounding the disc of the earth appears in such Northern chronicles as the Kings Mirror and the Heimskringla. And so over that Western Ocean into which Columbus and his men set out there hung still the legend of a dead and stagnant sea, of monsters and entrapping weeds, of fog and gloom and ever present danger.
Yet centuries before Columbus—no one knows how many centuries—men on the opposite side of the world had laid aside whatever fears the ocean may have inspired and were boldly sailing their craft across the Pacific. We know little of the hardships, the difficulties, and the fears that may have beset the Polynesian colonists—we know only that somehow they came from the mainland to those islands, remote from any shore. Perhaps the aspect of these central Pacific waters was kindlier than that of the North Atlantic—it must have been—for in their open canoes they entrusted themselves to the stars and the signposts of the sea and found their way from island to island.
We do not know when the first Polynesian voyages took place. Concerning the later ones, there is some evidence that the last important colonizing voyage to the Hawaiian Islands was made in the thirteenth century, and that about the middle of the fourteenth century a fleet from Tahiti permanently colonized New Zealand. But again, all those things were unknown in Europe, and long after the Polynesians had mastered the art of navigating unknown seas, the European sailors still regard the Pillars of Hercules as the gateway to a dreaded sea of darkness.
Once Columbus had shown the way to the West Indies and the Americas, once Balboa had seen the Pacific and Magellan had sailed around the globe, there arose, and long persisted, two new ideas. One concerned the existence of a northern passage by sea to Asia; the other had to do with a great southern continent generally believed to lie below the then-known lands.
Magellan, while sailing through the strait that now bears his name, had seen land to the south of him through all the thirty-seven days required for the passage through the strait. At night the lights of many fires glowed from the shores of this land, which Magellan named Tierra del Fuego—Land of Fires. He supposed that these were the near shores of that great land which the theoretical geographers had already decided should lie to the south.
Many voyagers after Magellan reported land they assumed to be outlying regions of the sought-for continent, but all proved to be islands. The locations of some, like Bouvet, were so indefinitely described that they were found and lost again many times before being definitely fixed on maps. Kerguelen believed firmly that the bleak, forbidding land he discovered in 1772 was the Southern Continent and so reported it to the French government. Wh
en, on a later voyage, he learned that he had found merely another island, Kerguelen unhappily named it ‘Isle of Desolation.’ Later geographers, however, gave his own name to it.
Discovery of the southern land was one of the objects of Captain Cook’s voyages, but instead of a continent, he discovered an ocean. By making an almost complete circumnavigation of the globe in high southern latitudes, Cook revealed the existence of a stormy ocean running completely around the earth south of Africa, Australia, and South America. Perhaps he believed that the islands of the South Sandwich group were part of the Antarctic mainland, but it is by no means sure that he was the first to see these or other islands of the Antarctic Ocean. American sealers had quite possibly been there before him, yet this chapter of Antarctic exploration contains many blank pages. The Yankee sealers did not want their competitors to find the rich sealing grounds, and they kept the details of their voyages secret. Evidently they had operated in the vicinity of the outer Antarctic islands for many years before the beginning of the nineteenth century, because most of the fur seals in these waters had been exterminated by 1820. It was in this year that the Antarctic continent was first sighted, by Captain N. B. Palmer in command of the Hero, one of a fleet of eight sealers from Connecticut ports. A century later, explorers were still making fresh discoveries about the nature of that Southern Continent, dreamed of by the old geographers, so long searched for, then branded a myth, and finally established as one of the great continental masses of the earth.
The Sea Around Us Page 23
