CHAPTER ITHE OCEAN AND ITS ORIGIN

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Lookingat the land, we divide the surface of the earth into eastern and western hemispheres; but looking at the water, we make an opposite classification. Encircle the globe in your library with a rubber band, so that it cuts across South America from about Porto Alegre to Lima on one side, and through southern Siam and the northernmost of the Philippine Islands on the other, and you make hemispheres, the northern of which (with London at its center) contains almost all the land of the globe, while the southern (with New Zealand as its central point) is almost entirely water, Australia, and the narrow southern half of South America being the only lands of consequence in its whole area. Observing the map in this way, noticing that, besides nearly a complete half-world of water south of your rubber equator, much of the northern hemisphere also is afloat, you are willing to believe the assertion that there is almost three times as much of the outside of the earth hidden under the waves as appears above them. The estimate in round numbers is one hundred and fifty million square (statute) miles of ocean surface, as compared with about fifty million square miles of land on the globe.

To the people whose speculations in geography are the oldest that have come down to us, the earth seemed to be an island around which was perpetually flowing a river with no further shore visible. Beyond it, they thought, lay the abodes of the dead. This river, as the source of all other rivers and waters, was deified by the early Greeks and placed among their highest gods as Oceanus, whence our word “ocean.” Accompanying, or belonging to him, there grew up, in the fertile imagination of that poetic people, a large company of gods and goddesses, while men hid their absence of real knowledge by peopling the deep with quaint monsters.

“The word for ‘ocean’ (mare) in the Latin tongue means, by derivation, a desert, and the Greeks spoke of it as ‘the barren brine.’”

Over these old fables we need not linger. All the myths and guesswork that went before history represented the sea as older than the land, and told how creation began by lifting the earth above the universal waste of waters. The story in Genesis is only one of many such stories.

A QUIET SEA, AND THE SUN AT MIDNIGHT.From a photograph.

Scientific men believe that when our planet first went circling swiftly in its orbit it was a glowing, globular mass of fiery vapors; but as time passed, the icy chill of space slowly cooled these vapors, and chemical changes steadily modified, sorted, and solidified the materials into the beginnings of the present form and character, until at lastwatercame into existence. This must have been at first in the form of a thick envelop of heated vapors, impregnated with gases, that inwrapped the globe in a darkness lit only by its own fires.

After that, when further changes had come about,—let us picture it,—what deluges of rain were poured out of and down through those murky clouds where thunders bellowed and lightnings warred! At first all the rains that fell must have been turned to steam again; but by and by thesteady downpour cooled the shaping globe so that all the water was not vaporized, but some stayed as a liquid where it fell, and this increased in amount more and more, until finally, between the hissing core of the half-hardened planet and the dense clouds which kept out all the sunlight, there rolled the heated waves of the first ocean—an ocean broken only by the earliest ridges, like chains of islands, marking the skeletons of the continents that were to follow—an ocean sending up ceaseless volumes of steam to form new clouds.

EATING AWAY THE COAST.

Yet all the while the cooling of the planet went on. Now, when any heated substance cools it contracts, and the globe as a whole is no exception to the rule; but a sphere formed of so incompressible a substance as rock can shrink only by some sort of folding or displacement of its surface. Therefore, as the cooling of our globe proceeded, explosions and swellings constantly occurred at weak points or lines on or near the surface, where the prodigious strain forced a break. That these upheavals were most prominent and extended in the northern hemisphere is shown by the fact that the great masses and heights of land are grouped there; and the trend of mountain-ranges seems to show that the range of breakage and upheaval was in general in north-and-south lines. Elsewhere, and mainly in the southern hemisphere, broad areas of perhaps stiffer crust sank downward, making the vast depressions into which poured the waters of the primeval sea, and where our oceans still sway and roll.

SURF AT FORT DUMPLING, R. I.

All these changes, however, have been in the direction of insuring moreand more stability; and when the ocean water had thoroughly cooled, the very chill of its vast masses in the depths of the troughs assisted in the work, for the cold water, by more rapidly withdrawing their heat, caused the rocks beneath their basins to become denser, thicker, stronger, and consequently less liable to break or change, than were those rocks forming the foundations of the continents.

The moment it had shores to beat upon, that moment the ocean began to knock them to pieces under its pounding surf, and to grind the fragments so small that they could be drifted away, reassorted, and deposited wherever the water was sufficiently quiet to let them fall. The original rocks—chiefly granite—held the different forms of lime, magnesia, etc., to make the limestones; the silica to make the gritty sandstones; the alumina to make the clays; and so on. The sea not only was the agent to eat this old, rich crust to pieces and respread it into strata, but to sort out for us the materials to a considerable extent, laying down beds of limestone by themselves, and sandstone, shales, marl, etc., by themselves. It is probable, says Professor Shaler, that layers of rock twenty miles in thickness have thus been laid down on the gradually settling ocean floor, much of which has been raised again to form continental lands.

Hitherto we have spoken of the waters that surround the continents as if they formed one mass, as, practically, they do; but for convenience sake we may designate certain areas by separate names, which ought now to be defined. Thus the larger, more open spaces are known asoceans, and of these five are recognized, namely, Pacific, Atlantic, Indian, Arctic, and Antarctic. Parts or branches of these, more or less inclosed by land and usually comparatively shallow, are termedseas.

The Pacific Oceanis the largest, it alone covering more space than all the continents combined, having a breadth, east and west, of ten thousand miles (about the length of the Atlantic), and an area of seventy million square miles. The equator divides it into the North and South Pacific. The former is comparatively free from islands, and is inclosed northward by the approaching extremities of Alaska and Siberia; while the latter widens at the south into the boundless Antarctic Ocean. Its basin is a vast depression of fairly uniform depth, studded in the western part by island peaks,—the summits of submerged volcanic mountain-ranges. The name “Pacific,” or “Peaceful,” was given to it by Magalhaens (Magellan), its first navigator, in 1540(see Chapter IV), in his joy at having escaped from the tempestuous experience he had long endured in the South Atlantic. On the whole the Pacific deserves its name as compared with the Atlantic—a fact chiefly due to its great size. The term “South Sea” wasformerly much used for it, but English-speaking persons now usually mean by that phrase the island-studded district between Hawaii and Australia.

PERCÉ ROCK, IN THE GULF OF ST. LAWRENCE, SHOWING DESTRUCTION OF SHORE-ROCKS BY WATER.

The Atlanticcommemorates in its name the myth of Atlas and his island. Atlas seems to have been originally, among the Greeks, the name of the Peak of Tenerife, of which they had vague information from the earlierPhenician sea-wanderers. Then this was forgotten, and in place of the fact arose a myth of a Titan who stood upon a vast island in or beyond the “Western Sea,” called Atlantis. Legends of wars with its people form a part of the nebulous hero-story of the beginnings of Athens; and it is said to have sunk out of sight long before records began. There have always been those who believed this story founded upon fact, and only a few years ago a book was printed in the United States arguing that the tale was the history of a real land; but not only is there no literary or historical evidence that Atlantis had any firmer foundation than vague memories of the Cape Verd or Canary Islands, but every evidence of the geological condition and history of the eastern shores and bed of the middle Atlantic Ocean shows that no such convulsion as the destruction of this island calls for ever took place there, or that there was ever such a land to be submerged. The Atlantic occupies a long, winding, comparatively narrow trough, that measures about ten thousand miles north and south, from the ice of the Antarctic to the ice of the Arctic ocean, and has only a few islets south of Iceland, the Faroes and the Shetlands, which rise from a plateau stretching from Labrador to Great Britain, the higher points of which were probably above the water within comparatively recent geological times, possibly since man appeared upon the globe. The average depth of the Atlantic south of this ridge is about thirteen thousand feet, but greater depths are found along the African and American coasts, on each side of a long submerged ridge from which rise the isolated islands of Cape Verd, St. Helena, and Tristan da Cunha. The width from Norway to Greenland is only about eight hundred miles, but between Montevideo and Cape Town it is thirty-six hundred miles, and the average width is about three thousand miles. The shape and situation of the Atlantic make it the most stormy of the three great oceans, and it is the one where the phenomena of tides, currents, etc., are most prominently manifested, as we shall see. It is also the most frequented and best known, because it has been necessary to study it for the benefit of commerce.

The Indian Oceanis simply the extension of the vast southern water-zone northward of parallel 40°, south latitude, where, from the Cape of Good Hope to Tasmania, it is six thousand miles in width. At this line the depth suddenly decreases, as though the edge of a submerged Antarctic plateau defined the southerly rim of its basin there. This ocean contains several large and some groups of small islands, but these are mostly near the shore, and connected with the neighboring continent by shallow waters, showing that they rise from a submerged plateau. The average depth of the Indian Ocean is about fourteen thousand feet; its surface-water iswarmer and salter than that of any other; and its winds and weather are more regular and peaceful than in either the Atlantic or the North Pacific.

The Arctic Oceanis the well-defined body of water around and probably over the north pole. It is connected with the Pacific only by the narrow and very shallow Bering Strait, and with the Atlantic by comparatively narrow openings. It has been fairly well explored as far north as the parallel of 80°, and found to contain many islands; but it appears that there is great depth of water north of Spitzbergen and northeast of Greenland, making it probable that the trough of the Atlantic reaches to or beyond the pole itself. Most of its area is covered with drifting ice.

The Antarctic Oceanis regarded as the space of water within the Antarctic circle; but this is surrounded by a zone of deep ocean, unbroken almost half-way to the equator, except by the narrow southern part of South America and by New Zealand. It is an area, apparently rather shallow, of ice, fogs, and tempestuous gales, inclosing lands of unknown extent.

WAVE-WORN CLIFFS AND PEBBLE-BEACH AT ETRETAT, FRANCE.(FROM A PAINTING BY WILLIAM P. W. DANA.)

But these geographical distinctions are merely convenient methods of speech. After all, there is only one ocean “poured round all,” and its particles are incessantly changed in place and remingled by means of a world-wide system of tides and currents, the effect of which is to keep sea-water everywhere uniform in character and perfectly pure and healthful.

IN MID-OCEAN: A GREAT WAVE.

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