Ocean's Story; or, Triumphs of Thirty Centuries / Maritime Adventures, Achievements, Explorations, Discoveries and Inventions; and of the Rise and Progress of Ship-Building and Ocean Navigation, from the Ark to the Iron Steamships

by Frank B. Goodrich

CHAPTER LVIII.

OUR KNOWLEDGE OF THE EARTH AND SEA—HOW IT HAS INCREASED—THE EARTH THE DAUGHTER OF THE OCEAN—THE OPINION OF SCIENCE—THE MEAN DEPTH OF THE OCEAN—THE EXTENT OF THE OCEAN—ITS VOLUME—SPECIFIC GRAVITY OF SEA-WATER—CONSTITUTION OF SALT-WATER—THE SILVER IN THE SEA—THE WAVES OF THE SEA—THE CURRENTS OF THE OCEAN—THE TIDES—THE AQUARIUM—THE COMMERCE OF MODERN TIMES—THE SPREAD OF PEACE.

In the preceding pages the facts have been given in a comprehensive though succinct form, which enable us to see how, step by step, each one of which became possible only when those preceding had been taken. Mankind has gained a knowledge of the outlines of the sea; of the form of the earth itself; of the relative positions occupied by the water and the land; of their action upon each other, and thus the way has been prepared by the enterprise of preceding generations for the scientific methods of study which characterize the modern era. The adventurous voyagers of the early times, who, daring as they were, hardly were bold enough to venture in their open boats, propelled only by oars, out of the sight of land, could not be expected to conceive that it could be possible for men, like themselves, to ever become able to construct ships such as modern nations construct, in which, propelled by steam, voyages should be taken across oceans, and out of sight of land, their course over the trackless waters be guided with accuracy and certainty, to any desired point, by the compass and the observations of the motions of the stars.

By experiment and observation the entire aspect and conception of the ocean has been changed in modern times from that which prevailed in antiquity, or even more recently, until within the few past generations. Though much has been done, in the study of the ocean, toward obtaining a proper conception of its influence in the general economy of the globe, yet there is still much to be learned. Among the ancients it was generally declared in their cosmogonies that the solid portions of the world were produced by the ocean. "Water is the chief of all," says Pindar; "the earth is the daughter of ocean," is the mythological statement common to the primitive nations. Though this poetical expression was merely based upon a vague tradition, and can hardly be taken as the result of any methodical study of the earth, yet modern science tends to show that it is really true. The ocean has produced the solid land. The study of geology, the skilled inspection of the various strata of the land—the rocks, sand, clay, chalk, conglomerates—proves that the materials of the continents have been chiefly deposited at the bottom of the sea, and raised to their present position by the chemical or mechanical agencies which are constantly at work in the vast laboratory of nature.

Many rocks, as for instance the granites of Scandinavia, which were previously believed to have been projected in a molten and plastic state from the interior of the earth, where they had been subjected to the action of the intense heat supposed to exist in the centre of the earth, are now supposed to be in reality ancient sedimentary strata, slowly deposited by the sea, and upheaved by the contraction of the crust, or by some other force of upheaval acting from the centre. Upon the sides of mountains, or on their summits, now thousands of feet above the level of the ocean, unquestionable traces of the action of the sea can be found. And the scientific observer of to-day sees all about him evidences that the immense work of the creation of continents, commenced by the sea in the earliest periods of time, is to-day continuing without relaxation or intermission, and with such energy that even during the short course of a single life great changes can be seen to have been produced. Here and there a coast, subject to the beating of the serf, is seen to be slowly undermined, disintegrated, worn down and carried away, while in another place the material is deposited by the sea, and sandy beaches or promontories are built up. New rocks also, differing in appearance and constitution from those worn away, are formed. But beside this action of the sea upon the coasts, in constantly changing the configuration of the land, modern observation has shown us that animal life is an agent constantly at work within the sea itself, in the formation of new lands. The innumerable minute forms of life with which the sea swarms; the coral polyps, the shells, the sponges, and the animalculæ of all kinds, are constantly engaged in consuming the food they find, in reproducing themselves, and in dying. From the various matters brought down to the ocean by the rivers of the land, they secrete their shells or other coverings; and as generation after generation they die, these falling to the bottom form immense banks, or plains, which some future action of upheaval will bring above the surface to form the material for new continents or islands.

Thus while the ocean prepares the materials for the future continents in its bosom, it also furnishes the waters which wash away the lands already existing. To the thought of modern science the granite peaks, the snow-clad mountains, immovable and eternal as they seem, are constantly disintegrating, and partake, with every thing else in creation, the eternal round of change which is constantly going on. From the sea, by evaporation, rise the vapors which, condensing against the sides of the mountains, form the glaciers; and these, slowly sliding down toward the plains, are such efficient agents in wearing away the mountains, grinding up their solid rocks and preparing the gravel which the mountain streams distribute over the plains. From the sea the atmosphere receives the moisture destined to return in rain from the clouds; to feed the brooks whose union forms the rivers, destined again to return to the sea the waters it provided, and thus keep up, in a single, mighty and endless circulation, the waters of the globe.

Thus to the agency of the ocean we are indebted for our rivers, which have played such an important part in the geological history of the earth, in the distribution of the flora and fauna of various countries, and on the life of man himself. In the study also of the climates of the earth, and their effects upon life, we find the ocean bears a most important part. As the circulation of the atmosphere mingles the heated air from the equator with that of the frozen regions of the poles, so the currents of the ocean circulate about the earth, blending the contrasts of climate, and making a harmonious whole of all the different portions. Thus, instead of considering the ocean as the barren waste of desolation it appeared to the ancients, to the modern thinker the ocean has, layer by layer, deposited the land from its bosom, and now by its vapors provides the rains which support its vegetable life, upon which all other life depends, and creates the rivers and the springs, which play such an important part in the modification of the interior of continents, at the greatest distance from the sea.

The mean depth of the whole mass of the ocean waters of the globe is estimated at about three miles, since measurements have shown that the basins of the Atlantic and Northern Pacific are deeper than this by hundreds of thousands of fathoms. The extent covered by the surface of the ocean has been estimated at more than 145,000,000 of square miles, and with this estimate, the sea is calculated to form a volume of about two and one-half million billions of cubic yards, or about the five hundred and sixtieth part of the planet itself. The highest point of the land raised above the level of the sea is much less elevated than the bottom of the sea is depressed from the same level, so that the mass of the land above this level can be estimated only at about a fortieth part of the mass of the waters.