Each of these great ocean valleys rises in a series of terraces to the sides of the Old and New Worlds respectively. The course of the western valley, which lies off the United States and the West India Islands, has been traced as far south as to the Equator. The terraces of the eastern valley rise from the depths of the ocean to the western coasts of Europe and Africa. Off the coast of Africa they rise into a series of lofty and rugged summits, which we call Madeira, the Cape Verd, and the Canary Isles; and the whole system culminates in the Peak of Teneriffe in the last-named group. That peak is two miles and one-third above the level of the sea. The lowest point yet sounded in the bed of the Atlantic is five miles and a third below that level. The whole mountain system of the Atlantic basin, therefore, extends to upwards of seven miles in vertical height, or higher than any of the mountains of the globe are above the level of the sea.
By bringing up specimens from the depth of the Atlantic, and studying them under the microscope, it has been ascertained that the bed of the ocean is covered with very minute shells, which lie on the bottom as lightly as gossamer. The microscope has not detected a single particle of sand or gravel among these little mites of shells. This fact proves that quiet reigns in the depths of the sea: that as in the air ocean there is a region of perpetual calm, "above the clouds;" so in the ocean of waters there is a region where perpetual calm prevails, beneath the troubled waves. There is not motion enough to abrade these very delicate organisms, nor current enough to sweep them about, or to mix with them a grain of the finest sand.
It may be that the myriads of animalculeswhich make thesea glow with life are secreting from it solid matter which is destined to fill up the cavities below. They furnish the atoms of which mountains are formed and plains are spread out. Our marl-beds, the clay in our river-bottoms, large portionsof many of the great basins of the Earth, even flinty rocks, are composed of the remains of just such minute animals as those which have been fished up from a depth of three miles below the sea-level. These creatures, therefore, when living, may have been preparing the ingredients for the fruitful soil of a land that some earthquake or upheaval, in ages far away in the future, may yet raise up from the bottom of the sea for the use of man.
WORDS
ascertained, found.
cavities, hollow places.
converge, draw near to each other.
culminating, crowning. destined, appointed. detected, discovered. garniture, embellishment. gossamer, cobweb. ingredients, elements.
organisms, structures. panorama, comprehensive view. perpetual, constant.
separates, keeps apart. submarine, under the sea. summits, peaks. surveyed, examined.
temperature, degree of heat.
transport, convey.
NOTES
① Telegraph Plateau.-So called because on it were laid the submarine telegraph cables between Ireland and America in 1865 and 1866. Many other cables now follow the same route.
② Higher than Mont Blanc.-This is the illustration used by Professor Wyville Thompson,in his work entitled The Depths of the Sea . But Arnold Guyot says that the level of the Atlantic bed appears to be more uniform than has hitherto been supposed, "extensive plains and huge table-lands being its predominating features."③ Animal"cules, very small animals. It was at one time supposed that there was noanimal life at the bottom of the deep sea,-that those little animals whose remains are found there lived only near the surface of the ocean. Recent investigations have shown this to be a mistake. Life has been found at a depth of three miles, and is now believed to exist even in the deepest parts.
QUESTIONS
Of what does the bed of the ocean consist? What part of the Atlantic has been surveyed? By whom? What plain stretches across the northern part of the basin? On what do the British Isles stand? What effect has this on their climate? Why? What extends southward from the middle of TelegraphPlateau? What is there on either side of the central continent? Where is the deepest part of the Atlantic? If we could stand there, how far should we be below the sea-level? By what should we be surrounded? What would the Bermudas appear to be? And the Azores? Where does the whole Atlantic mountain system culminate? What is its extent in vertical height? With what is the bed of the ocean covered? What shows that quiet reigns in the depths of the sea? Of what are the animalcules found in the bed of the ocean the elements?