Page:Physical Geography of the Sea and its Meteorology.djvu/346

320 there. In the deep sea there are no abrading processes at work; neither frosts nor rains are felt there, and the force of gravitation is so paralyzed there that it cannot use half its power, as on dry land, in tearing the overhanging rock from the precipice and casting it down into the valley below.

594. The offices of animalculæ.—Hitherto we have, in imagination, been disposed to regard the waters of the sea as a great cushion, placed between the air and the bottom of the ocean, to protect and defend it from these abrading agencies of the atmosphere. The geological clock may we thought, strike new periods; its hands may point to era after era; but, so long as the ocean remains in Its basin, so long as its bottom is covered with blue water, so long must the deep furrows and strong contrasts in the solid crust below stand out boldly, rugged, ragged, and grandly. Nothing can fill up the hollows there; no agent now at work, that we know of, can descend into its depths, and level off the floors of the sea. But it now seems that we forgot the myriads of animalculæ that make the surface of the sea sparkle and glow with life: they are secreting from its surface solid matter for the very purpose of filling up those cavities below. These little marine insects build their habitations at the surface, and when they die, their remains, in vast multitudes, sink down and settle upon the bottom. They are the atoms of which mountains are formed—plains spread out. Our marl- beds, the clay in our river-bottoms, large portions of many of the great basins of the earth, even flinty rocks are composed of the remains of just such little creatures as these, which the ingenuity of Brooke has enabled us to fish up from the depth of nearly four miles (two thousand feet) below the sea-level. These Foraminifera, 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 be sent to cast up from the bottom of the sea for man's use.

595. The study of them profitable.—The study of these "sunless treasures," recovered with so much ingenuity from the rich bottom of the sea, suggests new views concerning the physical economy of the ocean. It not only leads us into the workshops of the inhabitants of the sea— showing us through their nurseries and cemeteries, and enabling us to study their economy—but it