Page:Physical Geography of the Sea and its Meteorology.djvu/348

322 an hour and even more. Every square foot of the earth's crust at the bottom of a four-knot current 3000 fathoms deep would have no less than 506,880—in round numbers, half a million—of such columns of water daily dragging, and rubbing, and scouring, and chafing over it, under a continuous pressure of 648 tons. What would the bottom of the sea have to be made of to withstand such erosion? Water running with such a velocity, and with the friction upon the bottom which such a pressure would create, would in time wear away the thickest bed, though made of the hardest adamant. Why, then, has not the bottom of the sea been worn away? Why have not its currents cut through the solid crust in which its billows are rocked, and ripped out from the bowels of the earth the masses of incandescent, molten matter which geologists tell us lie pent up and boiling there?

598. Why they cannot chafe it.—If the currents of the sea, with this four-mile velocity at the surface, and this hundreds of tons pressure on the bottom, were permitted to chafe against its bed, the Atlantic, instead of being two miles deep and 3000 miles broad, would, we may imagine, have been long ago cut down into a narrow channel that might have been as the same ocean turned up on edge, and measuring two miles broad and 3000 deep. But had it been so cut, the proportion of land and water surface would have been destroyed, and the winds, for lack of area to play upon, could not have sucked up from the sea vapours for the rains, and the face of the earth would have become as a desert without water. Now there is a reason why such changes should not take place, why the currents should not uproot nor score the deep bed of the ocean, why they should not throw out of adjustment any physical arrangement whatever: because, in the presence of everlasting wisdom, a compass was set upon the face of the deep; because its waters were measured in the hollow of the Almighty hand; because bars and doors were set to stay its proud waves; and because, ''when He gave to the sea His decree that its waters should not pass His command. He laid the foundations of the world so fast that they should not he removed for ever.''

599. What it consists of.—By bringing up specimens from the depth of the ocean, and studying them through the microscope, it has been ascertained that the bed of the ocean is lined with the microscopic remains of its own dead, with marine feculences which lie on the bottom as lightly as gossamer. How frail yet