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.