But besides these things the bottom of the sea receives deposits of the remains of all kinds of shells, corals, and all sorts of marine creatures, great and small. As the countless myriads of the animals of the sea die, the shells with which they are covered, or the bones which form their framework, fall continually to the bottom of the oceanic gulfs in which they dwell. Then the ocean floor is covered with the remains of tiny animals incomparably more numerous than the stars of the sky; and this grey slimy ooze of organic matter hardens by pressure into sedimentary rock. In the course of ages, when the slow decline of the water lays it bare, it may become part of the land on which men dwell. But it is always forming, has always been forming, since life first appeared on the earth. It is on this ocean floor that man to-day lays his telegraph cables. Mr. Rudyard Kipling, in his verses "The Deep Sea Cables," has drawn a vivid picture of the bed of the deep ocean:-- The wrecks dissolve above us: their dust drops down from afar-- Down to the dark, to the utter dark where the blind white sea-snakes are. There is no sound, no echo of sound, in the deserts of the deep, On the great grey level plains of ooze, where the shell-burred cables creep. It is in these silent depths that for uncounted and innumerable years the crust of the earth has been forming and has been growing outwards, while it has been slowly hardening inwards above the fires of its unplumbed interior. It has been calculated that in a square mile of the ocean down to a depth of one hundred fathoms there exist more than sixteen tons of carbonate of lime in the form of the bones or shells of living animals. A continual fine "snow-storm" of dead chalky animals is therefore falling on to the bottom. Here and there, especially among volcanic islands, portions of the sea-bed have been raised up into land and masses of modern limestone. Though these rocks are full of the same kinds of shells as are still living in the neighbouring sea, they have been cemented into hard rock. This cementing is due to the water which has penetrated and permeated the stone, dissolving chalky matter from the outside shells, and depositing it once more lower down and farther in, like a fine mortar, so as to bind the mass together.