With the permission of our readers we shall allow Professor Huxley, as far as may be, to tell his own story.[50] As to the ocean floor itself, “It is,” he says, “a prodigious plain--one of the widest and most even plains in the world. If the sea were drained off, you might drive a wagon all the way from Valentia to Trinity Bay. And, except upon one sharp incline about two hundred miles from Valentia, I am not quite sure that it would even be necessary to put the skid on, so gentle are the ascents and descents upon that long route. From Valentia the road would lie down hill for about two hundred miles to the point at which the bottom is now covered by 1700 fathoms of sea-water. Then would come the central plain, more than a thousand miles wide, the inequalities of the surface of which would be hardly perceptible, though the depth of water upon it now varies from 10,000 to 15,000 feet; and there are places in which Mont Blanc might be sunk without showing its peak above water. Beyond this the ascent on the American side commences, and gradually leads for about three hundred miles, to the Newfoundland shore.”
The central plain here described, which has been since found to extend many hundred miles north and south of the cable line, is covered almost everywhere by that soft, mealy sort of mud of which we have already spoken; and this, it is now confidently believed, is nothing else than a stratum of Chalk Rock in an early stage of formation. When thoroughly dried it assumes a whitish color, and exhibits a texture which even to the superficial observer appears closely to resemble fine chalk. Nay, we are told that if so disposed, one may take a bit of it in his fingers and write with it upon a blackboard. Like chalk, too, when chemically analyzed it is found to be almost pure carbonate of lime.
But there is a yet more striking analogy between the mud of the Atlantic and the White Chalk of Europe. Both have been submitted to the magnifying power of the Microscope; and, after an examination conducted with scrupulous care, a wonderful and almost startling identity of mineral, or rather we should say of organic, composition has been established between them. To the naked eye Chalk is simply a soft, earthy sort of stone. But when a thin transparent slice is placed under the Microscope, the general mass is found to be made up of very minute particles, in which are embedded a vast number of other bodies possessing a well-defined form and structure. These are of various sizes, but on a rough average may be said not to exceed a hundredth of an inch in diameter. Hundreds of thousands of them are sometimes contained in a cubic inch of Chalk, together with countless millions of the more minute granules.