[Illustration] [Illustration] _CHAPTER VI._ STRATIFIED ROCKS OF MECHANICAL ORIGIN--FURTHER ILLUSTRATIONS. _Impossible to witness the formation of stratified rocks in the depths of the ocean--On a small scale examples are exhibited by rivers and lakes--Alluvial plains--Their extraordinary fertility--Great basin of the Nile--Experiments of the Royal Society--The Mississippi and the Orinoco--Some rivers fill up their own channels--Case of the river Po--Artificial embankments--Large tract of alluvial soil deposited by the Rhone in the Lake of Geneva--Deltas--The delta of the Ganges and Brahmapootra--Delta of the Nile._ The argument set forth in the last chapter is simple, ingenious, and persuasive. Nay, we must fairly confess that to us it seems conclusive. We do not mean to say that it amounts to a rigorous demonstration. But it affords at least a strong presumption that the process of deposition, the process of consolidation, and the process of stratification, are going on to a vast extent beneath the waters of the ocean; and that, in these latter ages of the world’s history, Aqueous Rocks are slowly growing up under the influence of natural causes, which resemble in every important feature those that are now attracting so much attention within the Crust of the Earth. We are therefore prepared to accept this conclusion, if it be not found at variance with any well-established fact, or with any known and certain truth. But in matters of physical science the evidence of our senses is, after all, the most satisfactory argument. And our readers, no doubt, would like to witness, if possible, with their eyes, the building up of Stratified Rocks. Now, though it is not given to us to see this process in all its colossal magnitude as it goes on within the depths of the mighty ocean, it is yet possible to behold it exhibited, as it were, in miniature, in certain cases where the sediment of rivers is deposited within reach of observation.