“The destruction of the globe by some great catastrophe is a dramatic conception; far more so, certainly, than that of the action of the forces now in operation, though they threaten our planet with a destruction equally certain. Does not the stability of our continent seem permanent? Except through the intervention of some new agency, how is it possible to doubt the durability of this earth which has supported so many generations before our own, and whose monuments, of the greatest antiquity, prove that if they have come down to us in a state of ruin, it is not because the soil has refused to support them, but because they have suffered from the ravages of time and especially from the hand of man? The oldest historical traditions show us rivers flowing in the same beds as today, mountains rising to the same height; and as for the few river-mouths which have become obstructed, the few land-slides which have occurred here and there, their importance is so slight relatively to the enormous extent of the continents, that it seems gratuitous indeed to seek here the omens of a final catastrophe. “Such might be the reasoning of one who casts a superficial and indifferent glance upon the external world. But the conclusions of one accustomed to scrutinize closely the apparently insignificant changes taking place about him would be quite different. At every step, however little skilled in observation, he will discover the traces of a perpetual conflict between the external powers of nature and all which rises above the inflexible level of the ocean, in whose depths reign silence and repose. Here, the sea beats furiously against the shore, which recedes slowly from century to century. Elsewhere, mountain masses have fallen, engulfing in a few moments entire villages and desolating smiling valleys. Or, the tropical rains, assailing the volcanic cones, have furrowed them with deep ravines and undermined their walls, so that at last nothing but ruins of these giants remain. [Illustration: THE SEA AT WORK. ] [Illustration: STREAM EROSION. ] “More silent, but not less efficacious, has been the action of the great rivers, as the Ganges and the Mississippi, whose waters are so heavily laden with solid particles in suspension. Each of these small particles, which trouble the limpidity of their liquid carrier, is a fragment torn from the shores washed by these rivers. Slowly but surely their currents bear to the great reservoir of the sea every atom lost to the soil, and the bars which form their deltas are as nothing compared with what the sea receives and hides away in its abysses. How can any reflecting person, observing this action, and knowing that it has been going on for many centuries, escape the conclusion that the rivers, like the ocean, are indeed preparing the final ruin of the habitable world?