Page:Popular Science Monthly Volume 41.djvu/420

406 by millions of years will be, not the disappearance of the dry land, but that of the sea, which, accompanied by all the fluids, will gradually infiltrate through the crust with which our planet is covered.

The certain feature in M. de L'Apparent's essay is that, before the eternal drought comes on, the terrestrial relief will be leveled. The continental surface will have become an immense plain, in which the Alps, Himalayas, and Andes will be only little hills. The fertility of the soil will be augmented by the considerable formation of vegetable earth, which will at the same time be deprived of sufficient watering by the rarity of rain. Climates, little as we may suppose them to be modified by the decrease of the luminous and calorific energy of the sun, will be entirely transformed. It seems to M. Leotard, in short, that the phenomena contributing to the destruction of the continents will diminish continuously in intensity, while the natural influences tending to result in the desiccation of the surface of the globe will gather energy in the course of ages, preparing for our planet the curious future just described—a future which will, however, be postponed so far that mankind will not be a witness of that end of terrestrial evolution.

Another writer in the Revue Scientifique (H. S.) has called attention to what the land is gaining, believing, in view of the universal stability of affairs, that it must be equal to the losses. The land gains everything, including cosmic dust and meteorites, that falls from space; it gains all the gases that are continually undergoing solidification in flesh and wood, with which they become incorporated; and it gains the shells of all the molluscs, infusoria, etc. With a very insignificant part of what these infinitely small beings have left it has been possible to build cities larger than Paris; and the Great Pyramid may be said to be the work, not of King Cheops, but of the nummulites. If a well-informed person should follow out all the facts bearing on the subject, he would probably find a complete equilibrium, an admirable compensation existing between the gains and the losses of the crust of the earth.

M. de L'Apparent has replied to M. Léotard's criticism that it rests on a misunderstanding which can be easily dissipated. In the summer of 1890, he says, "I discussed, in the Geological Society of France, the general question of erosion, not to predict the actual leveling down of the dry land, but simply to arrive at a method of estimating the duration of the geological periods. My reasoning was as follows: If the present causes of destruction (mechanical and chemical action of running waters and marine erosion) continue to act in the same measure as now, without anything intervening to disturb their working, the continental relief