Page:Popular Science Monthly Volume 73.djvu/10

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6
THE POPULAR SCIENCE MONTHLY

strike hands with me in the conviction that the probabilities of the future are at least so great as to render imperative the serious con- sideration of our obligations toward it.

It is a familiar geologic deduction that for long eras rains have fallen on the lands and soils have grown in depth, while the surface has been washed away. Soil-production and soil-removal have run hand in hand, and yet they have been so controlled by the adjustments of nature that no large part of the surface has been swept bare enough to altogether exclude vegetation. More than this, it appears that the usual adjustments of nature make rather for increasing fertility of soil than depletion. It is true that at intervals deformations of the earth have intervened giving mountainous heights and precipitous surfaces from which the soil-product has been washed faster than it could be produced; and desert conditions have also intervened locally; but these diastrophic effects are perhaps rather rejuvenations necessary to the preservation of the continents than destructive episodes. Whenever such heights and slopes have been raised, the atmosphere and its waters have at once begun to grade them down, to cover them with soil, and to give to them a renewed habitability. So, in these and other ways, the gifts of the great past now present themselves to us as the product of a marvelous system of control which has checked excesses and forced movement toward the golden means in which have lain pro- ductivity and congeniality to life. Thus has come our inheritance of a land suitable for habitation, of a soil-mantle of great fertility, of a precipitation conducive to productiveness, and of a system of streams endowed with great possibilities of water-foods, of power and of navigation.

We do not hesitate to enter into the inheritance, but what part shall we take in the regulative system that produced and maintains it? How shall we cooperate with nature in rendering conditions still more serviceable to ourselves, and in transmitting a still greater inheritance for our successors? Clearly we may use the proper revenues of our inheritance, but surely we should not rob our successors of their share in it.

Let us turn at once to the basal factors in the problem, the rain- fall, the soil-formation and soil-wastage, the special theme of this hour. The rainfall may be regarded as an inherited asset, the soil is clearly an inherited asset, even a little soil-removal is an advantage, but reck- less soil-wastage is a serious error. Soils are the product of the atmosphere and its waters modifying the rock surface. When they have aided the air in producing soil by rock decay, the atmospheric waters may pass either into plants or back to the surface through the soil and out by evaporation, or they may pass on down to the ground- waters and thence into the streams, furnishing there the basis for