The control of torrents and torrential summer rains is another 

 important function of the forest cover. After such rains you will 

 see a muddy stream more or less swollen. The muddy color is due 

 to the wash from the fertile farm lands through which the river 

 has come. It represents the best and most soluble part of the soil, 

 and its loss is in every instance a detriment to the farm from which 

 it has come. 



The water in the mountain stream is never muddy, though it may 

 be over a very steep slope. In the forest the bed of leaves arrests 

 the flow of water, covers and protects the soil and holds it in place. 



The torrent and land-slide areas in France and Switzerland have 

 cost those countries many years of painstaking toil and much money 

 to restore the forest cover when it had been carelessly removed ; and 

 we are experiencing much the same results in some parts of the 

 west today. 



This brings us to another important forest influence, namely : the 

 Prevention of erosion. 



Every particle of matter on our hillsides is on its way to the 

 ocean level, so long as the law of gravitation exists. The more 

 soluble the substance, the more rapid its descent to the water level — 

 lost to our productive acres. This means not only a loss to agri- 

 culture, but a loss to water consumers and to navigation as well, for 

 all this material is carried into the rivers from the small streams and 

 brooks by which they are fed. The disastrous results are hastened 

 greatly by exposure to the action of wind and rain. The effects 

 are not limited to China or Asia Minor, but may be plainly seen in 

 many parts of this country today. In fact, the evil effects of soil 

 erosion over denuded areas are everywhere evident. Not only is the 

 best and most fertile soil being carried away from the farms and 

 woodlands on the hills, but the loss to the groundwaters in this 

 surface run-oflf is tremendous. Moreover, the silt and debris fills 

 up the streams and rivers, and they will have to be dredged at great 

 expense, and they will be fouled and polluted and made unfit for 

 drinking purposes. 



There are too many such instances. The problem is a large one — 

 too large to ignore. Older and more experienced nations have 

 learned not only that such evils must be corrected, but have corrected 

 them, though at a cost of millions where thousands would have 

 sufficed if restorative measures had been applied earlier. 



Fertile soil is perhaps the most precious inheritance we have 

 received from the long past. It forms but a small part of the 

 earth upon which we tread. Once removed, or destroyed, it is with 

 great difficulty restored. Without it no crop can be raised. In 

 the eternal round of things it is constantly moving to the ocean 

 level, and is constantly being formed again. The rate of its removal 

 and the rate of its formation are factors which determine whether 



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