2 30 ACTION OF FORESTS ON THE FLOW OF RIVERS. 



regular slops ; it is the bed of dejectiou of an ancient torrent. It 

 sometimes requires long and careful study to detect the primitive 

 form, masked as it is by groves of trees, by cultivated fields, and 

 often by houses, but, when examined closely, and from different 

 points of view, its characteristic figure manifestly appears, and its 

 true history cannot be mistaken. Along the hillock flows a streamlet, 

 issuing from the ravine, and quietly watering the fields. This was 

 originally a torrent, and in the back ground may be discovered its 

 mountain basin. Such extingidshed torrents, if I may use the 

 expression, are numerous." 



The quotation is from Etude sur les Torrents des Haates Alpes, by 

 Surell (Chap, xxiv.), and Mr Marsh adds in a foot-note: — ''In such 

 cases, the clearing of the ground, which, in consequence of a temporary 

 diversion of the waters, or fi'om some other cause, has become re- 

 wooded, sometimes renews the ravages of the torrent. Thus, on 

 the left bank of the Durance, a wooded declivity had been formed by 

 the debris brought down by torrents, which had extinguished them- 

 selves after having swept off much of the superficial strata of the 

 mountain of Morgon. ' All this district was covei'ed with woods, 

 which have now been thinned out and are perishing from day to day ; 

 consequently, the torrents have recommenced their devastations, and 

 if the clearings continue, this declivity, now fertile, will be ruined, 

 like so many others.' " 



And resuming, he goes on to say : — " But for the intervention of 

 man and domestic animals, these latter beneficent revolutions would 

 occur more frequently, and proceed more rapidly. The now scarped 

 mountains, the hillocks of debris, the plains elevated by sand and 

 gravel spread over them, the shores freshly formed by fluviatile 

 deposits, would clothe themselves with shrubs and trees, the intensity 

 of the causes of degradation would be diminished, and nature would 

 thus regain her ancient equilibrium. But these processes, under 

 ordinary circumstances, demand, not years, or generations, but 

 centuries ; and man, who even now finds scarce breathing-room on 

 this vast globe, cannot retire from the Old World to some yet undis- 

 covered continent, and wait for the slow action of such causes to re- 

 place, by a new creation, the Eden he has wasted." 



In a foot-note he adds : — " Where a torrent has not been long in 

 operation, and earth still remains mixed with the rocks and gravel it 

 heaps up at its point of eruption, vegetation soon starts up and 

 prospers, if protected from encroachment. In Provence, ' several 

 communes determined, about ten years ago, to i^eserve the soils thus 



