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formation of torrents there, (6) the destruction of forests leaves the ground a prey to 

 torrents, (c) the torrents disappear with the recrudescence of vegetation. In numerous 

 cases, torrential actions had become so powerful that it was found necessary to attack the 

 evil by auxiliary means in addition to reforesting, and the works that are now undertaken 

 in France for the purpose of checking torrents consist of (a) reforesting, (6) turfing, and 

 preservation of grassland, (c) dyking the torrent beds. 



The distribution of the planting and grassing, over the torrent basin, is a matter of 

 great importance, requiring careful study ; the best results are often secured by adopting 

 a distribution of a natural character. If done judiciously, the work has the effect of 

 reducing the volume of the flood waters and depriving them of solid material. Where it 

 is necessary to consolidate the banks and beds of ravines till forests have gained a footing, 

 this is done by erecting, across the bed, weirs of masonry, stonework, wickerwork or 

 fascines, according to the nature and importance of the torrent or ravine. These barriers 

 retain the gravel and stone, and break the speed of the water so much that it will take 

 twelve hours to descend from the summit of a mountain to the base where formerly 

 it took but thirty minutes. A weir is usually first erected at the outlet of the torrent 

 gorge, then as soon as it becomes silted up, another is constructed just above the mass of 

 deposit, and so on, till the ultimate feeders are reached. In the latter, the weirs are 

 constructed of live willow stakes and twigs or fascines of osiers, which, by taking root, 

 consolidate permanently the debris, and are found most efficacious. When the work is 

 completed, the torrent beds have become shaped in steps, and the water flows evenly in 

 the centre of the course, in a series of reaches and cascades. The banks are then planted, 

 and in a few years the forests above have progressed sufficiently to completely stifle the 

 torrents ; all that is further required is to preserve the trees and herbage ; it would have 

 resulted in a great saving to have done this from the first. How effectual is the mode of 

 extinction of torrents now adopted may be inferred from the fact cited by Costa de 

 Bastelica, that over the torrent of Sainte-Marthe, which was formerly noted for its 

 violence, and carried away every bridge that had been thrown across it, a simple 

 footbridge two feet above the level of the stream can resist the greatest floods that 

 now occur. 



Torrential action is apparently more powerful in warm countries with sudden heavy 

 rains, than in cold countries where the rain is less intense, if more frequent. In England, 

 the rain is well spread over the year, and the general slope of the country is not very 

 rapid ; consequently grasslands seem almost sufficient to prevent floods and the wasting 

 away of the soil with all its evil consequences. On the contrary, warmer countries such 

 as France, Spain, Italy, Switzerland, and Austria, have invariably suffered through 

 torrential action following extensive denudation. According to Marsh, (*) four-tenths of 

 the area of the Ligurian provinces of Italy have been washed away, or rendered incapable 

 of cultivation in consequence of the felling of the woods. 



*The Earth, as modified by Human Action, p. 256. 



