^48 bSVASTATIOirS OOOASIONSD BY TORRfiNfS. 



avalanches is well illustrated by the fact that, where the forest is wanting, 

 the inhabitants of localities exposed to snow-slides often supply the place of 

 the trees by driving stakes through the snow into the ground, and thus 

 checking its propensity to slip. The woods themselves are sometimes thus 

 protected against avalanches originating on slopes above them, and as a 

 further security, small trees are cut down along the upper line of the forest, 

 and laid against the trunks of the larger trees, transversely to the path of the 

 slide, to serve as a fence or dam to the motion of an incipient avalanche, 

 which may by this means be arrested before it acquires a destructive 

 velocity and force. 



" In the volume cited in the text, Reclus informs us that ' the village 

 and the great thermal establishment of Barfeges in the Pyrenees were 

 threatened yearly by avalanches which precipitated themselves from a 

 height of 1,200 metres and at an angle of 35 degrees ; so that the inhabi- 

 tants had been obliged to leave large spaces between the different quarters 

 of the town for the free passage of the descending masses. Attempts have 

 been recently made to prevent these avalanches by means similar to those 

 employed by the Swiss mountaineers. They cut terraces three or four yards 

 in width across the mountain slopes, and support these terraces by a row 

 of iron piles. Wattled fences, with, here and there a wall of stone, shelter 

 the young shoots of trees, which grow up by degrees under the protection 

 of these defences. Until natural trees are ready to arrest the snows, these 

 artificial supports take their place and do their duty very ,well. The only 

 avalanche which swept down the slope in the year 1860, when these works 

 were completed, did not amount to 350- cubic yards, while the masses which 

 fell before this work was undertaken contained from 75,000 to 80,000 cubic 

 yards.' " — La Terre, vol. i. p. 233. 



In many cases such as are cited the evil may be traced to the infiltration 

 of water upon argillaceous beds, such as are referred to, which thus become 

 lubricated, and so admit of the sliding over them of thick beds of super- 

 incumbent earth, bearing with them, it may be, houses, and trees, and cul- 

 tivated fields; in other cases, the infiltrated water comes upon beds of 

 materials the disintegration of which leads to similar results. 



M. Marschand — after describing a deposit on which is situated the village 

 of Meyronnes, and its lands in the upper part of the valley of Barcelonette, 

 in the Lower Alps, which deposit was then in movement in one mass 

 throughout the whole extent, from Saint-Ours to the Ubayette, a distance 

 of about ^\ kilometres, or two miles and a half, threatening direful conse- 

 quences, which he details — -states, that any one may see at a glance from a 

 road on the Sylve, a mountain situated on the other side of the valley, that 

 this movement is manifestly attributable primarily to the waters of a 

 stream, the sources of which are, at Fous-Vive and at Saiut-Ours, being 

 absorbed largely by the ground which it traverses, which is thereby soft- 

 ened, — and secondarily to the percolation of water produced by the melting 

 of the accumulated snow on the southern slope of the mountain of Saint- 

 Ours, — and, in fine, to the meadows covering the ground being extensively 

 irrigated, and an additional percolation of water resulting from this irriga- 

 tion. The cohesion of the mass was being thus destroyed, and the base of 

 the mass was being at the same time undermined by the waters of the 

 Ubayette; and it was hianifest that the catastrophe threatened must 

 happen sooner or later. 



