liANDBLIPS. 243 



hour will end in withdrawing its foundation, and bringing about its total 

 ruin. The prospect is one which it is frightful to contemplate." 



M. Cezanne, in his continuation of the work of Surell, writes, — " There 

 may sometimes be seen, at a certain distance from the hills bordering a 

 torrent, a series of parallel fissures, between which the land appears to be dis- 

 located by unequal landslips. It is not seldom that these landslips extend over 

 a vast surface, and in such a way that the cultivated fields and even detached 

 houses of a higher lying plateau have evidently sunk to a lower level. 



" When, by such fissures, a mountain is thus cut up into prisms unstably 

 balanced, it is enough that some day, on the occurrence of a storm of rain, 

 the gushing waters find their way into a cleft and lubricate the surfaces of 

 these, to occasion a landslip. If the mass of material which crumbles 

 down be considerable, it temporarily bars up the ravine, and soaking itself 

 by degrees with the water it becomes soft ; it then gives way all at once, 

 and precipitates itself in a rush of viscous lava, the impulsive force of which 

 is more formidable than that of pure water, for this lava, not having the 

 fluidity of water, cannot, like it, flow round a resisting object without 

 dragging it along with it, Such appears to be the origin of these dSb&cles 

 of mud, observed by Saussure, and described in his Voyage dans les Alpes, 

 and which he in like manner attributed to the i-upture of a barrage. And 

 it /is only by the supposition of such temporary barrages giving passage to a 

 debdcle, that certain phenomena which accompany torrent floods can be 

 explained and accounted for. 



" A proprietor on the bank of the torrent of Sainte-Marthe states that 

 many a time, while he heard with anxiety, in the silence of the night, the 

 grand roar of the torrent which was eating away his domain, he has 

 remarked distinctly a time of arrest of this — a sudden quieting — which he 

 attributed at once to a sudden cessation of the flood ; but after some 

 minutes the uproar recommenced with greater force than ever ; and anew 

 the tumult of blocks of stone striking against each other gave response to 

 the bellowing roar of the waters." 



M. Scipion Gras relates a case which may be considered characteristic, 

 ■ — " On the ith June 1827 the village of Goncelin, not far from Grenoble, 

 was suddenly threatened by a torrent flood, the inhabitants in alarm ran 

 up on to the embankment; but the waters subsided, the flood seemed to have 

 passed, and, reassured, they retired from the embankment, when, all at 

 once, they saw issue from the gorge a mountain of water which precipitated 

 itself upon them with fury. Forty-two houses were engulfed or over- 

 thrown, twenty-eight people were surprised and drowned ; and half of the 

 village, buried under a layer of mud, of stones, and of rocks, had to be 

 rebuilt on this mass of ruins. How can such phenomena be explained if 

 not by tlie formation and giving way of a temporary natural barrage. 



" The Secheron, a torrent of the Tarentaise, flows between two schistose 

 hills, otherwise firm, but which, since 1853, at which time they were 

 stripped of wood, have been subject to movements which have been 

 rather disquieting. In April 1869 this torrent, stopped by a quantity of 

 earth which had crumbled down, threatened to overwhelm two villages ; 

 the tocsin sounded throughout the valley, assistance was organised, the 

 engineers and the soldiers hastened to the spot, and it required all their 

 exertions to divert the issue of the waters, and prevent the Isfere itself from 

 being stopped in its course." 



