28 R]fisUMB OF SUBELl'S STUDY 0» 



The expression "enormous blocks of rook" may seem vague; I can be 

 more explicit. Coaz reports that at Eenkenberg, on the right bank of the 

 Vorder Ehein, in the flood of 1868, a block of stone, computed to weigh 

 nearly 9000 cwt., was carried bodily forwards — not rolled — by a torrent a 

 distance of three quarters of a mile. Coaz, Die Hochwasser im 1868, p. 54, 

 cited by Marsh, by whom also is cited the following statement from Die 

 Oesterreichischen Alpenlwnder und ihre Forste, by Joseph Wessley, a work 

 published in Vienna in 1853 : — " The terrific roar, the thunder of the raging 

 torrents, proceeds principally from the stones which are rolled along in the 

 bed of the stream. This movement is attended with such powerful attri- 

 tion that, in the Southern Alps, the atmosphere of valleys where the lime- 

 stone contains bitumen has, at the time of floods, the marked bituminous 

 smell produced by rubbing pieces of such limestone together." 



Occasionally it happens that after a temporary suspension of the flow, the 

 torrent of water, and mud, and stones, burst forth afresh. These explosive 

 gushes of mud and rock appear to be occasioned by the caving-in of large 

 masses of earth from the banks of the torrents, which dam up the stream, 

 and check its flow until it has acquired volume enough to burst the barrier, 

 and carry all before it. In 1827, such a sudden irruption of a torrent, after 

 the current had appeared to have ceased, swept off forty-two houses, and 

 drowned twenty-eight persons in the village of Goncelin, near Grenoble, and 

 buried with rubbish a great part of the remainder of the village. 



From these statements it wUl be seen that similar phenomena have 

 occurred elsewhere ; and we may thus be prepared to follow SureU in his 

 study of the phenomena reported by him. 



" There are," says he, " in these irruptions an action Uke to that of the 

 avalanches. The inhabitants of the district designate them by this term ; 

 it is not a mere figure of speech ; there is in reality an identity of cause, as 

 there is a similitude in the effects. When a great mass of water suddenly 

 pours into the gullet of a hassin de reception, resting on a very steep slope, 

 and confined in a deep gorge, this mass no longer flows in accordance with 

 the peaceful rules of hydrostatics. It rises behind to a great height, rolls 

 over on itself, and thus descends the gorge with tremendous rapidity — ^fcir 

 beyond that of the regular current of water which is flowing before it 

 towards the bottom. It must then overtake in succession aU the points of 

 tliat current ; it absorbs all its waters, which it hurries along with itself, 

 and which it assimilates to its own mass. In this course its volume swells 

 in proportion to the distance traversed, and when it debouches in the valley 

 it arrives charged with the whole mass of water which was contained in the 

 bed of the torrent from its birth to its exit from the gorge. It is in reality 

 the whole mass of the torrent heaped up and concentrated simultaneously in 

 a single wave. This phenomenon is identically that of the avalanche, with 

 only this difference, that the water, fluid in the first case, is in the state of 

 snow in the second. By this explanation may be understood the short 

 duration of certain floods,^for instance, an hour after the catastrophe at the 

 bridge of Chaumateron, mentioned above, the bed was dry as it was before. 



" Another fact, not less singular, is that of the hurricane which precedes 

 the torrent. Let us try also to explain this. All the examples of a hurri- 

 cane which I have been able to collect relate to those floods following 

 storms of rain during the close heats of summer. Let us suppose that in 

 one of those sultry days, so common at this season in this part of the Alps 

 a thunder-shower, storm of rain, or water-spout falls on the 6cw«n de rec^tion '■ 



