CRUSHING FORCE OF TORRENTS. oe 
turn, bears onwards, and grinds down, at high water, so that its 
current rolls only gravel at its confluence with the Rhone.” * 
Duponchel makes the following remarkable statement: “The 
river Herault rises in a granitic region, but soon reaches calca- 
reous formations, which it traverses for more than sixty kilome- 
tres, rolling through deep and precipitous ravines, into which the 
torrents are constantly discharging enormous masses of pebbles 
belonging to the hardest rocks of the Jurassian period. These 
débris, continually renewed, compose, even below the exit of 
the gorge where the river enters into a regular channel cut in a 
tertiary deposit, broad beaches, prodigious accumulations of 
rolled pebbles, extending several kilométres down the stream, 
but they diminish in size and weight so rapidly that above the 
mouth of the river, which is at a distance of thirty or thirty-five 
kilométres from the gorge, every trace of calcareous matter has 
disappeared from the sands of the bottom, which are exclusive- 
ly silicious.” + 
Similar effects of the rapid flow of water and the concussion 
of stones against each other in river-beds may be observed in 
almost every Alpine gorge which serves as the channel of a 
swift stream. ‘The tremendous cleft through which the well- 
known Via Mala is carried receives, every year, from its own 
erumbling walls and from the Hinter Rhein and its mild tribu- 
taries, enormous quantities of rock, in blocks and boulders. In 
fact, the masses hurled into it in a single flood like those of 
1868 would probably fill it up, at its narrow points, to the 
* At Rinkenberg, on the right bank of the Vorder Rhein, in the flood of 
1868, a block of stone computed to weigh nearly 9,000 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. 
Mémoire sur les Inondations des Riviéres de ? Ardéche, p. 16. ‘‘ 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 attrition that, in the Southern Alps, the atmosphere of 
valleys where the limestone contains bitumen, has, at the time of floods, the 
marked bituminous smell produced by rubbing pieces of such limestone to- 
gether.”—-WESsELY, Die Oecsterreichischen Alpenlinder, i., p. 113. 
t ase pour la création @un sol fertile, p. 20. 
