190 On the Formation tftlie Lake df Mauvoism^ 
these causes the body of the glacier which formed the retain- 
ing wall of the lake, was so much dimini^ed in thickness^ that 
the door of the gallery was reduced from its original length of 
boo to 8 feet. As soon as the cascade had cut through the cone 
of icoj it attacked the debris of the base of Mauvoisin, upon 
whicli the cone rested, and having carried it off by degrees, it be- 
came kble to push the soft soil from the foot of Mount Man- 
-voisin, and excavate for itself a passage between the glacier and 
the rocky beds which compose the mountain. As soon as this hap- 
pened, the water rushed out ; the ice gave way with a tremen-^ 
dous crash ; the lake was emptied in half an hour ; and the sea 
of Welter which it contained precipitated itself into the valley 
with a rapidity and violence which it is impossible to describe. 
The fury of this raging flood was first stayed by the narrow 
gorge below^ the glacier, formed between Mont Pleureur and a 
projecting breast of Mont Mauvoisin. Here it was engulfed 
with such force, that it carried away the bridge of Mauvoisin, 
ninety feet above the Dranse, and even rose several fathoms 
above the advanced mass of the mountain. From this narrow 
gorge, the flood spread itself over a wider part of the valley, 
which again contracted into another gorge ; and in this way^ 
passing from one basin to another, it acquired new violence, 
and carried along with it forests, rocks, houses, barns, and cul- 
tivated land. When it reached Le Chable, one of the principal 
villages of the valley, the flood, which seemed to contain more 
debris than water, was pent up between the piers of a solid 
bridge, nearly fifty feet above the Dranse, and began to attack 
the inclined plain upon which the church and the chief part of 
the village is built. An additional rise of a few feet would have 
instantly undermined the village ; but at this critical moment the 
bridge gave way, and carried with it the houses at its two extre- 
mities. The flood now spread itself over the wide part of the 
valley between Le Chable and St Branchier, undermining, destroy- 
ing and hurrying away the houses, the roads, the richest crops, 
and the finest trees loaded with fruit. Instead of being encum- 
bered with these spoils, the moving chaos received from them 
new force ; and when it entered the narrow valley from St Bran- 
chier to Martigny, it continued its work of destruction till its 
fury became weakened by expanding itself over the great plain 
