188 
ANNALS NEW YORK ACADEMY OF SCIENCES 
The abruptness of the valleys and the torrential character of the streams 
as conceived by Fayol appear from his explanation of the origin of the Banc 
de Sainte-Aline, which is about 50 feet below the Grande Couehe and still 
underlies it at a depth of 300 meters. Its content is estimated at 125,000,000 
cubic meters. It appears abruptly and disappears with ecjual abruptness, 
being followed by comparatively fine material and that by the coal. Its 
greatest thickness is at the north and northeast and its fragments prove that 
it was derived from the lower part of the Colombier area. Fayol’s explana¬ 
tion of its origin is 
A fall of part of the mountain occurred in the region of Merlerie; the valley was 
obstructed; the waters accumulated and rose behind this barrier; then, all at once, 
breaking their dam, they carried out the materials as far as to the alluvial plain 
and to the lake. 1 
That a slide as great as this is not impossible is proved by reference to 
some of vast extent in the Alps and elsewhere. But the matter in hand does 
not concern the mass of rock, it has to do only with the mode of transporta¬ 
tion. To the writer, this part of the problem appears much more difficult 
than Fayol seems to think it and the explanation given would only increase 
the difficulty. The valley of the Colombier at this time could not have been 
more than a kilometer wide, for its delta extended only a kilometer into the 
lake and the valley was evidently seven or eight kilometers long. If that 
valley were a kilometer wide, the slidden mass would have to cross it, have a 
length of three kilometers and a height of 40 meters. Such a landslide is 
quite possible in some types of rock, for that in the valley of the Adige near 
Rovereto is greater, and that near Lake Lucerne, mentioned by Fayol, is 
comparable to it. It is not altogether easy to conceive of such a landslide 
in the mica schists of the Colombier region, but certainly it is not impossible. 
A mass so great as this would be an effective dam and the water would 
be ponded behind it. But here one has to consider not a vast river but a 
petty stream, merely a brook, for the Colombier was not much more than 
five miles long and its fall must have been quite rapid, as, for most of the 
length, the brook was in the youthful stage. The pond behind the dam 
could not be much more than a mile long and it would not form at once. 
One has difficulty in understanding how even a cloudburst at the head of 
the brook could gain such impetus as to tear away a mass one kilometer wide 
and three kilometers long. The pond was already there, held back by the 
dam; only the upper part of the slide would be torn away by the flood. The 
normal process would be for the water to cut a channel in the mass, which 
1 Commentry, p. 100. 
