MOUNTAIN SLIDES. 287 
interstratal area might occasion a slide that should cover miles 
with its ruins; and similar results might be produced by the 
simple hydrostatic pressure of a column of water, admitted, by 
the removal of the covering of earth, to flow into a crevice 
faster than it could escape through orifices below. 
Earth or rather mountain slides, compared to which the ca- 
tastrophe that buried the Willey family in New Hampshire was 
but a pinch of dust, have often occurred in the Swiss, Italian, 
and French Alps. The land-slip, which overwhelmed, and 
covered to the depth of seventy feet, the town of Plurs in the 
valley of the Maira, on the night of the 4th of September, 1618, 
sparing not a soul of a population of 2,430 inhabitants, is one 
of the most memorable of these catastrophes, and the fall of 
the Rossberg or Rufiberg, which destroyed the little town of 
Goldau in Switzerland, and 450 of its people, on the 2d of 
September, 1806, is almost equally celebrated. In 1771, ac- 
cording to Wessely, the mountain-peak Piz, near Alleghe in 
the province of Belluno, slipped into the bed of the Cordevole, 
a tributary of the Piave, destroying in its fall three hamlets and 
sixty lives. The rubbish filled the valley for a distance of nearly 
two miles, and, by damming up the waters of the Cordevole, 
formed a lake about three miles long, and a hundred and fifty 
feet deep, which still subsists, though reduced to half its origi- 
nal length by the wearing down of its outlet.* 
The important provincial town of Veleia, near Piacenza, 
where many interesting antiquities have been discovered within 
freezing-water was due to compression, not dilatation—and therefore he as- 
cribes to thawing alone effects resulting not less from congelation. 
Various forces combine to produce the stone avalanches of the higher Alps, 
the fall of which is one of the greatest dangers incurred by the adventurous 
explorers of those regions—the direct action of the sun upon the stone, the 
expansion of freezing-water, and the loosening of masses of rock by the thaw- 
ing of the ice which supported them or held them together. 
* WESSELY, Die Oesterreichischen Alpenlinder und thre Forste, pp. 125, 
126. Wessely records several other more or less similar occurrences in the 
Austrian Alps. Some of them, certainly, are not to be ascribed to the removal 
of the woods, but in most cases they are clearly traceable to that cause. 
See Revue des Haux et Foréts for 1869, pp. 182, 205. 
