MOUNTAIN SLIDES. 279 



'large interstratal area miglit 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 ratlier mountain slides, compared to which the catas- 

 trophe 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 laud-shp 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 

 Eufiberg, which destroyed the little town of Goldau in Switzer- 

 land, and 450 of its people, on the 2d of September, 1806, is 

 ahnost equally celebrated. In lYYl, according to Wessely, the 

 mountain-peak Piz, near Alleghe in the province of Belluno, 

 shpped 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 dam- 

 ming up the waters of the Cordevole, formed a lake about three 

 miles long, and a hundred and fifty feet deep, which stiU sub- 

 sists, though reduced to half its original length by the wearing 

 down of its outlet and the filhng up of its bed by deposits from 

 streams which enter into it.* 



* Wessely, Die Oesterreichischen Alpenldnder und ihre 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 cleariy traceable to that cause. See Bevue 

 des Eaux et Forets for 1869, pp. 183, 205. 



Professor Filopanti gives in the Patria the history of a new lake in Italy, 

 the formation of which dates from 1870. In the month of January of that 

 year, in the mountainous Commune of Plan del Voglio, near the Apennine 

 crest which separates the province of Florence from that of Bologna, occurred 

 a great land-slip on the left of the Savena, bringing down earth, trees and 

 houses, and obstructing the bed of the torrent to the height of 30 metres, and 

 consequently forcing the waters to rise so far in order to surmount the new 

 obstacle. There was thus formed a small lake on the mountain, measuring 30 

 metres in greatest depth, 50 in breadth, and about a kilometre long, running 

 over into the valley by a rapid cascade. The waters of this little lake had the 

 apparent immobility, the limpidity and the beautiful azure color of the large 



