DESTRUCTIVENESS OF MAN. 33 
single thaw, so that the entire precipitation of months is in a 
few hours hurried down the flanks of the mountains, and through 
the ravines that furrow them; the natural inclination of the 
surface promotes the swiftness of the gathering currents of 
diluvial rain and of melting snow, which soon acquire an almost 
irresistible force and power of removal and transportation; the 
soil itself is less compact and tenacious than that of the plains, 
and if the sheltering forest has been destroyed, it is confined by 
few of the threads and ligaments by which nature had bound 
it together, and attached it to the rocky groundwork. Hence 
every considerable shower lays bare its roods of rock, and the 
torrents sent down by the thaws of spring, and by occasional 
heavy discharges of the summer and autumnal rains, are seas 
of mud and rolling stones that sometimes lay waste and bury 
beneath them acres, and even miles, of pasture and field and 
vineyard.* 
Destructiveness of Man. 
Man has too long forgotten that the earth was given to him 
for usufruct alone, not for consumption, still less for profligate 
waste. Nature has provided against the absolute destruction 
of any of her elementary matter, the raw material of her works ; 
the thunderbolt and the tornado, the most convulsive throes of 
even the volcano and the earthquake, being only phenomena of 
decomposition and recomposition. But she has left it within 
* The character of geological formation is an element of very great import- 
ance in determining the amount of erosion produced by running water, and, 
of course, in measuring the consequences of clearing off the forests. The soil 
of the French Alps yields very readily to the force of currents, and the decliv- 
ities of the northern Apennines, as well as of many minor mountain ridges 
in Tuscany and other parts of Italy, are covered with earth which becomes 
itself almost a fluid when saturated with water. Hence the erosion of such 
surfaces is vastly greater than on many other mountains of equal steepness of 
inclination. The traveller who passes over the route between Bologna and 
Florence, and the Perugia and the Siena roads from the latter city to Rome, 
will have many opportunities of observing such localities. 
