FLOODS OF THE ARDECHE. : 257 
from the surface of a basin now almost bared of its once luxu- 
riant woods.* A notice of these floods may therefore not inap- 
propriately be introduced in this place. 
The floods of the Ardeche and other mountain streams are 
attended with greater immediate danger to life and property 
than those of rivers of less rapid flow, because their currents are 
more impetuous, and they rise more suddenly and with less pre- 
vious warning. At the same time, their ravages are contined 
within narrower limits, the waters retire sooner to their accus- 
tomed channel, and the danger is more quickly over, than in 
the case of inundations of larger rivers. The Ardéche drains 
a basin of 600,238 acres, or a little less than nine hundred and 
thirty-eight square miles. Its remotest source is about seventy- 
five miles, in a straight line, from its junction with the Rhone, 
and springs at an elevation of four thousand feet above that 
point. At the lowest stage of the river, the bed of the Chassezac, 
its largest and longest tributary, is in many places completely 
dry on the surface—the water being sufficient only to supply 
the subterranean channels of infiltration—and the Ardeéche it- 
self is almost everywhere fordable, even below the mouth of 
the Chassezac. But in floods, the river has sometimes risen 
more than sixty feet at the Pont d’Arc, a natural arch of two 
hundred feet chord, which spans the stream below its junction 
with all its important affluents. At the height of the inunda- 
tion of 1857, the quantity of water passing this point—after 
deducting thirty per cent. for material transported with the 
eurrent and for irregularity of flow—was estimated at 8,545 
* The original forests in which the basin of the Ardéche was rich have been 
rapidly disappearing for many years, and the terrific violence of the inunda- 
tions which are now laying it waste is ascribed, by the ablest investigators, to 
that cause. In an article inserted in the Annales Forestiéres for 1845, quoted 
by Hohenstein, Der Wald, p. 177, it is said that about one-third of the area 
of the department had already become absolutely barren, in consequence of 
clearing, and that the destruction of the woods was still going on with great 
rapidity. New torrents were constantly forming, and they were estimated to 
have covered more than 70,000 acres of good land, or one-eighth of the sur- 
face of the department, with sand and gravel. 
if 
