276 DEVASTATIONS AND EBSTOEATIONS. 



in the Annales Forestiires for 1843, quoted by Hohenstein, Der WdlA, 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 surface of the 

 department, with sand and gravel." And he goes on to say, — 



" The floods of the Ardfeche 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 previous warning. At the same time, their 

 ravages are confined within narrower limits, the waters retire sooner to their 

 accustomed channel, and the danger is more quickly over, than in the case 

 of inundations of larger rivers. The Ardfeche 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 Chassezao, 

 its largest and longest tributary, ia in many places completely dry on the 

 surface — the water being sufficient only to supply the subterranean channels 

 of infiltration — and the Ardfeche itself 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 inundation of 1857, the quantity of water 

 passing this point — after deducting thirty per cent, for material transported 

 with the current and for irregularity of flow — was estimated at 8,845 cubic 

 yards to the second ; and between twelve o'clock at noon on the 10th of 

 September of that year and ten o'clock the next morning, the water dis- 

 charged through the passage in question amounted to more than 450,000,000 

 cubic yards. This quantity, distributed equally through the basin of the 

 river, would cover its entire area to a depth of more than five inches. 



"The Ardfeche rises so suddenly that, in the inundation of 1846, the 

 women who were washing in the bed of the river had not time to save their 

 linen, and barely escaped with their lives, though they instantly fled upon 

 hearing the roar of the approaching flood. Its waters and those of its 

 Affluents fall almost as rapidly, for in less than twenty-four hours after the 

 rain has ceased in the C^vennes, where it rises, the Ardfeche returns within 

 ■ its ordinary channel, even at its junction with the Rhone. In the flood of 

 1772, the waters at La Beaume de Ruoms, on the Beaume, a tributary of 

 -the Ardfeche, rose thirty-five feet above low water, but the stream was 

 again fordable on the evening of the same day. The inundation of 

 1827 was, in this respect, exceptional, for it continued three days, 

 during which period the Ardfeche poured into the Rhone 1,305,000,000 

 cubic yards of water. 



"The Nile delivers into the sea 101,000 cubic feet or 3,741 cubic yards 

 per second, on an average of the whole year. This is equal to 323,222,400 

 cubic yards per day. In a single day of flood, then, the Ardfeche, a river 

 too insignificant to be known except in the local topography of France, con- 

 tributed to the Rhone once and a half, and for three consecutive days once 

 and one third, as much as the average delivery of the Nile during the same 

 periods, though the basin of the latter river probably contains 1,000,000 



