76 MODERN FOREST ECONOMY. 



two kilometres. It is strongly embanked, surmounted 

 by steep declivities, covered with green oaks of eight or 

 ten years' growth, and with Aleppo pines of different ages. 

 Its bassin de reception, of about 250 hectares, or 113 acres, 

 comprises the whole slope, precipitately inclined, with a 

 general south-west aspect ; it is closed at the top by a 

 deep bed of rock cut into peaks of the most imposing 

 aspect. 



'The geological formation in both is absolutely the 

 same, as are all the other conditions, at all the points 

 which I have examined. In no part is to be seen either 

 spring or appearance of humidity ; no water is seen 

 excepting at the time of the storms or great rains, and 

 this water soon passes away, with the differences which 

 will afterwards be mentioned. At all other times these 

 ravines are of a desolating aridity. 



'In the night of the 2nd and 3rd September 18G4 

 there fell a rather abundant rain over all this portion of 

 the mountain. In the morning the argillaceous grounds 

 of Saint-Phalez were saturated, of which evidence was 

 found by any one attempting to cross them. The ravine 

 of Saint-Phalez, the receptable of the surplus water, had 

 flowed but slightly ; that of the Combe d'Yeuse remained 

 dry. 



' The day of the 4th September was very warm ; a 

 water-spout borne along by a south-west wind struck, on 

 the Luberon. Its passage did not last more than forty 

 minutes ; but scarcely had it come when the torrent of 

 Saint-Phalez became awful. Its maximum deliverance was 

 about two cubic metres. It did not flow more than fifty 

 minutes ; but with an average delivery of half a cubic 

 metre ; it had then passed in all 15,000 metres of water. 

 Its height had been 0'04 m. ; each square metre had 

 received 40 litres, and the 50 hectares of Saint-Phalez 

 20,000 cubic metres. The ground had only retained 5000, 

 which is sufficiently explained by their argillaceous 

 character and their state of saturation the night before. 

 While the torrent of Saint-Phalez flowed, filled from bank 



