DRAINAGE. 115 



great chasm appear beds of clay and sand, red, white, yellow, 

 and green, produced by the decomposition in situ of hornbl en- 

 die gneiss with layers and veins of quartz, which remains en- 

 tire to prove that the whole mass was once crystalline." 



Marsh, in his book on " The Earth as Modified 

 by Human Action," * in referring to the effects 

 produced on the drainage of the land by the de- 

 struction of the forest, on page 254, gives the fol- 

 lowing quotation from a paper read by Blanqui, 

 read before the Academy of Moral and Political 

 Science in 1843, concerning the Alps of Provence : 



" The Alps of Provence present a terrible aspect. In the 

 more equable climate of Northern France, one can form no 

 conception of those parched mountain gorges where not even 

 a bush can be found to shelter a bird, where, at most, the wan- 

 derer sees in summer here and there a withered lavender, 

 where all the springs are dried up, and where a dead silence, 

 hardly broken by even the hum of an insect, prevails. But if 

 a storm bursts forth, masses of water suddenly shoot from the 

 mountain heights into the shattered gulfs, waste without irri- 

 gating, deluge without refreshing the soil they overflow in 

 their swift descent, and leave it even more seared than it was 

 from want of moisture. Man at last retires from the fearful 



* Eeprinted, by permission, from " The Earth as Modified 

 by Human Action," by George P. Marsh. New York : Scrib- 

 ner, Armstrong & Co., No. 654 Broadway, 1874. Pp. 656. 



