Part III.] OR POISONED BY VEGETABLE GROWTH ? 
191 
clivities. The soil comes from a great part of all 
the tops, and from all the sides, of all the de¬ 
clivities of all the myriads of valle}^s ramifying 
from all the tributary valleys of the valley of 
the Ganges; and what has passed into the sea 
in the formation of the valley is a mere nothing 
to what has passed down the valley, and does 
now pass down it, from the denudation of these 
infinitely extended surfaces by rain. In the 
rainy season there is, perhaps, a body of surface 
water which flows down the vale to the sea in 
volume fifteen times as great as the spring water ; 
and were every spring of the Ganges permanently 
dried up, the vale would still be flooded every 
year by a stream in volume only less by a fif¬ 
teenth part than that which flows every rainy 
season now, and fourteen times greater than 
that which flows in the three hot months. 
Denudation by rain extends over the whole 
space of the earth. Its pace will be modified, 
hastened, retarded, or partially stopped, by a 
thousand such circumstances as comparative 
hardness of surface, porousness, levelness, vege¬ 
tation, heaviness of rain, &c. &c. Over vast 
tracts denudation by rain is so slow as to be 
quite inappreciable. Still there is, perhaps, 
scarcely any place in nature where excessive, 
