

THE SURFACE OF THE GLOBE. 35 



ties by innumerable channels ; they collect in their progress some par- 

 ticles, and trace light furrows in their passage. These channels soon 

 unite in the deepest cavities which are indented in the mountain's 

 side ; they glide along the deepened valleys which are formed at the 

 foot, and proceed thus to produce those rivers and streams which re- 

 turn to the sea those waters which had been previously imbibed from 

 it by the atmosphere. At the melting of the snows, or when a storm 

 arises, the mass of these mountainous waters suddenly increases, and 

 precipitates itself with a rapidity proportional to the slope of the de- 

 clivity. Dashing with violence against the foot of those ridges which 

 cover the sides of all the lofty valleys, the torrents carry with them 

 the rounded fragments of which they are composed ; they rub and 

 polish them in their passage ; but in proportion as they arrive in the 

 closer vallies where their fall is lessened, or in large basins where 

 they can spread themselves, they cast on the beach the largest of 

 these stones which they have thus rounded ; the lesser are deposited 

 lower, and nothing reaches the main channel of the river but the 

 smallest particles, or a scarcely perceptible slime. The course of these 

 waters, before they form the larger and lower stream, is often through 

 an extensive and deep lake, in which they deposit their mud, and 

 emerge perfectly pure. But the lower rivers, and all the streams 

 which arise in the lower mountains or hills, also produce, in the soils 

 through which they run, effects more or less analogous to those of the 

 torrents of the lofty mountains. When they are swollen by heavy 

 rains, they assail the foot of the clayey or sandy hills which oppose 

 them in their progress, and carry portions of them into the lower lands 

 which they overflow, and which each inundation thus tends to elevate 

 to a certain extent ; and when these rivers reach the extensive lakes 

 or the sea, and that rapidity which carried with it the particles of mud 

 suddenly ceases, these particles are left at the sides of the mouth ; 

 they finally form lands which extend the coast ; and if it be a coast 

 where the sea also deposits her sand, and contributes to this accumu- 

 lation, it produces in this Way provinces, whole kingdoms ; usually the 

 most fertile, and soon the richest in the world, if their governors will 

 allow industry to use its efforts without interruption. 



Downs. 



The effects of the sea without the co-operation of these inland rivers 

 are less productive. When the coast is flat and the bottom sandy, the 

 waves drive the sand toward the shore ; at each ebb a portion is left 

 dry, and the wind, which generally blows from the sea, casts it higher 

 on the beach. Thus the downs are formed, those sandy hills which, 



