88 THE CHEMISTRY OF CREATION. 



tration of the amount of effect possible to be 

 thus produced, that it has been calculated that 

 the former of these rivers, in the course of a 

 single year, carries down many millions of tons 

 of mud that is, of disintegrated rock. The 

 sediment thus carried down is spread out upon 

 the bottom of the seas, into which it is dis- 

 charged, there forming a layer of yearly increas- 

 ing thickness. 



The more wild and rugged the scenery of 

 nature, the more certainly and rapidly do 

 these agents, first the chemical forces, and next 

 the mechanical, combine to carry on the work 

 of disintegration, and, if we may so call it, 

 decay. In the gorgeous scenery of the Andes, 

 where rise bare and precipitous hills of por- 

 phyry, pinnacles, and fortresses of rock, more 

 wild and grand than painter yet conceived, and 

 where violent conflicts of the elements are not 

 unfrequent, it may be imagined that this process 

 goes on with unusual rapidity. The following 

 passage from the journal of Mr. Darwin conveys 

 the impression with peculiar force : 



"The rivers which flow in these valleys (of 

 the Cordilleras) ought rather to be called moun- 

 tain torrents. Their inclination is very great, 

 and their water the colour of mud. The roar 

 which the Maypu made, as it rushed over the 

 great rounded fragments, was like that of the 



