624 ALLUVIA. 



exposed to the several causes of waste, and on the 

 nature of the materials. 



Organic remains, both vegetable and animal, 

 are found in the alluvial deposits, and these are 

 frequently interesting, as consisting of the bones 

 of many species of terrestrial animals now extinct. 

 It is scarcely perhaps necessary to remark, that 

 minerals sufficiently permanent in their nature to 

 resist the effects of waste, also occur in them ; 

 among which the diamond and gold are the 

 most remarkable. 



In treating of the consolidated alluvia, or of 

 alluvial rocks, strictly speaking, no notice is here 

 necessary of those very partial deposits, formed 

 by infiltration or otherwise, which are found in 

 many situations, and which are more properly 

 described in works of mineralogy. If a line in- 

 deed has not been strictly drawn between those 

 which seem to claim a place here, and those 

 which belong to mineralogical arrangements, it 



