NATURAL HISTORY. 35 



proportion of our most useful metals, discovers to 

 us an order of animals the lowest in the link, and 

 therefore supposed to have been the first created, 

 and other depositions, which shew that its for- 

 mation has been the result of some previous 

 catastrophe. 



Over the surface of the secondary is found the 

 flcetz, or flat formations. These rocks are of 

 later origin than the two former, and are of very 

 great distribution, laying over each other in stra- 

 tifications, and filling up all spaces between the 

 rocks below and those above them. They are con 

 sidered to be made up of deposits or debris from 

 the other rocks, in combination with organic re- 

 wains formed at different periods, and by different 

 operations of nature through the agency of water. 

 They appear not to have been produced, like 

 the former, by chemical processes; but derive 

 their origin entirely from mechanical depositions. 



In this class of rocks are to be found the fossil 

 remains of the more perfect animals (several at 

 a very considerable elevation above the sea, and 

 others at a great depth from the earth's surface), 

 many of which, from their structure are con- 

 sidered to be antidiluvian ; as some are found 

 in parts of the globe where none of the same 

 species now exist ; and others are of a species 

 which at the present day are altogether extinct. 



These rocks consist of two species of sand 

 stone, two of lime stone, two of gypsum, two of 



D2 



