CLASSIFICATION OF ROCKS. 69 



positions. Hence the primitive and secondary classes 

 were established : while other geologists attempted to 

 assign their common boundary ; thus rendering this 

 arrangement more useful. Men, believing themselves 

 still wiser, afterwards contrived three classes : making 

 an intermediate one, under the substantive-adjective 

 term Transition^ and contriving to persuade equivalent 

 minds, even to this hour, that it was a strictly natural 

 arrangement. This classification has also been con- 

 nected with a system of cosmogony ; but it is not worth 

 an enquiry which of the two was the origia of the 

 other. But, if less true than the simple one, as a na- 

 tural arrangement, and less useful as an artificial one, 

 I must first enquire of the old division into primitive 

 and secondary. 



Whatever geographical places the primitive rocks 

 may occupy, they are the lowest in geological posi- 

 tion ; or, up to their boundary, are inferior to all other 

 accompanying rocks ; which thus become the second- 

 ary class. It is further stated, that the strata are 

 always elevated at high angles, and that they follow in 

 parallel order, that their nature is chemical, without 

 marks of mechanical origin, and lastly, that they do 

 not contain organic remains. This class, thus deter- 

 mined, is found to comprise certain rocks, under mine- 

 ral characters, generally peculiar, though not con- 

 stant : whence arise serious errors in deciding on the 

 geological connexions from the mineral character : as 

 has been common. 



The secondary class is, of course, the receptacle of 

 all the rest; and is said to-be characterized by prevail- 

 ing low angles of elevation in the strata, by the me- 

 chanical nature of these, and by their containing or- 

 ganic remains ; while their order is said to be parallel 



