GEOLOGICAL CLASSIFICATION 



OF 



ROCKS, 



CHAP. I. 



INTRODUCTORY REMARKS ON THE METHODS OF 

 ARRANGING ROCKS, WHICH HAVE BEEN 

 ADOPTED BY DIFFERENT MINERALOGISTS. 



THE classification of rocks labours under diffi- 

 culties of such a nature, that no system has yet 

 been proposed which can be considered unex- 

 ceptionable ; although the subject has occupied 

 the attention of many geologists of the greatest 

 experience. In the present state of our know- 

 ledge, they seem indeed to be insuperable ; nor 

 does it appear possible to suggest any arrange- 



B 



