XX PREFACE. 



conveniences are far exceeded by that which re- 

 sults from frequent changes ; while such a prac- 

 tice offers a bad example to those who, from a 

 minute ambition, are always too ready to follow 

 in the same path ; or who, from incapacity or 

 indolence, find it easier to remove a difficulty by 

 the invention of a name, than by an attentive 

 study of their specimens, and a comparison with 

 the descriptions of preceding writers. To this 

 it may be added, that whatever convenience may, 

 on the other hand, result from reforming the pre- 

 sent nomenclature of rocks, the state of the 

 science is as yet so imperfect, that it could not at 

 present be effectually done. To make changes 

 therefore, that must in succession be amended by 

 future reformations until the time for a complete 

 and effectual one is arrived, would be to increase 

 the confusion of this subject for a Jong period, 

 aud thus to generate a deeper obscurity than that 

 which results from the present deficient state of 

 the nomenclature. 



The geological reader who is acquainted with 

 some recent attempts on this subject, will find 



