XXXIV 



INTRODUCTION, 



on the subject is indispensable to a complete treatise on pe- 

 traloey, which should enable the student not only to know 

 the substance, but the denominations used by former mine- 

 Studies ralogists and travellers, and by historians, philosophers, and 

 requisite. p 0e t s ^ which will not only enlarge his ideas but give him 

 more accurate knowledge. And as few of the sciences can 

 be founded on personal observations, vita brevis, ars longa, 

 and the brevity of human life will not permit a petralogist to 

 pass forty years in the Alps with Saussure, thirty in Saxony 

 with Werner, &c. &c. he will of course acquire infinitely more 

 knowledge by the study of their works, than by any personal 

 observations 5 so that this science, like all others, results 

 from accumulated knowledge. 



These observations shall be concluded with Werner's ar- 

 rangement of the rocks. 



Primitive Rocks. 



8 Porphyry. 



9 Sienite. 



10 Topaz Rock.* 



11 Quartz Rock. 



12 Primitive Flinty Slate. 



13 Primitive Gypsum. 



14 White-Stone. 



Werner's 

 rocks. 



CLASS I. 



1 Granite. 



2 Gneiss. 



3 Mica Slate. 



4 Clay Slate. 



5 Primitive Limestone. 



6 Primitive Trap. 



7 Serpentine. 



CLASS II. 



1 Transitive Limestone. 



2 Transitive Trap. 



3 Grey Wacke. 



Transitive Rocks. 



4 Transitive Flinty Slate. 



5 Transitive Gypsum. 



CLASS III. Floetz or Stratiform Rocks. 



1 Old Red Sandstone, or 



first Sandstone Forma- 

 tion. 



2 First, or oldest Floetz 



Limestone. 



3 First, or oldest Floetz 



Gypsum. 



4 Second, or variegated 



Sandstone Formation. 



5 Second Floetz Gypsum. 



