MINERAL OGICAL QUERIES. I23 



5. Do the inclined slaty strata, in the vicinity 

 of Plymouth, belong to the transition class 

 of rocks ? 



Mr Professor Playfair, in his eloquent work, 

 the " Illustrations of the Huttonian Theory," 

 maintains that they are primitive : to me they ap- 

 pear to be transition. 



6. Does the upper part of the mountain of 

 Cader-Idris, in Wales, belong to the newest 

 flcetz-trap formation ? 



My friend, Colonel Fullerton of Bartonholm, 

 shewed me specimens from the summit of Cader- 

 Idris, all of which proved to be porphyry-slate ; 

 hence I infer, that a part, if not the whole, of 

 the summit of this mountain, belongs to the new- 

 est floetz-trap formation. 



7. Are not the mountains in Cumberland prin- 

 cipally composed of transition rocks, partially 

 covered with the newest flcetz-trap forma- 

 tion ? 



Some late- writers consider the rocks of Cum- 

 berland as primitive ; but from the information 

 communicated to me, and the specimens from 

 that county in my possession, I am inclined to 

 refer a considerable portion of them to the transi- 

 tion class. 



8. Is not the porphyry of Cumberland in gene- 

 ral porphyry-slate ? 



