CLASSIFICATION OF ROCKS. Jl 



CHAPTER II. 



Enumeration of the Rocks, in tlie order of their superposition, beginning with the oldest. — 

 Also a Tabular View of the New-York System, and of the systems of deposit in the Dis- 

 trict ; and the geographical distribution of the Primary System, and of the division of the 

 New- York System in the district. 



The rocks and groups, as well as other geological products which were observed, have 

 generally been made known in the annual reports of the district. They are as follows, 

 beginning with the oldest or lowest, and ascending upwards, in sequence or succession, being 

 the true order to the mind, though an inverted one to the visible or outward eye, so different 

 is the law of sensation from reflexion. 



Table. 



1. Those of the Primary class, which includes granite, gneiss, hornblende rock, &c. &c. 



2. The products intermediate to the primary and the Potsdam sandstone, the latter being 



the beginning of a series which in New- York extends uninterruptedly to the coal in 

 Pennsylvania inclusive. 



3. Potsdam sandstone. 



4. Calciferous group, consists of the calciferous sandrock and the fucoidal layers of the 



annual reports of the district. 



5. Black river limestone, consists of birdseye limestone, base of the Trenton also, and the 



Chazy limestone of Emmons. 



6. Trenton limestone. 



7. Utica slate. 



8. Hudson river group, consists of the Frankfort slate and sandstone, or rubblestone of 



Eaton, and the sandstone shale or shales of Pulaski. 



9. Gray sandstone of the falls of Salmon river, &c. 



10. Medina sandstone, or redsandstone of Oswego. 



11. Oneida or Shawangunk conglomerate. 



12. Clinton group. , 



13. Niagara group. 



14. Onondaga salt group. 

 16. Water lime group. 



