150 Review of the New York Geological Reports. 



It is evident from the above passages, that the most recent ob- 

 servations in England now recognize no system between the crys- 

 talline schists or primary stratified, and the true Silurian system. 

 The Taconic rocks must, therefore, be the equivalent either of 

 the lower Silurian, of Wales, or else must be a series wanting in 

 England ; in that case, they may form a new system. 



The rocks which compose the Taconic system are few in num- 

 ber, viz. granular quartz, slate, and limestone, repeated thus in the 

 ascending order : Stockbridge limestone, granular quartz, mag- 

 nesian slate, sparry limestone, Taconic slate. There are, there- 

 fore, two kinds of limestone, and two kinds of slate. 



The most important economical products of this system, are 

 the white and clouded marbles, furnished by the calcareous beds ; 

 the hematitic iron or limonite, derived from the decomposition of 

 the slates and slaty limestones, the white siliceous sand, for glass 

 and sand paper, and for sawing marble ; procured from the gran- 

 ular quartz. 



The absence of trap dykes in this system is remarkable. Prof. 

 Emmons has never yet seen an instance of any description of 

 injected rocks associated with the Taconic beds, and he infers 

 that very few disturbances have occurred since the general uplift 

 of the country. 



New York system. — It is the older palaeozoic rocks, or proto- 

 zoic, of Murchison, that form the characteristic geological features 

 of the State of New York. They occupy all the country lying 

 between lakes Ontario and Erie, and the Pennsylvania line ; also, 

 the greater part of the tract situated south of the primary region j 

 i. e. south of a curved line running along Black river, down the 

 valley of the Mohawk to Johnstown, thence along the meander- 

 ings of the Sacandago river to near Glen's Falls ; thence nearly 

 northeast, to the south end of lake Champlain ; besides a semi- 

 circular belt lying north of the primary region, and between it 

 and the river St. Lawrence and Canadian line ; in all, covering 

 at least two thirds of the entire State. 



Under the name of New York system, Dr. Emmons includes 

 all the oldest fossiliferous rocks, up to the sandstones of the Cats- 

 kill mountains. Mr. Vanuxem includes these in the system, and 

 extends it to the conglomerates of the coal formation. Mr. Hall, 

 on the contrary, excludes from the system, not only the sand- 

 stones of the Catskill mountains, but also the slaty sandstones 



