wiluams] THE FINAL NEW YORK REPORTS. 53 



Vanuxem and Mather adopted the following plan: They had a "Pri- 

 mary system," including the Archeau as we consider it to-day ; second, 

 the " Taconic system," including a conglomeration of strata, all supposed 

 by Emmons to lie below the Potsdam sandstone ; third, the " New York 

 system," which included the Champlain division, the Ontario division, 

 the Helderberg division, the Erie division, and the Catskill division or 

 group. Above this, according to Mather, followed the " Coal system," 

 the "Red Sandstone system," the "Trappean system," the "Tertiary 

 system," and the " Quaternary system," but Vanuxem enumerates only 

 the last, the " Quaternary system," the others being wanting in New 

 York State. 



On the other hand, Emmons and Hall recognized the New York 

 system as including the Champlain Ontario, Helderberg, and Erie 

 divisions, but placed the rocks of the Catskill Mountains in a separate 

 system, calling it the " Old Red system." The division line in their 

 scheme between the New York system and the Old Red was at the top 

 of the Chemung group. 



When we inspect the local distribution of the several formations in 

 the "divisions" of the New York system we find like differences of 

 usage on the part of the several geologists. For instauce, the Cham- 

 plain group of Emmons and Hall terminates above in the Oneida Con- 

 glomerate, whereas in the reports of Vanuxem and Mather it termi- 

 nates with the Hudson River group. In the Ontario group Mather 

 includes only the Oneida Conglomerate ; Emmons includes the strata 

 from the Medina to the waterlime; Vanuxem, those from the Oneida to 

 the Niagara; and Hall, those from the Medina to the Niagara, inclusive. 

 The Helderberg division was regarded by Mather, Vanuxem, and Hall 

 as extending from the Onondaga salt group through the Corniferous 

 limestone, while Emmons made it begin with the Pentamerus limestone 

 and carried it to the top of the Helderberg limestone. All four of the 

 geologists in their final reports agree in the limitation of the Erie divi- 

 sion, including the rocks from the Marcellus shales through the Che- 

 mung group. 



Another point maybe mentioned: While individual formations are 

 substantially alike as named by the several reporters, there are fre- 

 quent differences in usage, as in the use of " Loraine shales" by Em- 

 mons for the Hudson River group of the other reports, and of " Cor- 

 niferous limestone" by all the authors but Emmons, who uses "Hel- 

 derberg limestone." Besides these differences we notice that deposits 

 are mentioned in some of the reports which are left out in others, and 

 in some reports the name of the rock is given, while in others the word 

 "group " is attached to a geographical name, as " Niagara limestone" 

 and " Niagara group." 



These differences which appeared in the final reports accentuate 

 the difficulties which the geologists met with in attempting to classify 

 the rock formations according to the methods then in use. The old sys- 



