STRATIGRAPHIC SUMMARY. 623 



4. Irondequoit limestone. 



3. Williamstown shale. 



2. Walcott limestone. 



2a. Furnaceville iron ore. 



1. Sodus shale. 



In the Utica region, the Oneida conglomerate, representing Upper 

 Medina, rests upon the Frankfort shales, and is succeeded by 

 Clinton shales and arenites with some limestone beds and iron ores. 

 This eastern Clinton is in part equivalent to the Rochester and 

 Lockport of western New York. 



The Upper Siluric comprises the following subdivisions in the 

 Schoharie region :^* 



5. Manlius limestone. 



4. Rondout water-lime. 



3. Cobleskill limestone. 



2. Brayman shale. 



I. Binnewater sandstone. 



This rests with a hiatus and disconformity upon the Upper 

 Ordovicic (Lorraine). The Cobleskill correlates with the Akron 

 of western New York. In the Helderbergs, the Rosendale water- 

 lime appears below the Cobleskill, correlating approximately with 

 the Brayman. Below it often occurs a second limestone — the 

 Wilbur — this making the lowest marine Siluric stratum of the 

 Helderbergs. Below them generally occur the High Falls or Long- 

 wood shales, and the Shawangunk (Greenpond) conglomerates, 

 both representing early Middle Siluric or Salinan of continental 

 origin. 



In New Jersey and part of Pennsylvania (Delaware valley) the 

 Siluric formations have the following subdivisions : 



SUPERFORMATION. 



Lower Devonic (Coeymans limestone). 

 Upper Siluric or Monroan. 

 Manlius limestone. 

 Rondout formation. 

 Decker Ferry formation. 



" Grabau, A. W., Bull. N. Y. State Mus. Natural History, No. 92. 



