GENERAL OBSERVATIONS. 376 



1. Pennsylvania Section. 

 Lower Silurian. 

 Primordial, Potsdam Epoch. — " Primal Series " of Rogers, — sandstones and slates 



3,000-4,000 feet. 

 Canadian, Calciferous Epoch. — " Auroral " calcareous sandstone, 250 feet. 



Quebec and Chazy Epochs. — "Auroral" magnesian limestone, with some 

 cherty beds, 5,400 feet. 

 Trenton, Trenton Epoch. — "Matinal " limestone, with blue shale, 550 feet. 

 Utica Epoch. — " Matinal " bituminous shale, 400 feet. 



Cincinnati Epoch. — " Matinal " blue shale and slate, with some thin gray cal- 

 careous sandstones, 1,200 feet. 



Upper Silurian. 



Niagara, Oneida Epoch. — " Levant Gray " sandstone and conglomerate, 700 feet. 



Medina E^och. — " Levant Red " sandstone and shale, 1,050 feet; and "Le- 

 vant White" sandstone, with olive and green shales, 700 feet: total, 1,810 



feet. 

 Clinton Epoch. — " Surgent Series," shales of various colors, both argillaceous 



and calcareous, with some limestones, ferruginous sandstones, and iron-ore 



beds, 2,600 feet. 

 Niagara Epoch. — Not well defined; possibly corresponds with part of the 



" Surgent " series. 

 Salina, Saliferous Epoch. — "Scalent" variegated marls and shales, some layers of 



argillaceous limestone, 1,650 feet. 

 Lower Helderbekg. — "Scalent" limestone, thin-bedded, with much chert, 350 



feet; " Pre-meridian " encrinal and coralline limestone, 250 feet; total, 600 



feet. 

 Oriskany, Orishany Epoch. — "Meridian" calcareous shales, and calcareous and 



argillaceous sandstone, 520 feet. 



Devonian. 



Corniferous, Cauda-galli Epoch. — M Post-meridian " silico-calcareous shales, 200- 

 300 feet. 

 Corniferous Epoch. — " Post-meridian " massive blue limestone, 80 feet. 

 Hamilton, Marcellus Epoch. — "Cadent" Lower black and ash-colored slate, with 

 some argillaceous limestone, 800 feet. 

 Hamilton Epoch. — "Cadent" argillaceous and calcareous shales and sand- 

 stone, 1,100 feet. 

 Genesee Epoch. — " Cadent " Upper black calcareous slate, 700 feet. 

 Chemung, Portage Epoch. — "Vergent" dark-gray, flaggy sandstones, with some 

 blue shale, 1,700 feet. 

 Chemung Epoch. — Vergent" gray, red, and olive shales, with gray and red 

 sandstones, 3,200 feet. 

 Catskill. — "Ponent" red sandstone and shale, with some conglomerate, 6,000 feet 



Carboniferous. 



Subcarboniferous, Lower. — "Vespertine" coarse, gray sandstones and siliceous 

 conglomerate at the eastward, becoming fine sandstones and shales at the 

 westward, 2,660 feet. 

 Upper. — " Umbral " fine red sandstones and shales, with some limestone, 

 3,000 feet. 

 Carboniferous, Millstone-Grit Epoch. — " Serai " siliceous conglomerate, coarse 

 sandstone and shale, including coal-beds, 1,100 feet. 

 Coal-measures. — 2,000-3,000 feet. 



