GENERAL OBSERVATIONS. 383 



5. Missouri Section. 

 Lower Silurian. 

 Potsdam, Calci/erous Epoch. — Alternations of crystalline and compact "Mag- 



nesian Limestones," and white or gray pulverulent or firm " Saccha- 



roidal Sandstones," 1300-1500 feet. 

 Trenton, Trenton Epoch. — Bluish-gray and drab compact limestone, with con- 



choidal fracture; buff and gray crystalline limestone, much decomposed 



on exposure ; some blue shale; 435 feet; overlaid by " Receptaculite" 



argillaceous subcrystalline limestone, 130 feet : total, 565 feet. 

 Hudson, Hudson Epoch. — Two beds of blue and gray argillaceous magnesian 



limestone, 60 feet, separated by blue and purple shales, 60 feet: 



total, 120 feet. 



Upper Silurian. 



Niagara, Niagara Epoch. — Compact magnesian and argillaceous limestone, 



150 feet. 

 Lower Helderberg. — Light-gray magnesian limestone, 100 feet. 



Devonian. 



Oriskant. — Light-gray, nearly pure limestone, — thickness not given. 



Corniferous, Upper Helderberg Epoch. — Gray, compact, earthy limestone with 

 chert and some sandstone ; in some parts a hard white oolite, 75 feet. 



Hamilton, Hamilton Epoch. — Blue argillaceous shale, with thin layers of con- 

 cretionary limestone, 50 feet. 

 Genesee Epoch. — Black slate, 6 feet. 



Next follow beds which have been referred by some to the Chemung 

 group, by others to the Subcarboniferous, — viz. : 1st, Light-drab, fine, 

 compact "Lithographic" siliceous limestone, 70 feet; 2d, buff, fine- 

 grained, pulverulent, argillo-calcareous sandstone, with some magne- 

 sian limestone, underlaid by blue or brown argillaceous shale, 100 

 feet ; 3d, fine, compact limestone, overlaid by brown silico-magnesian 

 limestone, 70-120 feet : total, 250-300 feet. 



Carboniferous. 



Subcarboniferous. — 1st, " Encrinital," brown, buff, gray and white, coarse 

 crystalline heavy-bedded limestone, everywhere containing chert, 

 500 feet; 2d, "Archimedes" gray and drab crystalline and compact 

 limestone, with some silico-argillaceous limestones and blue shales, 

 200 feet ; 3d, " St. Louis" hard, crystalline, gray, cherty limestone, 

 with thin beds of argillaceous shale, 250 feet; 4th, "Ferruginous" 

 brown and red, coarse, friable sandstone, in some parts white and 

 " saccharoidal," 200 feet: total, 1150 feet. 



Carboniferous, Coal Measures. — Blue and gray compact limestones, with 

 black, blue, and purple bituminous and calcareous shales, and a few 

 thin beds of coarse sandstone, 250 feet or more. 



