Oright, of Carbonaceous Shales. 367 



Iron is almost omnipreseut, under such circumstances usually 

 in the form of carbonate; and the formation of concretions of 

 carbonate of lime and pyrites would naturally follow the min- 

 gling of decaying organic matter with sulphate of lime and 

 carbonate of iron. 



The decomposition of the pyrites, so abundant in bituminous 

 shales, seems to be the chief source of the chemical action 

 which results in the formation of the mineral springs that issue 

 from these shales in so many localities. The outcrops of the 

 Utica and Hamilton black shales are marked by the emission of 

 sulphur waters, as they are by gas-springs and oil-springs, in 

 New York, Pennsylvania, Ohio, Kentucky, etc.; and it is also 

 true that the great black shales of the Colorado group in the 

 Far West exhibit the same phenomena. Carburetted hydrogen, 

 carbonic acid and sulphuretted hydrogen, are particularly notice- 

 able, as the gaseous emanations from such sources. The solid 

 jDrecipitates include chloride of sodium and various salts of lime, 

 iron, magnesia, etc. 



Among the published papers which have reference to the 

 origin of cannel coals and bituminous shales, the following may 

 be consulted : — 



On the Formation of Cannel Coal ; J. S. Newberry, Amer. 

 Jour. Sci., Vol. XXIII (1857), p. 212. 



The Eock Oils of Ohio ; J. S. Newberry, Ohio Agric. Report, 

 for 1859. 



On the Chemical and Geological History of Bituminous 

 Shales; Dr. T. S. Hunt, Amer. Jour. Sci., Vol. XXXV (1863), 

 p. 157. 



The Black Shale; Prof. J. M. Safford, Geol. of Tennessee, 

 1869, p. 329. 



The Huron Shale ; J. S. Newberry, Geol. Survey of Ohio, 

 Vol. I, 1863, pp. 107 to 158; Vol. Ill, 1878, p. 13, etc. 



A Source of the Bituminous Matter in the Devonian and Sub- 

 Carboniferous Black Shales of Ohio ; Prof. E. Orton, Amer, 

 Jour. Sci., Vol. XXIV (1882), p. 171. 



