BITUMINOUS COAL MEASURES. 245 



Bituminous Coal Measures* 



These differ chiefly from the anthracite coal meas- 

 ure in containing more frequent beds of limestone, 

 marl, clay, and, perhaps, iron ore. 



We cannot present a more intelligible view of the 

 bituminous coal measures of the United States, than 

 by giving the following Section of the Carboniferous 

 System of Ohio, by Lieut. Mather. 



Feet. Fig. 44 _ 



=H Upper coal series. 



|jG Calcareo-silicious rock. 



IF Lower coal series. 



80 ^*^/i;**i:V^35E Conglomerate. 



300; D Waverley sandstone series. 



C Slaty argillaceous rock, con- 

 taining pyrites, &c. 

 B Great limestone deposite. 



" For convenience of description," says Mr. Briggs, 

 I the above strata have been separated into seven 

 groups or subdivisions, which, it is believed, corre- 

 spond with important eras or changes during this 

 deposition." 



I. The first subdivision (marked B) includes the 

 limestone of Adams and Highland counties, and is, 

 probably, merely a continuation of that which forms 

 the rocky strata of the whole western portion of the 

 state. This limestone is of great thickness, and 

 contains, where it has been examined, the petrified 

 exuviae of radiated and molluscous animals of ma- 

 rine origin, some of which belong to extinct genera. 



