102 THE ALLEGHANY COAL FIELD. 



stratum, and this is traced up the valley of the Mononga- 

 hela to Brownsville. 



Mr. Briggs, of the Virginia Survey, made a section of the 

 rocks below this bed at Morgantown, to the base of the 

 coal, the conglomerate of Laurel Hill. By comparing it, 

 as given below, with the sections of the coal rocks in Ohio, 

 opposite Wheeling, and below the same bed, to the con- 

 glomerate of the Western Reserve, the thickness of the 

 mass, the number of coal seams, and the number of beds 

 of limestone is entirely difterent. 



This can only arise from a lack of persistence in the 

 strata. In Ohio, the next prominent group of limestone 

 strata, below the Wheeling mass, as it appears on the 

 Muskingum, is called by Dr. Hildreth the " fossiliferous 

 limestone." It crosses the Muskingum in Morgan county, 

 just above McConnellsville. This has been traced nearly 

 to the Ohio River, in Meigs county, and is beneath the 

 Pomeroy coal seam. 



Farther North, in Carroll and Columbiana counties, and 

 in Pennsylvania, it has not been noticed — not so much, 

 perhaps, because it does not exist, as because it has dwin- 

 dled down to a thickness not distinguishable from the 

 ordinary limestone beds of the coal series. 



In Ohio, the silicious bed called Buhr Stone is very 

 marked, and has been traced from the neighborhood of the 

 river, in Gallia county. Northerly into Tuscarawas. A 

 " Buhr," or black flint bed, is described by Prof. Rogers, in 

 his sections on the Alleghanj^ River, and by Mr. Briggs in 

 his sections on the Kanhawa. Probably this siliceous 

 stratum, or its equivalent, will be found to encircle the 

 whole coal field; but at the points where it is cut by our 

 present sections, the number and character of the beds 

 just below it are by no means uniform. 



Again, the sandstone mass, below the Pittsburgh seam, 

 although it is recognizable where it crosses the Ohio, near 

 Steubenville, and the Muskingum, below McConnellsville, 

 is not recognized below the Pomeroy coal seam, where it 



