191^.] STEVENSON— THE FORMATION OF COAL BEDS. 497 



as far north as New River of West Virginia on the eastern side of 

 the bituminous region. 



Evidence of marine conditions here and there in the northern 

 half of the basin becomes distinct early in the Beaver. On the 

 southeast outcrop along New River, West Virginia, one finds a 

 silicious limestone, non-fossiliferous, of which traces appear at 

 localities farther west almost to the Kentucky line. Somewhat 

 liigher is the Eagle limestone of I. C. White, black, blocky and, as 

 are also the associated shales, richly fossiliferous. These deposits 

 seem to be unrepresented farther north and to be confined to a narrow 

 area in West Virginia. No trace of limestone or of any marine 

 deposit within the Beaver is known east from, the Allegheny moun- 

 tains ; none has been observed within the first three bituminous 

 basins of ^Maryland, Pennsylvania or West Virginia, unless the 

 Black Flint of the last state belong to the Beaver and not to the 

 Allegheny, — and it is confined to a small area near the Kanawha 

 River ; nor is there any along the northern outcrop in Pennsylvania 

 and Ohio. In northern Mercer county of Pennsylvania, 60 miles 

 south from Lake Erie, one is on the northern limit of the Upper 

 and Lower Mercer limestones of L C. White, which are in the 

 shale mass underlying the Homewood sandstone and are associated 

 frequently with iron ore. 



These deposits are persistent southward along the Ohio-Penn- 

 sylvania boundary for about 40 miles but they rarely extend east- 

 ward from that line to more than 25 miles. The limits of their 

 area are well marked, north, east and south, within Pennsylvania 

 and no trace is found beyond. The upper limestone is of irregular 

 occurrence in Ohio but the lower bed is persistent with, in several 

 counties, its boundaries at east and west thoroughly well defined. 

 It crosses Mahoning, Portage and Summit, but it is wanting in 

 Medina at the west. It is wanting in the panhandle counties of 

 West Virginia and in eastern Ohio to about 40 miles west from the 

 Ohio River. The Lower Mercer is present southward from Port- 

 age and Summit in an irregular strip, 30 to 50 miles wide, to Vinton 

 county and it enters the northwest corner of Scioto at about 20 

 miles north from the Ohio River. The Avestern boundary is reached 



