160 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



almost to the Lower Mahoning sandstone. The shale separating the sand- 

 stone plates varies greatly in thickness within the first and second bitu- 

 minous basins of Pennsylvania as well as for almost 20 miles west from 

 Chestnut ridge, in that state, and to this variability are due some of the 

 errors in reports upon that area. 



The Gallitzin coal bed of Franklin Piatt (Mahoning of western Penn- 

 sylvania, not Brush creek of Ohio) is confined to the eastern side of the 

 basin and is in the shales overlying the Lower Mahoning. It may be 

 single, double, or even quadruple. It overlies the Mahoning limestone 

 of I. C. White (not Mahoning limestone of H. D. Eogers), which is 

 divided as is the coal bed, so that the Upper Gallitzin coal may be ac- 

 companied by an Upper Mahoning limestone. The Upper Gallitzin coal 

 bed was mistaken for the Philson of Somerset county by W. G. Piatt in 

 Indiana and Jefferson counties and by Stevenson in the Ligonier valley, 

 for there the shales are so thick that the Upper Gallitzin is as far above 

 the LTpper Freeport as is the Kose (Brush creek) in Somerset. The 

 synonymy is: 



Gallitzin coal bed Speer of Broad Top, Mahoning of western 



Pennsylvania. 



Upper Gallitzin Philson of Indiana and Jefferson counties, 



and Ligonier valley of Fayette and West- 

 moreland counties. 



The Gallitzin beds disappear in western Pennsylvania along with the 

 Upper Mahoning, and the Brush Creek coal bed is let down to the Ma- 

 honing limestone, which in volume v of the Ohio reports is referred to 

 the Brush Creek limestone. This Mahoning limestone is widety distrib- 

 uted either as limestone or calcareous iron ore, but especially along the 

 northern and western sides of the basin. 



The Lower Mahoning sandstone is more persistent than the Upper. 

 It is the Mahoning sandstone of most of the reports on counties west from 

 Chestnut hill in Pennsylvania and is the only member present in Ohio 

 and Kentucky. It is the "Dunkard" sandstone of most of the well 

 records, though the Upper Mahoning appears under the same name in 

 many records from the east side of the basin. 



Along the southeastern outcrop within West Virginia the rocks of the 

 lower Conemaugh become very coarse, and there is an almost continuous 

 mass of more or less conglomerate sandstone from the bottom of the 

 Allegheny, 400 feet being recorded in one well below Charleston. This 

 condition disappears for the Conemaugh as for the Allegheny within a 

 very few miles toward the northwest; but in some localities, far away from 

 the coastline and in the verv middle of the basin, one finds sandstone the 



