54 J. J. STEVENSON — LOWER CARBONIFEROUS, ATPALACHIAN BASIN 



The record of this well was kept with extreme care and the drillings 

 were tested with acid. * Southward the conditions ohserved in Chestnut 

 hill prevail, for at Washington, 12 miles south from Mount Pleasant, the 

 lower shales have disappeared, the upper shales are 95 feet, w-hile the 

 limestones are 27 and 58 feet, dark and light respectivel3\ The same 

 condition exists in Greene county, south from Washington, wdiere the 

 upper shale is 55 feet, 20 feet of it being red rock, while the limestones 

 are 55 feet of dark and 110 feet of white, the latter being the silicious. t 

 This thinning out of the Mauch Chunk across Allegheny and Wash- 

 ington counties is precisely what one should expect in view of the 

 conditions shown by oil-borings within the West Virginia panhandle. 

 Doctor White tells us that in Beaver county of Pennsylvania the thick- 

 ness is not more than one foot; at Wellsburg, in Brooks county of West 

 Virginia, west from McDonalds, the whole Mauch Chunk consists of 

 but 31 feet of shale and sandstone, while at Wheeling, in Ohio count}^ 

 of the same state, the Pottsville and Pocono are in contact. The western 

 limit of the limestone, passing southwest through Washington count}^ 

 of Pennsylvania, crosses the Ohio river not far below Wheeling, for in 

 Marshall count)^ both shale and limestone occur at Moundsville, the 

 reported succession being :J 



Feet. 



Slate and shells 82 



Big limestone 85 



Slate 25 



Northern and western outcrop in Ohio. — Returning to the nortli and 

 passing over into Ohio, one finds difficult}'' in tracing the Shenango 

 shales, for the Pocono becomes shaly in its upper portion and the 

 differentiation between the two divisions has not been carried far beyond 

 the state line. Where the Logan becomes distinctl}^ recognizable in 

 north central Ohio, one finds the conditions as at Wheeling, it and the 

 Pottsville are in contact, so that the Mauch Chunk must be absent ; 

 but in the central part of the state, in Muskingum county, the Max- 

 ville limestone appears somewhat abruptly. It is the equivalent of the 

 upper or fossiliferous limestone of southwestern Pennsylvania. Professor 

 Orton's general section, given in volume vii of the Ohio reports, marks 

 shale as intervening between the Logan and the Maxville. Professor 

 Andrews, in his description of the Maxville, speaks of 12 feet of clay or 

 soapstone between the limestone and the Logan ; but this shale seems 

 to be of very uncertain distribution, for in some localities the limestone 



* I. C. White : West Virginia Geol. Survey, vol. i, 1899, p. 227. 



t J. F. Carll : Annual report Geo!. Survey of Pennsylvania for 1886, pp. G;{C-OGO. 



X I. C. White : West Virginia Geol. Survey, vol. i, pp. ;^63, 300, 307. 



