Correlation of conemaugh formation 161 



prevailing rock throughout the section. A similar condition has heen 

 noted for the Allegheny. 



Underlying the Mahoning and separating it from the Upper Freeport 

 coal bed is a shale, the Uffington. shale of I. C. White. It is not per- 

 sistent, having been removed from wide areas during deposit of the 

 overlying sandstone. Near Morgantown, in northern West Virginia, it 

 is crowded with marine forms which are abundant even at contact with 

 the coal ; elsewhere except in Upshur and Wirt counties the fauna seems 

 to be wanting, but the shales have yielded many plant remains. 



The reappearance of red and green shale much resembling that of the 

 Sbenango beds of the Lower Carboniferous at the top of the Allegheny 

 was noticed on a previous page. In the Conemaugh formation, red shale 

 occurs within the Mahoning interval in Gilmer, Ritchie, Calhoun, and 

 Wood counties of West Virginia, where some wells show a great thickness, 

 the whole interval being filled and the mass being continuous with reds 

 above. A bed 25 feet thick in Wetzel county may belong in its lower part 

 to the Upper Mahoning, and thin streaks referable to this interval are 

 reported in Greene and Washington counties of Pennsylvania. The only 

 occurrence in Ohio is a bed 10 feet in Tuscarawas county resting on the 

 Lower Mahoning, but this may belong to the next interval above, as the 

 Upper Mahoning is not present in Ohio. Practically the reds of the 

 Mahoning are confined to the four central counties in West Virginia. 



Eeds of the interval between Mahoning and the Cambridge limestone 

 are more widely distributed. They are thick and variable in Eitchie and 

 Wood, very thick in Calhoun, less thick in Jackson and Clay, all of them 

 in the central area. These reds are found elsewhere in widely separated 

 localities — Wetzel, Webster, Brooke, and Ohio of West Virginia; Cambria, 

 Indiana, and Westmoreland of Pennsylvania, and occasionally in the 

 Hocking valley of Ohio. The distribution in this interval is certainly 

 much wider than in the Mahoning interval, but away from the central 

 area in West Virginia their occurrence is very irregular and for the most 

 part the beds are very thin; but in the next interval, between the 

 Cambridge and Ames limestones, one finds a great expansion. Imme- 

 diately below the Ames or, if present, the Harlem coal bed is the mass 

 termed by Doctor White the Pittsburg reds, which is so widespread that 

 it deserves to be ranked with the most persistent beds of other types. In 

 the central area — Lewis, Gilmer, Eoane, Eitchie, and Jackson of West 

 Virginia — the Pittsburg reds are very thick and at times continuous with 

 the Washington reds above the Ames limestone, while in several of those 

 counties there are still lower beds within this interval. In Calhoun and 

 Wood counties the Pittsburg reds are less important than in the other 



XIV — Bull. Geol. Soc. Am., Vol. 17. 1905 



