7P0 A. F. FOERSTE 



and Corryville beds^ of the Cincinnati section. The Utica is 

 absent also in western Tennessee. The Swan Creek limestone is 

 undoubtedly of Lorraine age ; and analogy with the sections in 

 central Tennessee, investigated by Ulrich and Bassler, suggests 

 that the richly fossiliferous beds, containing Platystrophia ly?iXy 

 below the Swan Creek limestone are probably equivalent to the 

 Bellevue beds. No trace of the Fairmount, Bellevue, or Corry- 

 ville beds has been recognized in western Tennessee, in the Ten- 

 nessee River basin. This suggests a more rapid depression of 

 the land eastward, permitting the invasion of the Lorraine sea, 

 while in the Tennessee River basin no deposits belonging to the 

 three horizons named are present. Moreover, the Richmond, 

 although extending further southward and westward, is absent at 

 Swallow Bluff, apparently also at Saltillo, and only a trace of 

 Richmond clay, several inches thick, was found along Horse 

 Creek, at Maddox mill. Again, the Clinton, which has a con- 

 siderable development north, west, and southwest of Nashville, 

 and which presents thick sections even as far south as Centreville 

 and the Swan Creek valley, is less than 4 feet thick at Glenkirk, 

 is 2 feet thick at Swallow Bluff, does not exceed i foot in thick- 

 ness at Clifton, Riverside, and Iron City, is possibly represented 

 by a few inches of decayed ferruginous material at the base of 

 the Silurian section three miles northwest of Waynesboro, and 

 possibly also by the more siliceous base of the Silurian section 

 at the Maddox mill. Finally, the Osgood bed at Riverside is 

 overlaid apparently unconformably by the Laurel, and south of 

 Riverside and Clifton is either represented a much diminished 

 section, not more than 3 feet thick, or cannot be differentiated 

 as a distinct formation. 



The identification of the Warren bed rests chiefly upon the 

 presence of Dhiorthis retrorsa. A variety of this fossil has recently 

 been found in the upper third of the Lower Richmond or Waynes- 

 ville bed, in Indiana, but it has fewer, coarser, and more distant 

 radiating plications than the Warren bed form. However, the 

 identification of a horizon should rest, not upon a single species, 



'John M. Nickles, "Geology of Cincinnati," Journal of Cincinnati Society of 

 Natural History, Vol. XX (1902), No. 2. 



