556 A. F. FOERSTE 



of the bed the clay is replaced by a layer of limestone, 6 to lo 

 inches thick. Both northward in Indiana and southward in 

 Tennessee the Waldron bed maintains its characteristics as a 

 shaly clay farther than the Osgood bed. 



The thickest sections of the Osgood bed are found in central 

 Kentucky. Here the Osgood bed consists almost entirely of 

 soft shaly clay, often 38 feet thick. In southeastern Indiana 

 this clay is represented by the Lower Osgood clay. Along the 

 Ohio River the Lower Osgood clay horizon usually consists of 

 soft shaly clay, locally replaced by a more or less indurated clay 

 rock. Northward the amount of induration increases, especially 

 in the upper half of this horizon. Farther northward, beyond a 

 line connecting Versailles and Vernon, lenses and nodular layers 

 of limestone begin to appear in the upper half of the Lower 

 Osgood clay horizon. Still farther northward, the calcareous 

 element increases at all levels, so that at New Point the equiva- 

 lent of the Lower Osgood clay consists of an inferior quality of 

 limestone. Both the Osgood bed and the lower part of the 

 Laurel bed are quarried here. The Waldron bed may be traced 

 15 miles farther northward, to Milroy, but at Sandusky and at 

 various other localities a considerable quantity of thin limestone 

 is interbedded with the clay. 



At Bledsoe, in northern Tennessee,^ the Osgood bed consists 

 chiefly of soft clay. At South Tunnel most of this clay is more 

 or less indurated. At Baker station the upper half of the bed 

 contains sufificient crinoidal material to form an inferior quality 

 of limestone. Along the Harpeth River the greater part of the 

 Osgood horizon is occupied by more or less calcareous, indurated 

 clay rock, gra.ding into clayey limestone at the top and bottom. 

 Locally, the larger part of the Osgood section may consist of 

 soft clayey limestone. In central and southern Tennessee the 

 Osgood bed consists of rather thin-bedded limestones, weather- 

 ing back more readily than the Laurel bed above and the 

 Clinton bed beneath. Here its identity can often be established 

 only with difficulty. The Waldron bed maintains its character 



^" Silurian and Devonian Limestones of Tennessee and Kentucky," i5«//. GeoL 

 Soc. Am., 1 90 1. 



