AGE OS^ CINCINNATI ANTICLINE 419 



In the absence of further evidence, the thinning of the Clinton lime- 

 stone northeastward, toward Lafayette, deserves special consideration. 

 In this connection it should be noticed that the thinning of the Clinton 

 limestone, as above indicated, takes place in a direction very nearly 

 parallel to the trend of the western flank of the anticline. Moreover, 

 the rate of thinning is more rapid between Whites Bend (locality 8) and 

 South Tunnel (locality 4), where the direction is northeast, than between 

 South Tunnel and the localities west of Lafayette (localities 1 and 2), 

 where the direction is more nearly east; in other words, more directly 

 toward the crest of the anticline. From this it is just as easily possible 

 to arrive at the conclusion that the area of non-deposition lay during 

 Clinton times toward the north of South Tunnel and Lafayette, along 

 the Tennessee-Kentucky boundary or northward, as to suppose that the 

 axis of elevation of this Clintonless area coincided with that of the Cin- 

 cinnati anticline, being in fact an early stage in the development of 

 that axis. 



Moreover, the Clinton is known to decrease in thickness on passing 

 from southern Ohio to southern Indiana and adjacent Kentucky ; in 

 fact, it is entirely absent in some of the more western Silurian sections 

 in Indiana, and is less than 3 feet thick in many parts of Indiana and 

 adjacent Kentucky. 



From this it appears fully as likely that an area of shallow waters, 

 with possibly occasional limited land areas, existed in Clinton times in 

 a region distinctly west of the axis of the anticline as that such an eleva- 

 tion existed along the present axis of this fold. 



The thickening of the Osgood clay shale, and, to a less degree, also 

 of the Laurel limestone, along the line from Whites Bend to Lafayette 

 (figures 1 and 3) directly opposes the idea of the early development of 

 a permanent fold along the present trend of the Cincinnati anticline ; 

 especially since the thickening of the Osgood and Laurel beds is more 

 rapid where the direction is eastward, between South Tunnel and La- 

 fayette, than where the direction is more parallel to the trend of the 

 axis, between Whites Bend and South Tunnel. It is scarcely in keep- 

 ing with the idea of the early development of the Cincinnati anticline 

 that these two formations should thicken toward the anticline. 



The Waldron shale is nearly uniform in thickness from the Harpeth 

 River valley northward. The thinning of this formation along Duck 

 river appears to have no relation to the Cincinnati anticline. The for- 

 mation has not been recognized at all in the Tennessee River valley. 



Since the Louisville limestone, in the area investigated, is everywhere 

 overlaid unconfoxmably by Devonian rocks, it is impossible to determine 

 what were its original variations in thickness. 



LX— Bull. Geol. Soc. Am., Vol. 12, 1900 



