416 E. O. ULRICH REVISION OF THE PALEOZOIC SYSTEMS 



ing Black Eiver group is represented on both sides, following the upper 

 Chazy on the east and the Pamelia on the west. Minor oscillations with 

 local warping occurred here at various times during the Mohawkian, the 

 formations of the Black Eiver and Trenton groups varying greatly in 

 distribution and character, so as to clearly indicate frequent interruption 

 of sedimentation. The details of the movements are too complex to 

 admit of satisfactory treatment in brief, generalized statements. The 

 sections and tables in figure 10 will help the reader to grasp the situation. 

 Differential movements of the Cincinnati geanticline. — Similar oscil- 

 lations of the flanks of the Cincinnati and Nashville domes occurred. 

 In the former the principal movements consisted of alternate tilting to 

 the north and south. Thus, while the Stones Eiver limestones appar- 

 ently were spread evenly over the whole Cincinnati dome, we know from 

 outcrops along Kentucky Eiver and deep wells to the north of Ohio Eiver 

 that the Lowville limestone is developed chiefly on the south flank. A 

 greater relative depression of this side obtained during the deposition of 

 the Curdsville limestone, which is entirely unknown on the north flank. 

 Complete and seemingly nearly equal submergence of at least the flanks 

 of the dome prevailed during the Hermitage, which is the first of the 

 Trenton formations. Some variation of attitude is indicated during the 

 Wilmore. The apex of the dome was located much nearer Cincinnati 

 than usual, and the Wilmore sea, which laid down nearly 100 feet of 

 limestone in central Kentucky, seems to have failed not only to cover the 

 whole dome, but even to encircle it on the north. Detailed comparisons 

 of sections prove the absence of Wilmore deposits in the vicinity of Cin- 

 cinnati and suggest a small peninsular projection from unsubmerged 

 areas to the north. The succeeding Bigby limestone once more com- 

 pletely encircled the dome ; but the next following Flanagan and Perry- 

 ville limestones are confined to the south flanks, the former covering them 

 rather generally, while the latter was laid down only in narrow embay- 

 ments. The Perryville was succeeded by the Catheys formation, whicli 

 again encircled and possibly completely covered the dome. In this and 

 the preceding stages the northern flanks were more commonly emerged 

 and at no time so deeply submerged as the southern side. In the follow- 

 ing stages, however, the reverse condition predominated. The flrst of 

 the succeeding deposits is the Gratz shale, which is best developed on 

 the northwest margin of the dome along Kentucky Eiver, but is recog- 

 nized in a thinner bed at the mouth of Licking Eiver opposite Cincinnati 

 and somewhat doubtfully at several localities in Ohio and Kentucky 

 from 20 to 30 miles up the Ohio. It seems to be absent entirely on 



