M I -i 1 !IN I >>\l.-l II 1.1'- "I Mil < >M I< > \ U.I.I \ 8 



centre ;in<l Bommit Thia ia clearly the view thai ia most reconcilable 

 irith 1 1 1» - present conditions and the record of ancient conditions which 



• down t" ua in 1 1 1 « - physical n rd of 1 1 • « - rocks. 



The biologioal evidei which we may derive from the rocka about the 



Cincinnati axis doea not favor the idea of its having been ;i barrier during 

 any stage of the carboniferous tim>'. from \\\<- base of the Waverlej tothe 

 highest coal-bearing strata. The onlj level where we find evidence of its 

 having been a distinct barrier ia in the time between tin- upper Cincin- 

 nati beda :in>l the base of the Black Shale During thia time, when the 

 upper hundred feet of the Cincinnati aeriea waa depositing, and during the 

 whole of the Niagara and Corniferoua periods, the Cincinnati axis gives 

 u- evidences that it waa a distinct ridge, rising i" or above the surface "t' 

 the aea; but from that time down to the last of our records of the ancient 

 - it appears t" have been always merged in the uniform oceans or 

 mpa of th"--- days. The fossils of the Bubcarboniferoua period do not, 

 tar :i- I have been able \<< examine them, indicate shore-lines along 

 thi- axis. It i- true the} differ on the t\\" Bides of it- central line, but 

 thia difference seema t^ me to indicate the stead} deepening <>f the sea 

 t'r-'iii it- eastward shore-line towards what ia no* the centre of the Mis- 

 sissippi Valley. 



The conclusions which I believe we are forced to accept from the evi- 

 dence the rocka :itTi >r«i may be briefly summed up aa follows 



That the Cincinnati ;i\i- waa about the level of tin- sea during a 

 part of the Hudson River, Medina, and Niagara epochs. 



Ili.it during the subsequent ages, down to and including the carbon- 

 iferous series, thi probably <>t" no importance aa ;i physical or 

 barrier. 

 Ili.it the coal-period swamps, and the seaa into which they from 

 time t" time sank <l"\vn t<> receive their burial in the drifting sands and 

 iuu<l-. extended over the most if not the whole <>f this 



■ i<l\ of tl videncea of a former connection of the eastern and 



K ntuck) affords us some data for estimating the 

 former extension of these deposits in the other parts of the Ohio Will. \ 

 clear that an erosion scarcel) more considerable than that which 

 n place in Kentucky would have sufficed t.. separate the basin "t" 

 the Appalachian region from that of biichuj 



