OF DENISON UNIVERSITY. 57 



west of the St. Paris channel reveal the fact that the rock floor 

 in this direction is very low and as stated by Dr. Orton, "It is 

 obvious that there are possibilities of broad and deep contin- 

 uous waterways throughout this region."^ This line of evidence 

 would indicate that the preglacial Muskingum drainage found its 

 outlet from the state through Auglaize and Mercer counties 

 into Indiana. Many wells in the latter state give evidence of 

 the continued low level of the rock floor in that direction. 



13. The Southern Tributaries of the Ohio River. 



The rivers which enter the Ohio from the south within the 

 limits under consideration all flow from their mountain sources 

 in a direction corresponding to the general slope of the elevated 

 Cretaceous base level and they seem to have taken those courses 

 in consequence of the slope given by the Tertiary uplift entirely 

 independent of the underlying rock structure. As they ap- 

 proach the Ohio their present channels are deep precipitous 

 gorges cut out of the tableland down to the level of the Ohio 

 river. 



14. Character of the Ohio River Gorge. 



It has been suggested by many wTiters that the gorge of 

 the Ohio in itself presents many characters which would indi- 

 cate its recent age. Its precipitous walls of limestone, shales 

 and sandstones testify to the fact that they have not been ex- 

 posed to the action of disintegrating forces for any great length 

 of time. The overhanging cliffs opposite Portsmouth in the 

 Waverly freestone and shales resemble in no way the old valley 

 forms of the central district. The limestone cliffs around and 

 below Cincinnati on both sides of the river are not especially 

 resisting to disintegrating forces but rather manifest opposite 

 characteristics and yet the upper angles of these cliffs have not 

 rounded to any considerable degree. This portion of the gorge 

 from Cincinnati to the mouth of the Great Miami is postgla- 



'Ohio Geological Survey. Vol. VI, Page 776. 



