118 GLACIAL FORMATIONS OF ERIE AND OHIO BASINS. 



aims to show that the tributary streams below the mouth of the Great Miami 

 enter through valleys which point up the Ohio Valley. There are, how- 

 ever, streams which are omitted from that map, such as Gunpowder Creek 

 and the North Fork of Big Bone Creek, which point very strongly down 

 the Ohio Valley. It is also found that north from Hamilton tributaries of 

 the Great Miami show a decided tendency to trend down the Miami Valley, 

 not only at their points of entrance but throughout much of their course. 

 This topographic feature, therefore, can scarcely be urged to sustain 

 Fowke's interpretation. 



From Cincinnati down to the mouth of the Great Miami the valley of 

 the present river has scarcely half the width which it presents below the 

 mouth of the Miami. Just below Cincinnati, where the stream is thought 

 to have crossed an old divide (see PI. V), the bluffs reach the exceptional 

 height of about 450 feet, and are very abrupt nearly to the top. Upon 

 passing down the valley they soon assume the worn and receding slopes 

 characteristic of an old valley, though so much smaller than that opened 

 by the Ohio past Hamilton that it seems the natural product of a stream 

 draining only the tract between Cincinnati and the mouth of the Great 

 Miami. If we may judge by the boldness of the bluffs, a prominent col 

 was crossed in the vicinity of the supposed divide. There may, however, 

 have been a narrow notch of considerable depth whose borders have been 

 cut away by the present large stream. 



The old divide crossed by the Ohio above the present mouth of the 

 Licking River has been so greatl}^ filled in by glacial deposits on the Ohio 

 side of the river that its rock contours are much obscured. It is certain, 

 however, that the bluffs are greatly degraded, and it is probable that a very 

 low gap existed here at the time the deflection was produced. 



RELATION OF THE GLACIAL DEPOSITS TO THE EKOSION FEATURES OF THE OHIO 



VALLEY. 



ON THE LOWER OHIO. 



Before attempting to interpret further the changes of drainage which 

 have resulted in forming the present Ohio River, it will be advantageous to 

 consider briefly the relation of the glacial deposits to the erosion features. 

 It so happens that the only part of the immediate valley of the Ohio which 

 has been glaciated lies in the section called the old Lower Ohio, from 



