LOWER OHIO DRAINAGE SYSTEM. 113 



It, is probable that at the time these deposits were made the Licking crossed 

 the present Ohio at Cincinnati, and, together with the section of the Ohio 

 between Manchester and Cincinnati, continued northward at least to the 

 vicinity of Hamilton, Ohio. Possibly it maintained a northward course, 

 passing Hamilton along the axis of the Great Miami Basin, though it seems 

 quite as probable that it turned southwestward to connect. with the Ohio at 

 the mouth of the Great Miami and passed from there down the Ohio and 

 connected with the Kentuck}^. The drainage, as indicated below, appears 

 to have been along the latter course for a long period before the deposition 

 of the lUinoian drift. 



GRADATION PLAINS BELOW THE LEVEL OF THE TERTIARY DEPOSITS. 



As may be seen by comparing the altitude of these Tertiary deposits 

 on the Lower Ohio and its tributaries with that of the gradation plains of 

 the Middle Ohio or old Kanawha system, the latter are far below the former. 

 It will also be noted that the gradation plains of the Middle Ohio system 

 pertain to valleys which had been cut to a much greater depth than those 

 that carry the Tertiary deposits of the Lower Ohio system. Furthermore, 

 the gradation plains are in a much better state of preservation in the Middle 

 Ohio system than the floor of the valleys which carry the Tertiary deposits 

 of the Lower Ohio system. These features suggest that the gradation plains 

 of the Middle Ohio system and the "intermediate valleys" of the Lower 

 Ohio system are not correlatives and lead us to examine the valleys of the 

 latter system for correlative gradation plains at levels below the Tertiary 

 deposits. 



The glacial deposits have obscured the contours of the Ohio Valley 

 throiighout much of the area between Manchester, Ohio, and Louisville, 

 Ky., rendering it difficult to trace terraces or remnants of gradation plains 

 on the valley borders. They have in a similar manner greatly obscured the 

 northern tributaries of the Ohio. The southern tributaries should, there- 

 fore, afford the best field for the examination of gradation plains. These, 

 however, ha-A^e been examined only to a limited extent by the writer. 

 Observations were carried up the Kentucky only to the mouth of Eagle 

 Creek, about 8 miles, and up the Licking River to Grants Bend, about 12 

 miles. Even less attention was given to other southern tributaries. 



On the Licking River no well-defined remnants of a gradation plain 

 were found below Grants Bend; but for 2 or 3 miles in the vicinity of this 



MON XLI 8 



