All. I.] Clakk, Diainage Modifications. i 3 



several places. The chant^e in character of the valley walls 

 above and below this stretch, as well as the deepening of the 

 rock floor of the valley whichever way one goes from it, leave 

 no doubt that there was at some time a col across it. The 

 position chosen in mapping this col was selected after studying 

 the location of the divide on either side of the stream as indi- 

 cated by lateral drainage. 



As shown on the map, the small pre-glacial valley in which 

 Rocky Fork heads was originally tributary to the North Foik 

 of the Licking. It is to be noted that the glacial deposit at its 

 mouth is too low to have been a factor in the cutting down of 

 the col whose removal has permitted reversal of the drainage 

 in this valley. The old valley floo' at and above this moraine 

 is so nearly level that a ditch no more than ten feet deep lead- 

 ing out toward the North Fork would in time pirate a consider- 

 able portion of the Rocky Fork's head waters. Indeed up to 

 within a very few years this valley floor has been swamp for a 

 distance of one or two miles and entirely unfit for agricultural 

 purposes. All the county maps that I have seen show it a 

 swamp or lake, and it is not yet sufficiently well drained to 

 withstand a wet season. 



Before passing from this part of the subject it would not 

 be out of place to call attention to the eroded col that has been 

 located on the North Fork near the Knox-Licking county line. 

 The work and credit of locating this old col belongs with the 

 unpublished article of Professor Tight to which reference has al- 

 ready been made; but its correlation with the modifications 

 about the head waters of the Old North Fork makes necessary 

 a brief mention of it at least in this connection. It is the 

 easternmost erosion in the East-and-West line of the divide be- 

 tween the Old Mt. Vernon and Old Newark Rivers. 



In tramping about over this section of the state many evi- 

 dences were found of the high water level that must have exis- 

 ted West and North of the great divide before and while its 

 cols were being eroded. In several places glacial debris was 

 found on the tops of cols between minor systems lying entirely 

 within the glaciated region. Such cols being covered by the 



