52 BULLETIN OF THE LABORATORIES 



the ice sheet was great enough to deflect the drainage to the 

 north into the upper basin of the Ohio and cause the cutting 

 down of the cols illustrated in the article referred to, while the 

 ice itself only invaded a small part of the basin, may we not 

 look for some similar modifications in the middle or Ohio por- 

 tion of this great river system ? 



As the tributaries of the Ohio on the north were more like- 

 ly to be modified by the ice invasion, these will be considered in 

 their order below the col at New Martinsville which, according 

 to Profs. Chamberlin and Leverett formed the preglacial divide 

 between the upper and middle Ohio basins. 



The first large tributary, the Muskingum, as has already 

 been shown certainly did not discharge its waters into the Ohio 

 river at its present location. The sluggish current of Willis 

 Creek, the eastern tributary of the Muskingum is probably due 

 to the filling up of the valley at its mouth. It is probable that 

 the present lower Muskingum was represented in preglacial time 

 by a stream corresponding in the direction of its flow to this 

 creek and was appropriated by the modified glacial and postgla- 

 cial systems. 



9. The Hocking River and its Tributaries. 



The Hocking river has its rise on the southern border por- 

 tion of the great drift plain of the Scioto Valley, but instead of 

 delivering its waters into that system it flows to the southeast 

 and enters the hill country of Fairfield and Hocking counties in 

 a narrow gorge somewhat similar to that of the Licking, and 

 continues to the Ohio in a narrow valley evidently modified by 

 glacial influences. A number of the upper tributaries of 

 the Hocking present the same phenomena of narrow rock 

 gorges where they leave the upper drift plain, which would natur- 

 ally drain into the Scioto system, and break through the high 

 divide to the Ohio river. These must evidently be considered 

 the channels of glacial rivers from the Scioto lobe of the ice 

 sheet. 



