54 BULLETIN OF THE LABORATORIES 



by other than structural factors. Naturally we turn to the great 

 Scioto lobe of the ice sheet for the explanation. 



Considering now the fact that the whole Muskingum basin 

 was, previous to the ice age, a tributary to this system, or rather 

 that the upper course of the Scioto must be counted as a tribu- 

 tary, for the Muskingum basin is very much larger than the 

 Scioto basin and forms the principal source of water supply, 

 the lower course of the present Scioto, provided it was the out- 

 let of this early drainage, should have a valley of larger size 

 and of corresponding form, width and depth to that of its upper 

 portion ; of form and width because excavated in the same 

 rocks and almost certainly under similar conditions ; of greater 

 depth in order to drain the basin ; of larger size because the val- 

 ley should increase in size towards its mouth. 



At Chillicothe where the Scioto makes a bend to the east 

 it enters the Waverly and Carboniferous hills as a valley about 

 two miles wide with hills rising 300 to 500 feet on each side. 

 This valley grows narrower to the south until at County Bridge 

 it is about one-eighth of a mile wide with high, steep faced 

 rocky hills on each side. In many places the side hills present 

 vertical cliffs. At Higby the valley is again very narrow, and 

 also at Piketon where the Scioto Valley R. R. is cut from the 

 rocky bank next the river and the river is at least for part of its 

 width running on rock bottom. South to the Ohio at Ports- 

 mouth the average width of the Scioto valley is about one half 

 mile, presenting broad and open places where it receives tribu- 

 taries of greater or less size and then narrowing again. Thus 

 making it very evident that there is a great disproportion be- 

 tween the size of the valley and the stream occupying it. Un- 

 like the disproportion referred to in the valley at Frazersburg 

 where the small Wakalomaka creek occupies the old Musking- 

 um valley, here the river is too large for the valley and the evi- 

 dence is all against this being the preglacial outlet of the great 

 interior basin of the Muskingum and Scioto. Here also as in 

 case of the Muskingum and Hocking the general surface of the 



