36 THE PREGLACIAL DRAINAGE OF OHIO. 



were sunk at Waynesville, but these were at the foot of the hills 

 and only about thirty feet of drift were found. 



From the great width opposite Mt. Holly, the valley con- 

 tracts rapidly to the south. At Waynesville it is only four- 

 tenths of a mile wide, while at Oregonia 6 miles farther down 

 it is less than one-fourth mile in w^idth. The valley continues 

 to contract until a point is reached about three-fourths of a mile 

 south of Ft. Ancient. ,A.t th.is place, locally known as the "Nar- 

 rows", the bluffs of limestone extend directly down to the river, 

 there being scarcely room for the railroad tracks. No rock, 

 other than drift, was observed in the channel at this point, nor 

 could the depth of drift be ascertained. 



Below the "Narrows" the valley widens gradually, but does 

 not become prominent until Morrow is reached. The relations 

 at the "Narrows" indicate the existence of a col at that place. 

 At Morow where the river turns abruptly to the west it receives 

 Todd's Fork, an important tributary from the east, and imme- 

 diatelv below the point of junction there is a marked increase in 

 the width of the valley. This sudden change must be due to 

 Todd's Fork; and the wide valley below the place of junction, 

 to the preglacial work of Todd's Fork and not to the much 

 younger stream, the Little ]\liami. 



From Morrow to South Lebanon the valley continues without 

 noted change ; but just west of the last named place the river, 

 making a sharp bend, flows due south, and immediately the valley 

 begins to narrow. The change is so rapid that just north of 

 Fosters the valley has become a gorge, there being barely room 

 for the railroad on one side of the river and the public road on 

 the other. After retaining this character for a fraction of a mile 

 the valley widens gradually and continues without abrupt change 

 for a number of miles to the south. Another col exists at the 

 narrows immediately north of Fosters. 



Now the question — how shall we interpret the drainage phe- 

 nomena observed from Spring Valley to Fosters? The answer 

 to this is found in the location of the cols and the character of 

 the valleys. From the col at Ft. Ancient a stream flowed north 

 to Spring Valley where it received an important tributary from 

 the west as already described. From the same col probably a 



