342 Howard Clark 



Evidently the Rocky Fork, in parts B and C, shows reversal; 

 six miles of the valley that formerly carried a westward flowing- 

 stream now carries a stream flowing in the opposite direction. 

 What caused this reversal? 



The drift barrier. Just east of St. Louisville, at the junction 

 of part C with the Licking, is a heavy deposit of glacial drift which 

 forms a barrier across the mouth of the former valley; this 

 moraine barrier has about the same altitude as the valley walls 

 which bear a veneer of till. The barrier presents a steep and 

 irregular front to the south, (fig. 3, A) the ice-contact side, 



Fig. 2. Looking westward across the outwash plain east of St. Louisville. 

 The drift barrier forms the sky-line. 



while its northern front blends into an outwash plain which 

 slopes gently and very regularly into the valley (fig. 2). 



Along the south front of the barrier, about midwa}^ between 

 the rock walls on either side and eighty feet below the highest 

 elevation of the drift, is a well seventy feet deep, entirely in 

 glacial drift. Other well records were obtained, but none were 

 deep enough to establish the maximum thickness of the barrier. 

 As seen in exposures, the drift is made up of gravel, sand and 

 boulders of all sizes imbedded in a matrix of yellow clay; occa- 

 sionally a large granite boulder is seen, two or three feet in 



