400 Foshay — Preglacial Drainage of Western Pennsylvania. 



The elevation of J^o. 6 at the confluence of the Mahoning 

 and Sheuango does not constitute an exception as the well 

 from which the record was taken went 150 feet through drift 

 and not having reached rock was abandoned. There is thus a 

 total fall of 75 feet in the 51*4 miles covered by the table, 

 reaching down to an elevation of only eight feet above the 

 present surface of Lake Erie. 



The fact of a post-glacial elevation of the northern part of 

 the continent is now well established. The differential uplift 

 shown in the younger beaches about the overlapping ends of 

 Lake Erie and Lake Ontario is about two feet per mile.* Mr. 

 McGee's survey of the rise of the older Columbian drift forma- 

 tion would make the Pleistocene and recent deformation 

 amount to about three feet per mile. Adding this dip to the 

 present profile of the floor of Spencer River we obtain an 

 abundant northward fall of the old bed. Well records at 

 Niles, O., show the presence of the old channel at that point. 

 A few miles north of this point the country falls aw T ay towards 

 Lake Erie and a number of country wells give depths of drift 

 filling almost sufficient to prove the fall of the old bed far into 

 Grand River basin. In addition to this the Grand River of 

 Ohio, along with the other Ohio Rivers, was shown by Dr. 

 Newberry's survey to have a buried channel amply deep to be 

 a continuation of Spencer River, f 



The accompanying figure (fig. 1) 

 shows in dotted line the outcrop of the 

 hard Conglomerate Series as drawn on 

 Orton's geological map of Ohio. The 

 remarkable embayment in this out- 

 crop, heading at Youngstown, O., 

 furnishes strong presumptive evi- 

 dence of the existence of a reversed 

 drainage in this locality. The Ma- 

 honing River after coming into the 

 bay at its side and flowing some miles in the normal direction 

 makes a sudden bend and flows at right angles to its former 

 course towards the head of the embayment. The great amount 

 and peculiar form of erosion which the Conglomerate Series 

 has suffered in the formation of this embayment could only 

 have been accomplished by a stream flowing northwardly 

 through the bay in a now deeply buried channel, i. e. Spencer 

 River. 



Even disregarding the northward Pleistocene elevation the 

 only other possible outlet for Spencer River is through the 



*The Iroquois Beach; by J. W. Spencer. Trans. Roy. Soc. Can., 1889, p. 

 128. 

 f G-eology of Ohio, vol. ii, p. 1 99. 



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