with Raised Beaches of Lake Erie. 283 



It is a common belief that when the ice-sheet had made its 

 final retreat to the slope north of the continental watershed in 

 Ohio, even though the altitude remained high, lakes would be 

 formed in front of it which would stand at a higher level than 

 the Ft. Wayne outlet, and discharge through passes in the 

 water-shed at altitudes as great as 350 to 400 feet above Lake 

 Erie. Dr. Newberry speaks of these passes as water-gaps and 

 waste weirs.* Prof. E. W. Claypole has indorsed this view 

 and carried the idea further by outlining on a map several 

 theoretical lakes on the north slope of the watershed. f The 

 studies of the past season do not, however, support this map- 

 ping. The actual outline of the ice-margin at that stage in its 

 retreat is far from coincident with Prof. Claypole's theoretical 

 outline. It will be seen from the moraines shown on the 

 accompanying map (fig. 1) that as soon as the ice had with- 

 drawn from the watershed in northern Ohio it had withdrawn 

 so far in northwestern Ohio that there was adequate outlet for 

 the discharge of its waters past Ft. Wayne down to the 

 Wabash river. This outlet being much lower than the passes 

 on the watershed eastward from there, the necessity is re- 

 moved for the existence of extensive lakes at levels sufficiently 

 high to discharge through these passes. It is true that quite 

 heavy deposits of silt occur in the Cuyahoga valley and slight 

 deposits in the valleys which lead to Lake Erie west from that 

 valley, but they are all of earlier date than the latest of the 

 ice advances. While examining the Cuyahoga valley I was 

 accompanied by Prof. Claypole who recognized, with me, as 

 glacial the deposits that cap the silts along the valley. The 

 glacial deposits referred to consist of till along the greater 

 part of the valley, but west of Akron they consist of gravel. 

 The till is aggregated in places into morainic ridges and knolls, 

 and the outer of these ridges has an overwash gravel apron 

 leading from it across the watershed to the Tuscarawas valley, 

 and that too where there are deposits of silt 100-200 feet or 

 more in thickness below both the till and the gravel. This is 

 a clear indication of the presence of land ice in these valleys 

 subsequent to the -deposition of the silts. The probable age 

 and conditions of deposition of these silts constitute a question 

 of much interest, ■ but beyond the scope of this paper, since it 

 does not pertain to the closing stages of glaciation. 



The result of investigation has been therefore to reduce the 

 noteworthy lakes connected witli the closing stages of glacia- 

 tion in Ohio to the one bounded by the beach lines which were 

 recognized by the Ohio Geological Survey. 



* Geol. of Ohio, vol. i, pp. 43-45; vol. ii, pp. 46-48, 51-53. 



fLake Age in Ohio, E. W. Claypole, Trans. Edinb. Geol. Soc, 1887. 



