258 



PLEISTOCENE OF INDIANA AND MICHIGAN. 



eastward from Maple Rapids. Then on its readvance to the Owosso moraine the ice pushed 

 into the newly extended head of the outlet so as to project a tongue 5 or 6 miles westward beyond 

 the even line of curvature which it would otherwise have had. And further, as it readvanced 

 the ice pressed the outlet river up the slope to the south, until it closed the channel again and 

 forced the river back to its course westward from Duplain. Then, while restored flow by this 

 course was going on, the ice built the moraine from Eureka west. Finally, when the ice receded 

 from this moraine, the outlet river rushed again into the narrow passage along the ice front and 

 cut away a considerable part of the north side of the new moraine. The other part of tliis moraine, 



Figuke 1.— Map showing relation of Flint and Owosso moraines to the Grand River channel. 



extending southward from Ithaca into the head of the channel, was not modified in this way, for 

 no river of any size flowed southward between it and the ice. 



This rather complicated history seems clearly indicated by the form and relations of the 

 Owosso moraine in this locality. The particular form of discordance seen in this moraine is 

 precisely of that character which requires the supposition of an axial trough or depression for the 

 ice to enter in order to produce the tongue — a depression which was obviously not there when 

 the Flint moraine was made. 



Although shore lines exist along the north or back slope of the Owosso moraine, the cutting 

 west of Eureka seems much greater than can be ascribed to waves. For several miles east of 



