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66o CHARLES EMERSON PEET 



water body spans, or more than spans, the history of the entire system 

 of moraines of that time represented in Ohio, Indiana, and Ilhnois. 

 In terms of the history of the succession of the Great Lakes, it spans 

 or more than spans, the history of Lakes Maumee, Whittlesey, War- 

 ren, Dana, and part of Iroquois,' and possibly all of the latter, accord- 

 ing to the interpretation of the time of inauguration of Higher Glacial 

 Lake Champlain. In terms of the history of Lake Chicago, it began 

 earlier, and whether it ended earher or later depends on the time the 

 northern outlet of Lake Chicago was opened up by the retreat of the 

 ice. 



TIME DIVISIONS. 



If the beginning of the retreat of the ice from the Brooklyn- Perth 

 Amboy moraine be counted as Champlain time, then the time since 

 the moraine was made may be divided as follows : 



1. Hudson-Champlain. 



2. Higher Glacial Lake Champlain. 



3. " Marine " Champlain. 



4. Present Lake Champlain. 



Possibly the upper part of the levels marked " Marine " Champlain 



may represent another lake named by Upham Lake St. Lawrence, 



and thus make another division. 



Charles Emerson Peet. 



Lewis Institute, 

 Chicago. 



I For an account of the history and relations of these lakes see Leverett, Mono- 

 graph 41, U. S. Geological Survey, pp. 710-75. 



