PAPERS PRESENTED AT GENERAL SESSIONS 67 



readvaiices of the ice front so that at different stages of 

 retreat moraines were built along the margin of the ice 

 during the time that it was temporarily stationary. 

 These moraines, named from the outer to the inner, are 

 now known as the Shelby ville, Cerro Gordo, Champaign, 

 Bloomington, Marseilles. Minooka, Rockdale, Valparaiso, 

 and the Lake Border System. 



Elgin lies just beyond the outer limits of the Val- 

 paraiso moraine. Driving westward from Elgin along 

 the Grant Highway, one crosses two of the outer mo- 

 rainic belts, one of them about three miles west of Elgin, 

 the other about eight miles west. The hummocky char- 

 acter of these belts, their strong undulations, the promis- 

 cuous arrangements of hills and depressions are the pro- 

 duct of unequal glacial deposition at the front of the ice 

 during two of its halting stages. 



The next stage of recession is recorded by the north- 

 west-southeast trending moraine which crosses the Fox 

 Eiver Valley just south of Algonquin. Further recession 

 of the ice took place, during which a great amount of out- 

 wash po'ured forth in the Crystal Lake and Dundee locali- 

 ties, but the moraines built when this high outwash was 

 laid down were later overridden by the ice which made the 

 Valparaiso moraine, thus adding to the complexity of 

 the morainic topography of the Valparaiso system. 



THE LAKES OF NORTHEASTEBX ILLINOIS 



It is a familiar fact that the great majority of glacial 

 lakes of Illinois are situated in the northeastern part of 

 the State, lying chiefly in Lake County, giving that county 

 its name. This territory is genetically a part of the 

 beautiful lake country of Wisconsin, and its origin in- 

 volves a consideration of most unusual conditions. 



Such picturesque bodies of water as Fox Lake, Grass 

 Lake and Pistakee Lake date back in their history to the 

 formation of the glacial moraines of the Valparaiso sys- 

 tem, when apparently the ice movement was vigorous, the 

 rate of melting of the ice was rapid, and large portions 

 of the ice became detached and buried and entered into 

 the composition of the moraine for a brief time. If this 

 is true, the present topography is not the original topog- 



