THE VALPARAISO MORAINIC SYSTEM. 345 



SURFACE CONTOURS. 



The Valparaiso morainic system is nearly as complex as the Blooming- 

 ton and Champaign systems, but it does not admit of separation into such 

 distinct ridges. Around the southwestern end of the loop in Dupage and 

 Will counties, Illinois, it is possible to trace three distinct crest lines. Usu- 

 ally, however, there are but two, and in places but a single crest. Where 

 most clearly separable into distinct ridges, there is one ridge which much 

 exceeds the others in bulk, and constitutes the main ridge of the system. 

 Where not clearly separable, the minor ridges either become coalesced with 

 the main ridge or present imperfect ridging. 



In the vicinity of the Wisconsin and Illinois line and thence southward 

 through Lake County, Illinois, the main ridge occupies the eastern part of 

 the system. In the western part the ridging is less definite, though the 

 morainic expression is in places more pronounced than in the eastern part. 

 Upon passing southward across northwestern Cook County a minor ridge 

 makes its appearance on the eastern slope, and is separated from the main 

 ridge by the valley of Salt Creek. This ridge continues across Dupage 

 County. The main ridge covers nearly the entire width of the system in 

 northwestern Cook County, but in Dupage County there is not only the 

 minor ridge on the eastern or inner border, but also one on the western or 

 outer border of the system. The valley of East Dupage River separates 

 the main ridge from the minor ridge west of it. 



From the vicinity of the Des Plaines River eastward to the border of 

 Indiana the three ridges just mentioned are distinctly traceable, the main 

 ridge occupying the central part of the system and the minor ridges the 

 outer and inner borders. The ridge on the outer border is in places sepa- 

 rated from the main ridge by a narrow plain, but is closely associated with 

 it near the State line and also from the Des Plaines River northward. The 

 interval between the main ridge and the minor ridge on the inner border is 

 narrow and generally nearly as undulating as the ridges. Near Matteson, 

 however, a small plane tract separates the two ridges. 



In Lake County, Indiana, the ridge on the north or inner border of 

 the morainic system becomes nearly as prominent as the main ridge, and 

 constitutes the water parting between the Kankakee River system and 

 Lake Michigan. It also constitutes the water parting in a few places west 

 of the State line. 



