THE BLOOMINGTON MORAINIC SYSTEM. 241 



lock in places, and the weaker ridges fade out at intervals. In places each 

 of the bulky ridges are double crested and more or less distinctly separable, 

 making- four ridges aside from the two weaker ones. The system may be 

 traced satisfactorily for a distance of about 300 miles from the northern 

 tier of counties in Illinois around to the western tier in Indiana. In northern 

 Illinois this system becomes so closely associated with other systems in a 

 composite belt that further tracing seems impracticable. This northern 

 portion from Peoria County northward overrides or becomes united with 

 the Shelbyville morainic system, so that the latter is no longer traceable. 

 In western Indiana the Bloomington system is overridden by moraines of 

 late Wisconsin date, which have partially concealed its further course. 



DISTRIBUTION. 



The Bloomington morainic system (carrying with it perhaps the Shel- 

 byville system) separates from the composite belt of moraines in northern 

 Kane County and passes in a course slightly south of west across central 

 Dekalb County, occupying a space about 12 or 14 miles in width. Its 

 outer and inner borders are each characterized by a definite ridge. On the 

 borders of Dekalb and Lee counties, in the vicinity of Shabbona and Paw- 

 paw, it becomes narrowed to only 6 miles, owing to a reentrant angle on 

 the outer border. Thus far the weak inner members of the system are 

 undeveloped. Continuing southwestward it expands in northern Bureau 

 County to a width of 18 or 20 miles. This does not include a weak inner 

 member of the system which sets in near Earlville and leads southward 

 along a line several miles east of the inner border of the main ridges, and 

 whose course is discussed below. The ridge along the inner border dies 

 out in eastern Bureau County, so that upon approaching the Illinois River 

 in southern Bureau County only the ridge on the outer border of the sys- 

 tem is maintained in strength. The ridge which dies out in eastern Bureau 

 County apparently finds continuation in a ridge that crosses northern McLean 

 County, as noted below. The bulky ridge passes southward through west- 

 ern Marshall and northeastern Peoria counties and occupies a width of 

 several miles. The portion in northeastern Peoria County is well shown in 

 the Dunlap topographic sheet, where it forms the divide between Kickapoo 

 Creek and smaller tributaries of the Illinois that flow eastward into the 

 river. The Shelbyville moraine emerges from beneath it in eastern Stark 

 mon xxxviii 16 



