72 THE ILLINOIS GLACIAL LOBE. 



Another belt a few miles to the west runs nearly parallel to the river from 

 Tower Hill, in Shelby County, southwestward to Belleville, in St. Clair 

 County. Still farther west there is a system, less definitely developed, 

 leading from northern Montgomery County southward into northeastern 

 Madison County. South from Belleville the ridges are reduced to a single 

 chain which follows the west border of the Kaskaskia from Lementon, in 

 St. Clair County, southward across eastern Monroe into northern Randolph 

 County. The ridge there crosses to the east side of the river and passes 

 southeastward near Sparta to Steelville. There is a slight ridging as far 

 southeast as central Jackson County, beyond which the drift appears not to 

 be definitely ridged. There are, however, occasional low ridges and swells 

 in the vicinity of the glacial boundary in Williamson, Saline, and Gallatin 

 counties, which may mark the continuation of the belt. 



Of the three systems developed northeast of Belleville the middle one 

 is the best defined and most nearly continuous. It is interrupted only by 

 a few narrow gaps, usually less than 2 miles in width, throughout the entire 

 distance from Tower Hill to Belleville, nearly 100 miles. There are places, 

 as in northeastern Montgomery and in southeastern Madison County, where 

 a continuous ridge is maintained for a distance of at least 15 miles. The 

 belt bordering the Kaskaskia River is maintained for several miles as a 

 continuous ridge in the vicinity of Vandalia, but elsewhere is represented 

 only by fragmentary ridges, seldom more than 3 miles in length, between 

 which there may be gaps of even greater length. The western of the three 

 belts is even more fragmentary, and is maintained for only 20 or 25 miles. 



These ridges are usually rather shai'j) and narrow, but in places assume 

 a billowy topography. In still other places they have a vague irregularity 

 of form and arrangement. The more sharply ridged type, however, pre- 

 vails over the others, and may be said to characterize the system. The 

 sharpest ridge noted is that in the vicinity of Cool Spring post-office, in 

 Shelby County, where a ridge scarcely a mile in width has a height of 130 

 feet. A long ridge leading from Pocahontas, in Bond County, westward 

 into Madison County, and thence southward to the village of Highland, is 

 about 50 feet in average height and scarcely a half mile in average width. 

 Knolls 75 or 100 feet in height are not rare, and occur in nearly every 

 county traversed by this system of ridges. These knolls, as well as the 



