254 THE ILLINOIS GLACIAL LOBE. 



altitude, however, occupies a space of 1 to 2 miles or more, and hence is 

 not conspicuous. The slopes usually present more undulations than the 

 crest, but their swells seldom exceed 20 feet in height. 



The combined belt east from Padua differs from the separate belts 

 farther west in presenting greater complexity of features. Between Padua 

 and Arrow-smith the trend of the principal ridges is northwest to southeast. 

 One ridge with this trend passes immediately west of Ellsworth and consti- 

 tutes the divide between Sangamon River and Kickapoo Creek. Another 

 ridge leads into Arrowsmith from the northwest, which separates the Sanga- 

 mon from the Mackinaw. From the vicinity of Arrowsmith eastward to 

 the reentrant angle in Ford County the trend of ridges is southwest to 

 northeast, or nearly at right angles with those west of Arrowsmith. The 

 ridges just mentioned are low, with a relief of but 30 or 40 feet. There is 

 a prominent crest along the south border of the combined belt which is 

 interrupted by a small gap at the Sangamon Valley. It stands about 100 

 feet above the plain outside the moraine, and rises from that plain with the 

 abruptness of a bluff line. The Sangamon River winds about through sags 

 among ridges until it emerges from this morainic belt. Aside from the 

 ridges and broad sags the moraine is characterized by a multitude of gentle 

 swells 10 or. 15 feet in height, among which there are shallow sags and 

 occasional basins. 



The reentrant in Ford County. — In the reentrant angle in Ford county the ridges 

 on the west are crowded together in a single belt, but those on the east 

 are in part separated by narrow strips of level marshy land which trend 

 with the belt from north-northwest to south-southeast. The topography 

 of the greater part of the reentrant portion is of a gentle swell-and-sag 

 type, with undulations of only 15 or 20 feet. The ridges have definite 

 crest lines standing about 50 feet above the marshy plains which separate 

 them. In southeastern Livingston County, however, at the extreme north 

 end of the reentrant, a sharp knob-and-basin topography is developed, in 

 which knolls rise abruptly 30 or 40 feet above the basins inclosed among 

 them. There are several small lakes and ponds among the morainic knolls, 

 the largest of which occupy areas of 40 acres or more, but the majority 

 occupy only a few acres each. From this point of the reentrant angle 

 there is more or less knob-and-basin topography developed along the inner 

 or northeastern slope of the moraine throughout its southeastward course 



