COMPOSITE MORAINIC BELT OF NORTHERN ILLINOIS. 291 



Marengo, which is situated in the line of the ridge, but which stands in the 

 North Kishwaukee Valley. It is the only town in Illinois in the direct line 

 of the ridge, though Harvard in Mctlenry County and Hampshire in Kane 

 County are situated near the foot of the outer slope. 



From the State line the course of the ridge is nearly due south to 

 Marengo, from which point it bears southeast to the south line of McHenry 

 County. It then resumes a southward course and continues for about 18 

 miles to the vicinity of Elburn, in Kane County, where it becomes united 

 with the portion of the composite belt to the east. It will be observed that 

 it passes by the eastern end of the outer Bloomington ridge near Hamp- 

 shire. The ridge throughout the greater part of its course has a width, 

 including slopes, of 3 or 4 miles. 



The relief of the outer border is seldom less than 1 00 feet, and in places 

 it reaches 150 feet or more. The inner border has a relief of 75 to 120 feet, 

 but the relief appears less bold than on the outer border, because the ascent 

 to the crest is more gradual. This ridge is closely associated with the 

 remainder of the belt for a few miles south from the State line, and differs 

 but little in altitude from the district on the east. Similarly at the south, 

 where it connects with the remainder of the belt, it has about as great an 

 altitude. 



SURFACE CONTOURS. 



From the State line southward to Hampshire this ridge presents a char- 

 acteristic knob-and-basin topography, so well developed in the Wisconsin 

 Kettle moraine and described by Chamberlin as being "of an exceedingly 

 irregular, intricate character, formed by knobs, peaks, short irregular hills and 

 spurs associated in complex order, interspersed with hollows and depressions 

 of like irregular character, often without outlet." 1 The larger knobs rise 

 scarcely 50 feet above the neighboring basins, and the average height of 

 the knobs is probably not more than 25 feet. They are found both on the 

 crest of the ridge and on the slopes. Aside from the well-defined basins, 

 there are shallow, saucer-like depressions found frequently on the top of the 

 knolls and the slopes of knolls and ridges, as well as in the sags between 

 them. There is a marked distinction between the contours of the prairie 



1 Third Ann. Rept. U. S. Geol. Survey, 1883, p. 307. 



