COMPOSITE MORAINIC BELT OF NORTHERN ILLINOIS. 297 



PORTION OF COMPOSITE BELT WEST OF FOX RIVER. 

 GENERAL FEATURES. 



Aside from the Marengo Ridge just described, there is a belt from 

 8 to 15 miles in width, on the west side of Fox River, in McHenry and 

 Kane counties, which is strongly morainic, there being only a few small 

 areas, of 1 to 3 square miles each (aside from marshes and swamps included 

 among the morainic knolls), in which the surface is level. The belt is 

 more elevated on the west border than in the vicinity of Fox River. Its 

 general elevation there is not markedly different from that of the crest of 

 the Marengo Ridge. At the State line it rises above the 1,000-foot contour, 

 one point being 1,040 feet above tide (Rolfe). A point a mile south of 

 Alden rises above 1,000 feet. Along much of the divide between the 

 Kishwaukee and Fox rivers, from the State line southward to Crystal 

 Lake, the altitude is above 950 feet. In southern McHenry County and 

 in Kane County few points reach 950 feet, but much of the divide rises 

 above 900 feet. 



Fox River enters the State at an elevation of 766 feet (Rolfe) and falls 

 about 25 feet in crossing McHenry County, a distance by course of stream 

 of over 30 miles. In Kane County its descent is more rapid, there being 

 a fall of 125 feet in a distance no greater than that traversed by the stream 

 in McHenry County. The stream is in the midst of morainic knolls and 

 ridges as far south as Geneva, beyond which it has a plain on its west 

 border. These ridges often rise abruptly 80 or 100 feet above the level of 

 the stream. From the valley of Fox River, in McHenry and Lake counties, 

 marshy valley-like tracts extend back several miles to the west and 2 to 3 

 miles to the east. These are traversed by sluggish streams similar to the 

 upper course of the river. 



Although the western border of this composite belt is, on the whole, 

 more elevated than the district immediately bordering Fox River, it does 

 not present so rough a surface, except perhaps in central Kane County, 

 where a few square miles present a very sharp knob-and-basin topography. 

 If a strip 3 or 4 miles wide along the west side of Fox River be excepted, 

 the moraine in McHenry County presents few knolls that exceed 40 feet in 

 height. The great majority are 25 feet or less. On the borders of Fox 



