298 THE ILLINOIS GLACIAL LOBE. 



River, as already noted, ridges and knolls in some cases reach a height of 

 80 or 100 feet. Numerous saucer-like depressions and occasional well- 

 defined basins appear in all parts of this belt. 



In northeastern McHenry County there is a small gravel plain known 

 as "English Prairie," which stands about 100 feet above Fox River and 

 occupies perhaps 3 square miles. It is about as elevated as neighboring 

 portions of the moraine and is bordered by morainic knolls and ridges on 

 every side. In the vicinity of Crystal Lake and Gary, in southeastern 

 McHenry County, there is an elevated gravelly tract covering several 

 square miles in which the surface is gently undulating and more subdued in 

 expression than neighboring tracts composed more largely of till. The 

 surface is not so level as in English Prairie. Immediately north of this 

 gravelly tract, in the vicinity of Terra Cotta, there are broad swampy tracts 

 nearly as low as Fox River which separate prominent ridges trending 

 NNE.-SSW. These ridges continue prominent throughout the greater 

 part of Ts. 44 and 45, R. 8 E. 



In northern Kane County there are small plane tracts standing nearly 

 200 feet above Fox River which have been drained by an extensive system 

 of ditches. These are almost completely surrounded by morainic knolls 

 which rise 20 to 40 feet above their surface. Some of these knolls near 

 Gilbert are very sharp. In the vicinity of the line of McHenry and Kane 

 counties Fox River is bordered on each side by morainic tracts rising 150 

 feet or more above the level of the stream, and there is scarcely any marshy 

 land on its borders southward from this line. 



From the vicinity of Elgin southwestward to Lafox there is a belt 3 

 or 4 miles in width on the west side of Fox River in which sharp gravelly 

 knolls and ridges abound. These ridges and knolls show a tendency to 

 arrangement in chains trending nearly east-west, or about at right angles 

 with the trend of the morainic belt. There are, however, not a few excep- 

 tions to this trend, some ridges being nearly in line with the morainic belt. 

 These gravel ridges constitute the most prominent features in this portion 

 of the moraine, many of them being 30 to 40 feet and a few 60 to 75 feet 

 in height. They often rise very abruptly, so that their slopes are cultivated 

 with difficult v. In the majority of cases these chains of knolls and ridges 

 follow depressed areas standing 50 feet or more below the general level, 

 and the present drainage lines in traversing these low belts wind about 



