600 THE ILLINOIS GLACIAL LOBE. 



the county drains northward through the south fork of Kishwaukee River. 

 The southeastern part is tributary to Fox River. Like the counties to the 

 east, it is so imperfectly drained that much artificial drainage has been made, 

 both by surface ditches and by tiling. 



The Bloomington morainic system which crosses the central portion in 

 a northeast-southwest direction rises about 100 feet above the district on the 

 outer border. There is on the inner border a gradual descent to the valley 

 of Fox River across a plain dotted with only occasional knolls. 



The drift is probably as heavy as in any of the counties of northern 

 Illinois (except perhaps Bureau County), there being in 22 borings which 

 reach rock an average thickness of 151 feet, while 68 other deep wells which 

 do not reach rock show an average of 101 feet. The portion on the north 

 border of the county outside the morainic system has scarcely 50 feet of drift, 

 and as it comprises an area of fully 100 square miles it materially reduces 

 the average for the county. As in the counties to the east, the drift is largely 

 a blue till, and occasional instances of the occurrence of a buried soil near 

 or perhaps below the level of the base of the Wisconsin drift have come to 

 notice. 



In a large part of the county dairying is the principal pursuit, and 

 many deep wells have been sunk to supply the stock or to furnish water for 

 the creameries and cheese factories. Many of these wells exceed 100 feet 

 in depth, and wells 200 feet or more in depth are not rare. 



INDIVIDUAL WELLS. 



In the northwest township of the county there are few deep wells, 

 water usually being obtained at 25 to 40 feet. A well in sec. 36, however, 

 reached a depth of 75 feet without entering rock. At several points within 

 the township the rock outcrops at a level not more than 25 feet below this 

 well mouth, or about 800 feet above tide. A flowing- well in sec. 35 is sup- 

 plied from gravel below till at a depth of 22 feet. 



In T. 42, R. 4 E., rock outcrops are nearly continuous along the Kish- 

 waukee Bluffs up to an altitude about 750 feet above tide. A few wells in 

 the vicinity of the river penetrate 40 feet or more of drift. On the south 

 border of the township there is a rise of 100 feet or more to the morainic 

 system referred to above, and wells here exceed 100 feet in depth without 

 reaching rock. One at Mr. Leander Roberts's, in sec. 32, has a depth of 132 



