wells op Mchenry county, Illinois. 575 



In the southwest township of the county, in the vicinity of Irene, wells 

 are usually sunk into the rock, though the drift in places exceeds 30 feet. 

 The Illinois Central Railway cutting, immediately west of Irene, shows an 

 extensive exposure of black soil containing molluscan shells underneath a 

 sheet of till. The soil appears to separate the Iowan till sheet from the 

 Illinoian in which case it is referable to the Sangamon interglacial stage. 



McHENRY COUNTY. 

 GENERAL STATEMENT. 



McHenry County is situated immediately east of Boone, on the north 

 border of the State, Woodstock being- its county seat, and has an area of 

 624 square miles. Its western portion is drained by the Kishwaukee and 

 tributaries westward to Rock River, while the eastern portion is drained 

 southward through Fox River, which has its course near the eastern border 

 of the county through a series of lakes and sloughs. This is one of the 

 most elevated counties in the State, several square miles on its northern 

 border being above the 1,000-foot contour, while much of the county 

 stands above 900 feet. 



The greater part of the county is occupied by a system of moraines 

 formed at the Wisconsin stage of glaciation, there being only a narrow 

 strip on the western border of the county, scarcely a township in average 

 width, which lies outside its outer morainic system. This is underlaid 

 largely by a gravel overwash from the moraine, and is therefore of Wisconsin 

 age. There are a few outcrops of rock near the Kishwaukee in the western 

 portion of the county at an altitude about 800 feet above tide, but these 

 appear to stand above the general level of the rock surface and represent 

 probably the tops of preglacial ridges or hills. Several deep wells scattered 

 widely over the county have shown the presence of a very thick deposit of 

 drift. It is probable that the average depth is not less than 200 feet, or 

 nearly twice the average depth of drift for the State. 



The wells for household use usually obtain water at moderate depth 

 (20 or 30 feet), but wells for stock are often sunk to depths of 100 or even 

 200 feet. Dairying being one of the principal industries of the county, a 

 large number of farmers have sunk deep wells to supply their cattle. The 

 records of only a few of these were obtained, but they are thought to be 

 representative. 



