WELLS OF DUPAGE COUNTY, ILLINOIS. 591 



rises within 2 feet of the surface. Still another well, in sec. 7, T. 35, R. 15 

 E., only 60 feet in depth, encountered rock at the bottom, which may possibly 

 have been a bowlder. 



The public water supply for Chicago Heights is obtained from four 

 wells about 200 feet in depth located on the plain north of the village. The 

 head is not sufficient to cause an overflow. The drift in the vicinity of this 

 village is but 20 or 30 feet in depth and some of the private wells enter the 

 rock; occasionally they are sunk to a depth of 80 or 90 feet. In the dis- 

 trict east of Chicago Heights, as far as the State line, wells are usually 

 obtained at a depth of about 35 feet, from gravel below till. 



DUPAGE COUNTY. 

 GENERAL STATEMENT. 



' Dupage County is situated west of the middle portion of Cook 

 County, and has an area of but 340 square miles. Wheaton, the county 

 seat, is situated near its geographic center. Its drainage is southward, the 

 eastern border being tributaiy to Salt Creek and the middle and western 

 portions to the East and West Dupage rivers, respectively. Like the 

 portion of Cook County on the north, it is poorly drained, although stand- 

 ing much above the bordering plain on the east. The eastern two-thirds of 

 the county is occupied by the Valparaiso moraine, which carries numerous 

 sloughs and basins among its knolls and ridg-es. It affords excellent pas- 

 ture lands and is extensively used in dairying, the leading pursuit of the 

 county. 



On the dairv farms wells are frequently sunk to depths of 100 feet or 

 more. The thickest drift section obtained is 162 feet, and 20 wells which 

 reach rock show an average depth of 86 feet, while 17 of the deep wells 

 which fail to reach rock show an average depth of 94 feet. From these 

 sections, which are distributed widely over the county, the thickness of the 

 drift may be inferred to average not less than 100 feet. The drift is thin- 

 nest in the southwestern portion, on the borders of the West Dupage 

 River, where numerous quarries of limestone have been opened. Rock also 

 comes to the surface near Elmhurst, in the southeast part. The drift in this 

 county, as in northwestern Cook County, consists mainly of a blue till, but 

 beds of sand and gravel are associated with the till at various levels and 

 supply the water for wells. 



