728 THE ILLINOIS GLACIAL LOBE. 



gray or blue tills of the earlier sheets beneath it and which extend over the 

 country to the west. 



Tubular wells are often sunk in the portion of the county covered by 

 the Wisconsin drift to a depth of 100 to 150 feet, and occasionally to 

 greater depths without reaching rock. A large number of wells, however, 

 are obtained from this drift sheet at depths of but 20 to 40 feet. On the 

 plain outside the limits of the Wisconsin drift the wells are often obtained 

 at but 12 to 15 feet, and they seldom exceed 25 feet in depth. 



INDIVIDUAL AVELLS. 



At Niantic, on the plain in the western part of the county, wells are 

 usually obtained in sand and gravel at a depth of 15 feet. A coal shaft at 

 this village penetrates the following- beds of drift : 



Section of drift beds in coal shaft of Niantic, Illinois. 



Feet. 



Soil and brown clay 11 



Sand and gravel 4 



Till of grayish color 25 



Hard blue till 10 



Soft clay - 15 



Hard gray till ....10 



Soft clay of brown color 7 



Total drift 82 



At Harristown, on the crest of the moraine east of Niantic and about 

 90 feet higher, several tubular wells have been sunk to depths ranging from 

 7o to 152 feet. The deepest, at the residence of Dr. John Connelly, has 

 the following' section : 



Feet. 



Yellow till 15 



Soft blue till, about 100 



Hard grayish-blue till 37 



Gravel and water at bottom. 



Total 152 



In several instances the wells near Harristown appear to obtain their 

 supply from the base of the Wisconsin drift, just below the soft blue till, at 

 a depth of 100 to 110 feet. The few which are sunk deeper usually enter 

 a harder till, as in the section just noted. East from Harristown, toward 

 Decatur, the wells are often sunk to depths of 85 to 110 feet, mainly through 

 a soft blue till. The elevation is a few feet lower than on the crest of the 

 moraine at Harristown, and the wells probably reach the bottom of the 

 Wisconsin drift. 



