692 THE ILLINOIS GLACIAL LOBE. 



In the vicinity of Green Valley village, on the portion of the Illinois 

 bottoms northwest from Delavan, several wells have been sunk to a depth 

 of over 100 feet through sand and gravel without entering rock. In one 

 case a depth of 145 feet was reached. At the east border of the valley, 

 however, the wells in some cases penetrate 40 to 60 feet of clay before 

 entering sand and gravel. One in sec. 6, T. 22, R. 4 W. penetrated 60 

 feet of chtv, then 75 feet of fine sand, and obtained water in the gravel at 

 bottom. Another in sec. 7 of the same township penetrated 62 feet of clay 

 and 30 feet of sand, when a water-bearing gravel was struck. 



At Hopedale the railway well is 195 feet in depth without reaching 

 rock. It was mainly through till to a depth of 160 feet, beneath which 

 sand was encountered. A bed of black muck was passed through between 

 till sheets, but the precise depth was not noted. Between Hopedale and 

 Armington, a well on the farm of Robert Pratt, 250 feet in depth, is thought 

 to have struck rock at the bottom. The well mouth is about 650 feet above 

 tide. 



At Mackinaw a boring 160 feet in depth was mainly through till to 

 140 feet, beneath which sand was entered which yields an inflammable gas. 

 Wells at this village usually obtain water in sand and gravel between till 

 sheets at a depth of 35 or 40 feet. The waterworks well is 65 feet deep, 

 and is scarcely adequate to supply the village. 



In the vicinity of Cooper, on the crest of the inner strong ridge of the 

 Bloomington morainic system, at an altitude about 820 feet above tide, wells 

 are frequently sunk to a depth of 150 feet, mainly through till. In some 

 wells a black muck is found between tills nearly 150 feet below the surface. 



McLEAN COUNTY. 

 GENERAL STATEMENT. 



McLean County is situated east of Tazewell, with Bloomington as the 

 county seat. It is the largest county in the State, its area being 1,166 

 square miles. The northern half of the county is tributary to the Mackinaw 

 River, with the exception of a few square miles in the northeast corner, 

 which are drained northward to the Illinois-Vermilion. The southern half 

 is drained by the Sangamon and its tributaries. The valleys are all small, 

 within the limits of the county, and in many cases are mere ditches cut to 



