204 THE ILLINOIS GLACIAL LOBE. 



half mile. The following is the section of the air shaft as furnished by 

 Charles Hansel, of Decatur: 



Section of drift in an air shaft at Decatur, Illinois. 



Feet. 



Soil and loamy clay 25 



Sand and water, flow of 400 gallons per minute 30 



Blue clay 4 



Driftwood and soil 2 



Green sand 4 



Gray sand - 6 



Hard blue clay 9 



Sand and gravel, fine strata 37 



Hardr.au 23 



Total drift 140 



The bed of driftwood and soil was struck at about the level of the sur- 

 face of the older drift sheet outside the moraine; it may be either Peorian 

 or Sangamon. In the coal shaft two soils are reported, of which the lower 

 one appears to be in the midst of the older drift; at least it is placed below 

 a gravelly hardpan, such as is commonly reported when the older drift is 

 struck. The following is the section as published in the Geology of Illinois: 



Section of drift in a coal shaft at Decatur, Illinois. 



Ft. iu. 



Soil and clay-. - 31 



Sand with two clay bands 11 



Quicksand 2 6 



Tough clay 4 



Black soil 2 6 



Sand 2 



Clay 3 



Greenish sand 6 



Gravelly hardpan 11 



Black soil 2 



Quicksand 4 



Gravelly clay 24 



Quicksand 6 6 



Total drift 109 6 



Many wells in the vicinity of Decatur are sunk to a depth of about 80 

 feet befoi'e obtaining a strong supply of water. The till is apparently a 

 nearly unbroken sheet. On the moraine west of Decatur, in the vicinity of 

 Harristown, wells are often sunk through blue till to a depth of 100 or 125 

 feet. It is thought that they obtain their supply of water at or near the 

 base of the Shelbyville sheet. North from Decatur, in the vicinity of 

 Maroa, about 60 feet of blue till is penetrated before water-bearing sand or 



