20B THE ILLINOIS GLACIAL LOBE. 



feet in depth, and none of them readied the rock. They penetrate about 

 100 feet of soft till of blue color, probably referable to the Shelby ville 

 sheet, beneath which a harder, brownish-blue till is entered, which seems 

 referable to the Illinoian drift. The village of Atlanta obtains its water- 

 works supply from two 8-inch wells 151 feet in depth. The following 

 detailed record of the drift beds penetrated was furnished by J. S. Bevan, 

 mayor of Atlanta: 



Section of a well at the waterworks at Atlanta, Illinois. 



Feet. 



Black soil 3 



Yellow clay ; - 15 



Blue clay - 10 



Gray sand and gravel - 10 



Blue clay - 



Sand and gravel.. 9 



White clay and sand 7 



Blno clay with gas 3 



White sand and gravel - - 10 



Sand 6 



Dry sand and gravel with gas 13 



Blue clay - - f '1 



Clay, sand, gravel, aud gas - -- -- 16 



Hardpan - 9 



Black drift (probably Peorian soil) G 



White clay (probably Io wan. silt). - - 2 



Green clay (probably Io wan silt) - 1 



Hardpan (probably Illinoian till) 10 



Gravel and water — 12 



Total ■ 151 



The black drift noted in this well section has about the level of the 

 plain outside the Shelbyville drift sheet, and is probably a soil formed above 

 the Iowan silt. 



In the vicinitv of Delavan the drift over an area of several square 

 miles may exceed 300 feet in depth, for the Shelbyville sheet here 

 encroaches on a preglacial valley; the thickness in one well is 313 feet. 

 The city waterworks well is 240 feet in depth and has the following section, 

 furnished by J. D. Mount, city marshal: 



Section of the well at waterworlcs in Delavan, Illinois. 



Feet. 



Yellow bowlder clay (Shelbyville sheet) --. 15 



Blno bowlder clay (Shelbyville sheet) 60 



Black muck with wood (probably Peorian soil) - 6 



Solt green clay (probably Iowan silt) 8 



Hard gray bowlder clay (probably Illinoian till) 30 



Gray sand containing water - 122 



Total 240 



