724 THE ILLINOIS GLACIAL LOBE. 



A well near Alexander, on the farm of Isaac Tyndall, was sunk to a 

 depth of 1,000 feet without obtaining a flow. Another well was sunk to 

 a depth of 320 feet. Each of the wells yields a small amount of gas, 

 which is struck in Coal Measures strata. The drift at these wells is about 

 90 feet in depth, as follows: 



Section of drift in Tyndall well near Alexander, Illinois. 



Feet. 



Soil and yellovr clay '. 25 



Gray pebbly clay 26 



Blue clay 25 



Clays of variable color 15 



Total drift 90 



At Waverly wells are 20 to 50 feet in depth, and the deeper ones 

 enter rock near the bottom. The loess in that vicinity is only 6 feet in 

 depth. The drift is mainly yellow till, though there is blue till near the 

 base. 



In the vicinity of Franklin rock is usually entered at about 35 feet, 

 but wells are often obtained above the rock. 



SANGAMON COUNTY. 

 GENERAL STATEMENT. 



Sangamon County, situated near the center of the State, contains 

 Springfield, the State capital, which is also the county seat. It has an area 

 of 860 square miles. The northeastern portion of the county is traversed 

 in a westward course by the Sangamon River, and this stream with its 

 tributaries drains nearly all of the county. The drainage from the western 

 and southern portions of the county is northeastward, there being a rapid 

 descent in that direction. The county is well drained, and yet the valleys 

 of most of the streams are very shallow. A coating of loess about 8 feet 

 in average depth caps the glacial drift, and aids greatly in the ready 

 absorption of the excess of rainfall. 



The drift is generally of moderate depth, the distance to rock being 

 seldom more than 50 feet. Where it is mainly till, wells are frequently 

 sunk into the underlying Coal Measures for water, the supply from the drift 

 being weak. The conspicuous development of Sangamon soil between the 

 loess and till is discussed on preceding pages. 



