676 THE ILLINOIS GLACIAL LOBE. 



depths have been found in other wells in the valley at this city. They show 

 the rock floor to be at an altitude of 350 feet, or 80 feet below the Illinois 

 River. Possibly a deeper portion of the old valley is to be found farther 

 east, as these wells are all situated near the west bluff. 



Between Peoria and Chillicothe, on a sandy terrace of the Illinois 

 River, standing about 100 feet above the present stream, several wells have 

 been sunk to depths of 90 to 120 feet. They apparently obtain water at 

 about the level of the Illinois River. A few wells on this terrace near the 

 west bluff obtain water at 50 to 75 feet. 



The Manual of American Waterworks reports that the public water 

 supply at Chillicothe is from driven wells, depth not given. 



KNOX COUNTY. 

 GENERAL STATEMENT. 



Knox County is situated in western Illinois immediately west of Stark 

 and Peoria counties. It has an area of 720 square miles, and Gralesburg' is 

 the county seat. The southeastern portion of the county is crossed by 

 Spoon River in a southwestward course, and about three-fourths of the 

 county is tributary to that stream. The northwest one-fourth of the county 

 drains directly westward to the Mississippi River through Pope Creek and 

 two branches of Henderson River. The county has a good surface drain- 

 age, the drainage systems being well matured and the slopes between 

 streams sufficiently rapid to insure the discharge of water not absorbed by 

 the soil. The loess, which forms a capping about 15 feet in thickness, is 

 sufficiently porous to readily absorb a large part of the rainfall and return 

 it to the crops in seasons of drought. 



The glacial drift is generally but 20 or 30 feet in depth, but in places 

 where valleys have been filled the depth may reach 100 feet or more. The 

 average of 10 borings which enter rock is found to be 35 feet, and this is 

 thought to fairly represent the upland average for the county. The majority 

 of wells are obtained in the drift, some being sunk only to the base of the 

 loess. The strong wells, however, usually penetrate the glacial drift a short 

 distance. 



INDIVIDUAL WELLS. 



At Galesburg the public water supply is obtained in part from wells in 

 the drift and in part from deep wells sunk to the St. Peter sandstone. The 





