780 THE ILLINOIS GLACIAL LOBE. 



At Ava a coal boring - is thought to have struck rock at 57 feet, but the 

 deepest wells at this village are about 60 feet and do not enter rock. They 

 are mainly through a pebbly clay with which thin sand beds are associate i. 

 A well at D. R. Wills's, on the crest of the drift ridge, 3 miles southeast 

 of Ava, reached a depth of 65 feet without entering rock. Its altitude is 

 fully 300 feet above the Mississippi River. Within 2 miles east from this 

 well rock is struck at only 15 to 25 feet, on ground fully as elevated as the 

 drift ridge. Immediately outside the drift ridge there is scarcely any drift 

 covering the rock. 



At Murphysboro wells are usually obtained at 15 to 30 feet from sand 

 below clay. Coal borings and the well at the Murphysboro brewery pene- 

 trate considerable sand and seldom reach rock at less than 100 feet. The 

 boring at the brewery penetrated 132 feet of drift. An artesian well was 

 sunk at this city many years ago which reached a depth of 1,800 feet. A 

 flow of salt water was struck at about 1,300 feet. The waterworks obtains 

 its' supply from Big Muddy River. 



At Carbondale the wells are usually obtained at 15 to 20 feet in a 

 sandy clay near the base of the drift. A well at the Newell House entered 

 rock at 22 feet and reached a depth of 50 feet. A well at the electric light 

 plant is reported to have penetrated 44 feet of drift, mainly a clay with few 

 pebbles. 



At Elkville, in the northeast part of the county, wells are obtained 

 at about 20 feet from sandy beds associated with the till. A coal boring at 

 this village, reported in the Geology of Illinois, entered rock at 34 feet. 



WILLIAMSON COUNTY. 

 GENERAL STATEMENT. 



Williamson County is situated east of Jackson, with Marion as the 

 county seat, and has an area of 440 square miles. The western half of the 

 county is tributary to Big Muddy River and the eastern to Saline River. 

 With the exception of the south border, which is hilly and unglaciated, this 

 county is a low plain covered to a moderate depth with glacial drift. The 

 thickness of the drift appears to be slightly greater than in counties to 

 the north, but it is not often more than 40 feet. The average is probably 

 25 feet. A capping of silt nearly as compact as the white clay covers the 



