752 THE ILLINOIS GLACIAL LOBE. 



In the vicinity of Woburn wells on low drift ridges reach a depth of 

 40 feet and are largely through gravel. On the plain east of Woburn wells 

 are usually obtained at about 25 feet and are mainly through till. 



In the east part of the county, near Pleasant Mound, wells are usually 

 obtained at 25 or 30 feet without entering rock. A well on a knoll 1£ 

 miles southeast from Pleasant Mound entered rock at 48 feet, which is about 

 the level of the base of the knoll. 



FAYETTE COUNTY. 

 GENERAL STATEMENT. 



Fayette County is situated in the south-central part of the State, and 

 has an area of 720 square miles. Vandalia is the county seat. The Kas- 

 kaskia River leads nearly centrally from northeast to southwest through the 

 county and has broad bottoms averaging probably 3 or 4 miles in width. 

 No large tributaries enter within the limits of this county. Like Bond 

 Count)' a portion of Fayette has imperfect drainage, due in part to the poor 

 development of drainage lines and in part to the compact white clay which 

 caps the surface. 



A system of prominent drift ridges is found in the southwestern part 

 of the county. The most prominent belt leads from Vera past Vandalia to 

 Pleasant Mound in Bond County. It stands in some places 100 feet above 

 the bordering plains and presents a complex series of ridges and knolls 

 with an average breadth of 2 miles. The remainder of the county has a 

 nearly plane surface. 



No records of wells have been obtained by the writer in this county 

 except at Vandalia, and the thickness of the drift is known at but few places, 

 where outcrops of rock occur. There is apparently a filling of about 100 

 feet along the Kaskaskia River and its preglacial tributaries, but on the 

 uplands the thickness is only 20 to 40 feet. 



INDIVIDUAL WELLS. 



Wells on the drift ridges in the vicinity of Vandalia frequently reach a 

 depth of 75 feet and are mainly through a gravelly drift. The Manual of 

 American Waterworks (1897) reports that a waterworks system is about 

 to be constructed which will obtain its supply from the Kaskaskia River. 



