WELLS OF PIKE COUNTY, ILLINOIS. 719 



Two of the ridges extend but little south of Pittsfield, but a third ridge, 

 which, as noted above, follows the east border of Bay Creek, continues 

 southeastward to the Illinois bluff, which it strikes between Montezuma and 

 Bedford. These ridges constitute the highest land within the county, and 

 reach in places an elevation of nearly 900 feet, and throughout much of 

 their course are about 800 feet above tide. The rivers bordering the 

 county have an elevation of less than 450 feet above tide, or about 400 feet 

 below the general level of these ridges. Much of the upland in the county 

 stands nearly 300 feet above the bordering streams. 



Aside from the drift ridges just mentioned, the drift of the county is a 

 thin deposit, scarcely forming a continuous coating. But in the drift ridges 

 a thickness of about 100 feet is in places attained, and the thickness is 

 seldom less than 50 feet. The drift in these ridges consists largely of a 

 clay in which pebbles are less thoroughly intermixed than in typical till. 

 The dumps of some wells examined, which reached the depth of 60 feet, 

 show scarcely a handful of pebbles on their surface, while neighboring wells 

 or natural exposures may contain a large amount of stony material. This 

 imperfect intermingling of the stony and clayey material is probably due 

 to the derivation of much of the drift from the immediate vicinity and the 

 consequent short distance that it was transported. The loess forms a heavy 

 deposit on the borders of the Illinois and Mississippi rivers, its usual thick- 

 ness being 25 or 30 feet, but in the interior of the county its thickness 

 decreases to scarcely 10 feet. On the higher portions of the drift ridges 

 it is in places only 4 or 5 feet in depth. 



Along the drift ridges wells are often obtained without entering the 

 rock, but elsewhere on the uplands strong wells are seldom obtained in 

 the drift. In the valleys of the Mississippi and Illinois wells are usually 

 obtained in sand and gravel at about the level of these streams. 



INDIVIDUAL WELLS. 



In the vicinity of Barry, in the northwest part of the county, the wells 

 are usually obtained in rock at a depth of 60 to 85 feet, The loess and 

 drift is 16 to 35 feet in depth. The public water supply is from a well 

 2,510 feet in depth, which has a head 135 feet below the surface, except 

 when filled with surface water after an intermission from pumping. The 

 water, unless diluted with surface water, is too salt for domestic use and the 

 majority of the citizens depend upon private wells. 



