678 THE ILLINOIS GLACIAL LOBE. 



is entered at about 30 feet, but wells are usually obtained without enter- 

 ing the rock. A drift ridge leading east from this town and standing 30 

 or 35 feet above the general level of the plain is found to have a black soil 

 beneath till at about the level of its base. This soil has been struck in 

 several wells. 



At Abingdon wells are usually obtained from rock at depths of only 25 

 or 30 feet. The drift is in places but 1 5 feet in thickness. 



WARREN COUNTY. 

 GENERAL STATEMENT. 



Warren County is situated immediately west of Knox and has an area 

 of 540 square miles, with Monmouth as the county seat. The drainage is 

 mainly westward through Henderson River and other streams into the 

 Mississippi. The southeastern portion of the county, however, drains 

 eastward to Spoon River. The features of this county are very similar to 

 those of Knox, there being a well-drained surface and comparatively thin 

 covering of drift. The loess is fully as thick as in Knox County and 

 equally pervious to water. At the base of the loess numerous springs are 

 to be seen where it outcrops along the sides of ravines. 



INDIVIDUAL WELLS. 



At Monmouth the public water supply is from two wells, each about 

 1,227 feet in depth. They enter the St. Peter sandstone 156 feet. One 

 was cased to the top of this sandstone, but the other was not cased to so 

 great a depth, for the reason that a water vein was found at a depth of 

 about 935 feet which seemed desirable to admit to the well. The head in 

 the well cased to the St. Peter sandstone is 60 feet below the surface and 

 675 feet above tide. No data have been obtained concerning the head in 

 the other well. The capacity of the first-named well is estimated at 200 

 gallons per minute. An analysis of its water appears in the Seventeenth 

 Annual Report of this Survey. 1 Private wells of considerable strength 

 are obtained in the vicinity of Monmouth at a depth of about 60 feet, in 

 some cases from the glacial drift. There are also shallower wells of less 

 strength. 



Part II. p. 827. 



