WELLS OF JACKSON COUNTY, ILLINOIS. 779 



area of 580 square miles. Big Muddy River traverses its southern portion 

 and Beaucoup Creek divides the northern portion nearly centrally. This 

 county, like Randolph, has an elevated limestone tract along the Mississippi 

 bluffs, from which there is a descent northeastward to the plains underlain 

 by the Coal Measures. The elevated portion of this county has such a 

 broken surface that it is but sparsely settled. At the south it extends beyond 

 the glacial boundary and preserves all the ruggedness . of the preglacial 

 topography. The western portion appears to have been covered by the ice 

 sheet, but the drift only partially fills the preglacial valleys. 



The belt of ridged drift which has been traced southeastward across 

 Randolph County to the border of this county is represented by occasional 

 low ridges and knolls along the north border of the elevated tract just dis- 

 cussed as far east as the plain bordering Beaucoup Creek. The best 

 development is found 1 to 4 miles southeast of Ava, along the turnpike 

 leading from Ava to Murphysboro. The belt has not been identified in the 

 eastern portion of the county. Northeast from this ridged belt there is 

 generally present a sheet of typical till 20 to 40 feet or more in depth, and 

 a similar deposit is found in the lowlands of the northeastern part of the 

 county. The wells often penetrate a bed of blue silt containing wood at 

 depths of 30 feet or more, beneath the pebbly glacial clays. Several 

 instances are noted in the Geology of Illinois, and other' instances came to 

 the writer's notice, but no exposures of the silt were found by the writer. 



On the elevated and hill}' portions of the county the residents depend 

 largely upon cistern water, but a few wells have been obtained at moderate 

 depth. In the lower portions of the county wells are obtained at 20 to 50 

 feet, often without entering rock. Those in the Mississippi Valley are 30 

 to 40 feet in depth and mainly through a fine sand. 



INDIVIDUAL WELLS. 



The wells at Campbell Hill, in the northwest part of the county, have 

 in a few instances been sunk into rock, which is reached at a depth of about 

 40 feet. The majority, however, obtain water from the glacial drift. 

 Records of wells near this village -appear in the Geology of Illinois, in 

 which a blue mud containing wood is struck below the glacial drift at 

 depths of 30 to 35 feet. 



