WELLS OF HANCOCK COUNTY, ILLINOIS. 681 



HANCOCK COUNTY. 

 GENERAL STATEMENT. 



Hancock County borders on the Mississippi below Henderson County 

 and opposite the extreme southeast corner of Iowa. It has an area of 769 

 square miles, and Carthage is the county seat. Although bordering the 

 Mississippi River, a considerable portion of the county is tributary to the 

 Illinois River. In the north part of the count}' the divide between 

 the Illinois and Mississippi rivers is only 3 or 4 miles from the east bluff of 

 the Mississippi. The principal stream leading to the Illinois in this county 

 is Crooked Creek, which drains the northeastern fourth of the county. The 

 principal stream tributary to the Mississippi is Bear Creek, which drains the 

 southwestern fourth of the county southward into Adams County and thence 

 westward into the Mississippi. Along much of the northern half of the 

 border of this county the Mississippi River is in a new course and occupies 

 the entire width of its valley. The distance between bluffs is but little 

 more than a mile. In the remainder of the border the river is in a pregla- 

 cial course, Avith bottoms 6 or 8 miles in width. These bottoms are mainly 

 on the Missouri side, though near the south line they extend 3 or 4 miles 

 into this county. The uplands stand 150 to 200 feet above the river and 

 are generally plane. There is, however, a well-defined drift ridge leading 

 southward from Warsaw a short distance east from the river bluff, a ridge 

 which, as previously described, apparent^ marks the western limit of the 

 Illinois glacial lobe. 



The thickness of the drift varies greatly, owing to the presence of deep 

 preglacial valleys which have been filled to a level as great as the border- 

 ing uplands. In such valleys rock is not usualty entered at less than 200 

 feet, but on the bordering uplands it may be entered at 20 feet. There is 

 usually, however, 50 or 60 feet of drift on the preglacial uplands. One of 

 the most conspicuous of these buried valleys revealed by the wells is found 

 in the central portion of the county, near Carthage, and a portion of its 

 course is along the present water parting between the Illinois and the Mis- 

 sissippi rivers. This valley apparently leads southward into Adams County 

 along a line a short distance east of the valley of Bear Creek. Perhaps its 

 lower course is followed by Bear Creek. 



The drift is mainlj- a compact till, and in places wells are difficult to 

 obtain. A large number of wells have been sunk to a depth of 100 to 200 



