WELLS OF LAKE COUNTY, ILLINOIS. 579 



The well at Mr. Cummings's overflows, although at an altitude about 

 900 feet above tide, and that at Mr. Whittemore's rises nearly to the sur- 

 face. The absorbing area is probably on a moraine south of the wells, 

 which rises to a higher elevation than that of the well sites. All the wells 

 in the above list are mainly through till. In this connection it may be 

 remarked that the moraines of this county appear to be composed chiefly of 

 till, the principal exception being a gravelly area occupying a few square 

 miles in the vicinity of Crystal Lake and thence eastward to Fox River. 



LAKE COUNTY. 

 GENERAL STATEMENT. 



Lake County is situated in the extreme northeast corner of the State, on 

 the border of Lake Michigan. It has an area of 490 square miles, and the 

 county seat is Waukegan. The eastern portion of the county is traversed 

 from north to south by the Des Plaines River, while the western portion 

 is touched by Fox River. There are numerous lakes in the western half 

 of the county, situated among the knolls and ridges of the Valparaiso 

 morainic system. There are also extensive marshes and sloughs bordering 

 these lakes and Fox River. The Valparaiso morainic system, which occu- 

 pies much of the western half of the' county, stands 200 to 300 feet above 

 Lake Michigan. Other moraines, occupying a narrow belt between the Des 

 Plaines and Lake Michigan, stand 100 feet or more above the lake. 



The drift of this county probably has an average thickness of more 

 than 200 feet. The few wells which enter rock find a rock surface lower 

 than the level of Lake Michigan, and several other deep borings penetrate 

 below the level of Lake Michigan without entering rock. It is scarcely 

 probable that the rock surface will average an elevation as great as the 

 level of the lake (580 feet above tide). The upper portion of the drift, to 

 a depth of about 150 feet, is chiefly a soft blue till, thought to be of Wis- 

 consin age. Beneath this occasional borings in Lake, as in neighboring 

 counties on the south and west, enter a hard till, thought to belong to the 

 earlier stages of glaciation. 



The wells in this county usually obtain water at moderate depths, from 

 gravel or sand associated with the till. Such wells, however, are often 

 weak, and farmers have occasionally sunk to depths of 200 feet or more in 

 order to obtain a larger supply. 



