588 THE ILLINOIS GLACIAL LOBE. 



height 34 feet above lake level, or 614 feet above tide. The well reaches 

 the Potsdam sandstone. An analysis of the water is presented in the 

 Seventeenth Annual Report of this Survey. 1 The temperature of the water 

 is 61.7 degrees Fahr. Many wells are obtained in this city at a depth of 

 35 feet or less near the bottom of the beach sand. The peaty deposits 

 which occur at that horizon in some cases give the water an unpleasant 

 odor. The use of private wells is decreasing, being supplanted by the 

 public supply which is pumped from Lake Michigan. 



In the vicinity of Niles Center several wells strike rock at depths 

 ranging from 85 to over 100 feet. The gravel and sand of the lake beach 

 is 8 to 12 feet in depth. The underlying glacial drift is mainly till. 



At Morton a well 115 feet in depth enters rock at about 100 feet. The 

 drift is mainly blue till. 



In Bowmanville and vicinity several wells near the Chicago River 

 reach a depth of 80 feet without striking rock. In some instances they 

 penetrate about 20 feet of beach gravel. A well at Rose Hill Cemetery, 

 near Bowmanville, strikes rock at 100 feet. The upper 30 feet is gravel 

 and sand, beneath which is a compact till extending to the rock. 



In several suburbs in the northwest part of Chicago rock is struck in 

 artesian wells at 60 to l00 feet, as follows: 



Drift in artesian wells in northwest part of Chicago. 



Feet. 



Jefferson Park 68 



Irving Park 79 



Montrose - - 60 



Norwood Park 90 



Near County Infirmary 71 



Same locality 101 



Oak Park - 65, 85, and 45 



Near Cragin 20 



In all of these wells the greater part of the drift is blue till. The 

 beach gravel and sand seldom amount to more than 5 or 10 feet. 



A well at River Park, near the Des Plaines River, 115 feet in depth, 

 enters rock at 100 feet. A well at Turner Park obtains water from sand 

 below till and just above the rock at a depth of 80 feet. Mr. Koch, near 

 Dunning, has a well 114 feet in depth which did not reach rock. "Wells in 

 the vicinity of Gralewood, 60 feet in depth, are mainly through till and do 

 not reach rock. Wells at Maywood, 40 feet in depth, do not reach rock, 



1 Part II, p. 827. 



