620 



THE ILLINOIS GLACIAL LOBE. 



the more elevated upland near the Mercer County line there is nearly 150 

 feet of drift, mainly a blue till. 



Throughout the county wells usually obtain an abundance of water 

 without entering the rock, though those on the upland are often sunk to 

 depths of 75 or 100 feet. In the valleys northeast of Rock Island wells 

 are usually obtained at depths of 30 or 40 feet without entering rock. 

 Along Rock River and the portion of the Mississippi Valley below Rock 

 Island the drift deposits are thin and wells frequently enter the rock. 



INDIVIDUAL WELLS. 



The following well sections include the deepest of which records have 

 been obtained aside from the artesian wells. About one-half the sections 

 were collected for the Survey by Prof. J. A Udden, who has kindly 

 furnished them for publication in this place. 



Table of wells in Rock Island County. 



