616 THE ILLINOIS GLACIAL LOBE. 



at 25 feet and rock at 67 feet. A well in sec. 26 entered rock at 78 feet 

 without penetrating any blue clay, the following being its section: 



Section of a well near Garden Plain, Illinois. 



Feet. 



Loess 15 



Fine sand 15 



Coarse sand, becoming gravelly near bottom 48 



Rock 5 



A well in sec. 11, 106 feet in depth, enters rock at about 100 feet. Pro- 

 fessor Udden reports that in sees. 1 and 2 of this township rock is struck at 

 a depth of only 30 feet. 



In the vicinity of Union Grove and thence east to Morrison the wells 

 usually enter rock at less than 30 feet, but a well in sec. 18, 70 feet in depth, 

 penetrates rock only 2 feet. It is entirely through sand, and is reported to 

 have penetrated snail shells near the base of the sand. A well near the 

 center of sec. 12 enters rock at 63 feet, and is reported to be entirely through 

 loess and sand, except 3 feet of gravel at the top of the rock (Udden). 



The public water supply for the city of Morrison is obtained from 

 springs in Rock Creek Valley. An artesian well was sunk at this city to a 

 depth of 1,190 feet. Mr. S. D. Gossert, editor of the Whiteside Sentinel, 

 reports that the head is sufficient to carry the water 15 feet above the sur- 

 face, but the well was not in use at the time his communication was received 

 (August, 1895). Mr. Grossert reports that the wells in the vicinity of Mor- 

 rison range from 35 to about 80 feet in depth, and are in nearly all cases 

 obtained from the rock. Southeast of Morrison, near the south border of 

 the township, the present writer obtained records of several wells which do 

 not enter rock at depths of 40 or 50 feet, but other wells in that vicinity 

 enter rock at about 20 feet. 



Rock outcrops extensively in the vicinity of Rock Falls and Sterling. 

 But a well in sec. 33 of this township is reported by Professor Udden to 

 penetrate drift 84 feet and to terminate in limestone at 313 feet. With the 

 exception of 5 feet near the bottom of the drift, there was no clay in this 

 well section, the greater part being sand and fine gravel. 



The public water supply at Sterling and also at Rock Falls is obtained 

 from an artesian well 1,450 feet in depth, which terminates in the Potsdam 

 sandstone. 1 The well overflows at an elevation about 670 feet above tide 



1 The Manual of American Waterworks, 1897, reports a depth of 1,600 feet. 



