GEOLOGICAL AND NATURAL HISTORY SURVEY. 33 



1. Yellow, pebbly clay • • 12 feet 



2. • Gravel • • 2-3 ' ' 



3. Blue, pebbly clay, with sand pockets 100 



4. Sand and reddish, pebbly clay, in alternate layers, each 10 — 15 



feet • • 107 " 



5. Whitish, sandy clay ■ ■ 4 " 



6. Sand and gravel 3 '" 



Depth 230 feet 



Mr. Spiimer estimates the depth of the bhie till along the 

 divide between the F"ox and Des Plaiiies Rivers in southern Lake 

 County to be 125 to 150 feet and wells occasionally obtain water 

 in gravel iinmediately beneath this till. 



Mr. William McWendle, a well borer at Oak Glen, reports 

 two wells at Barrington that strike rock at 254 and 250 feet, re- 

 spectively. To a depth of about 160 feet in each well the drift is 

 mainly a soft blue till. Considerable cobble was encountered at 

 this depth. Below the cobble is a lighter colored clay harder and 

 more pebbly than the blue clay and apparently belonging to an 

 older drift sheet. 



Mr. A. W. Van Dervolgan, of Batavia, reports the following 

 section of a boring on the crest of the moraine south of Barring- 

 ton, in Sec. 22, Barringtown Towns'hip, which is the thickest sec- 

 tion of drift yet noted in the Chicago Area: 



1. Yellow and blue, pebbly clays, about 160 feet 



2. Quicksand, about • • 15 



3. Reddish, pebbly clay, hard and dry, about 140 



Depth 315 feet 



The well was abandoned without reaching the bottom of 

 the drift and a second boring was made only five rods distant 

 from it, which furnishes a good supply of water at 170 feet. 



Mr. M. Sneible, of Palatine, has found in his experience as a 

 well borer that the yellow surface clays in the vicinity of that vil- 

 lage vary in depth from six to fifteen feet and that tbe blue bowlder 

 clay is lOO to 125 feet in depth. He usually finds sand or gravel 

 beneath the blue clay and here obtains the wells, but occasionally 

 a thin bed of cemented gravel is penetrated or limestone is en- 

 tered just below the blue clay before obtaining a well. In sev- 

 eral instances he has reached the bottom of the drift at 150 to 165 



