GEOLOGICAL AND NATURAL HISTORY SURVEY. 35 



till exposed in the east bluff. Just below Lemont a blue till rests 

 immediately on the limestone, but frequently iri that locality there 

 .is sand or gravel 'at the base of the drift. In the west bluff, oppo- 

 site Lemont, there are large accumulations of sand, gravel and 

 cobble, in portions of which bowlders and bowlderets are im- 

 bedded, While in other portions assorting is quite perfect. There 

 are also places where a very fine, partially cemented, sand, almost 

 as fine as loess, caps the deposit. 



In the portion of the moraine east of the Des Plaines River 

 the yellow clay has a depth of about ten feet. It is underlain by 

 a grayish-blue bowlder clay, which carries a sufficient number 

 of water-bearing veins to furnish abundance of water for wells. 

 There is less difficulty experienced in getting good wells at slight 

 depth here than in the portion of the moraine west of the Des 

 Plaines River. There are very few tubular wells and these seldom 

 exceed sev^enty-five feet in depth, while the majority of those along 

 the crest of the moraine have a depth of but forty to sixty-five 

 feet. Consequently there is a less complete knowledge of the 

 deeper structure of the drift than on the portion west of the Des 

 Plaines River. The following r'^present the deepest wells of which 

 sections were obtained: 



At Beecher Station a well io6 feet in depth is principally 

 in blue bowlder clay and obtains water in a gravel at the depth 

 mentioned. 



On the crest of the moraine at C. L. Pease's residence, one 

 mile north of Goodenow, a well 112 feet in depth is in blue 

 bowlder clay to the water-bearing gravel at bottom. 



J. O. Piepenbrink, Section 11, Crete Towns'hip, has a well 

 106 feet in depth, which has the following section: 



1. Yellow, pebbly clay, of reddish cast 20 feet 



2. Grayjsh-blue, pebbly clay 85 " 



3. Coarse sand i " 



Depth 106 feet 



Mr. Piepenbrink finds the blue clay less pebbly than the 

 yellow clay and the blue clay varies greatly in hardness in differ- 

 ent wells on his farm and also varies at different depths in the 

 same well. 



In the villag'e of Crete nearly all the wells enter sand at slight 

 depth, and cellars are frequently drained by boring a few feet in • 

 their bottoms to a dry sand, which absorbs their water. The 



