188 GEOLOGY OF ILLINOIS. 



bottom land of Rock river. Between are depressions or troughs, filled 

 with Coal Measure deposits. The heavy seam of coal, worked so exten- 

 sively at Cleveland, rests in one of these basins, and extends half way 

 across Rock river, resting almost directly on the Hamilton limestone. 

 The top of the axis spoken of above, east and west of the coal basin, is 

 higher by several feet than the coal seam. Southward, however, the 

 Coal Measures continue uninterrupted under the bluffs to Coal Valley, 

 and the Minersville mines. 



These natural outcrops of the Hamilton limestone are massive and 

 solid in their structure. The stone breaks with a smooth conchoidal 

 fracture, almost resembling polished marble. On fresh fractures, the 

 color is a beautiful 'bluish- white or pale dove color. A serni-transpa- 

 reut, splintery, horny appearance was noticed in some cases, on break- 

 ing a rock to pieces with smart blows of the hammer. Ko fossils were 

 observed. Indeed, the lower portion of this rock is almost devoid of 

 organic remains. 



While making these observations, parties were engaged in boring 

 an artesian well, two miles above Cleveland. Prospecting for petro- 

 leum and coal was the object of the boring. Any practical geologist 

 could have told the proprietors that their hopes would not be realized, 

 and that their labor and money was being foolishly expended. In con- 

 nection, however, with th'e geology of this part of the county, they made 

 an interesting hole in the ground, of which the following is the best 

 section I could obtain. 



Section of Artesian well near Cleveland. 



1. Black earth, alluvial deposit 12 feet. 



2. Black and dark colored shales and slate 18 " 



3. Dark limestone, cap rock of Cleveland coal 3 ' ' 



4. Limestone (probably Hamilton and Xiagara) 398 ' ' 



5. Soft shale (probably Cincinnati group) 77 " 



At this depth the drill struck a sharp, hard rock, with sandy grit in 

 it. How much deeper this well was put down I have not ascertained. 

 Another artesian well was put down, just north of Kewanee, to a depth 

 of six hundred feet, in search of water, I believe. Xo accurate record 

 of strata bored through was kept. Three hin.:hvd and fifty or four hun- 

 dred feet of the bottom penetrated a hard light-colored limestone, being 

 perhaps the same formations passed through in the lower part of the 

 Cleveland well. This, however, is only conjecture. 



Coal Me as u res. 



With the exception of the formations just described, the whole county 

 is underlaid, below the usual drift deposits, by the low r er Coal Measures. 

 It is quite difficult to obtain a correct knowledge of the local extent of 



