MERCER COUNTY. 305 



tion, as but little of the strata above or below was exposed. The material for 

 the foundation of the jail at Aledo was taken from this locality. 



A little coal has been mined in sections 35 and 36, township 15, range 3. 

 The exposed strata here gave 



FT. IN FT. I N 



1. Clay shale. Not measured 



2. Sandstone, about 15 



3. Blue clay or clay shale 2 to 3 



4. Coal 1 6to 2 



5. Clay. Not measured 



There are extensive quarries in the sandstone, No. 2 of this section, in this 

 vicinity. Though soft when taken out, it hardens by exposure, and is light 

 colored and thick bedded. Much of the material for the walls of the Aledo 

 jail was taken from the quarries in section 35. 



The lower coal seam, No. 1 of the Illinois section, varies in thickness from 

 three to four feet, and it is from this seam that the principal part of the coal 

 for the supply of this region is obtained. From the mine in the southeast 

 quarter of section 1, township 14, range 3, the following section was obtained : 



FEET. IN. 



1. Impure, gray limestone 8 



2. Flinty limestone , 6 



3. Blue limestone 3 



4. Black slate 1 ft. 6 in. 2 



5. Coal 1 6 



6. Slate or shale 4 



7. Slaty coal 4 



8. Coal 1 8 



9. Sandy clay. Not measured 



A little farther west, the dividing slate in the upper coal was reported to be 

 four feet thick, and at a mine east of this, in section 6, township 14, range 2, 

 it is one foot and eight inches. Where it becomes so thick, the mining is ren- 

 dered very expensive, and these mines have been abandoned for the present. 

 In sections 3, 4, 5 and 6, township 14, range 2, this seam has been extensively 

 worked. A general idea of the position of the strata may be obtained from a 

 section made at the mines and quarries in section 4 : 



FEET. 



1. Impure, drab colored limestone 15 



2. Blue limestoae 2 



3. Coal 4 



4. Sandy clay. Not measured 



The shaly seam, mentioned above as dividing the coal into two parts, is only 

 found at a few mines, and is generally quite thin. The limestone, No. 1 of the 

 section, is extensively quarried in sections 3, 4 and 5. The rock is mostly in 

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