GEOLOGY OF ILLINOIS. 



At Grisw old's mines, cm the north-west quarter of section 24, township 

 8 north, range 7 west, coal No. 4 is from four feet to four feet six inches 

 in thickness, with the same kind of a roof as at Treasure's mines, and 

 the coal is similar in quality. 



No. 6 has been opened at many points in this vicinity, but from its 

 uneven development and its greater elevation above the creek valley, 

 it is not mined as systematically as the lower seam. The sandstone No. 

 6 of the above section is well developed along the Kickapoo bluifs in 

 this vicinity, and some extensive quarries have been opened here. The 

 rock is partly a brown micaceous, and partly a ferruginous sandstone, 

 in massive layers from one to three feet in thickness. The ferruginous 

 layers become .quite hard on exposure, and will no doubt resist the dis- 

 integrating influences of the atmosphere more effectually than any other 

 portions of the bed, but if carefully selected and the soft and shelly por- 

 tions of the rock rejected at the quarry, the remaining portion will no 

 doubt sustain a good reputation as a reliable building stone. 



On a ravine about half a mile west of Monroe's mill, coal No. 7 was 

 found high up in the hill. It is here only about eighteen inches in thick- 

 ness, and is separated from No. by about thirty-five feet of sandy and 

 argillaceous shales. It was overlaid by bituminous shale and a soft mi- 

 caceous sandstone. 



At Edwards' station, on the Peoria branch of the Chicago, Burlington 

 and Quincy railroad, coal No. 4 is some sixty feet below the level of the 

 valley, and No. 6 is worked by a horizontal tunnel into the base of the 

 hill just above the railroad grade. As at the outcrops of this seam fur- 

 ther west, it is quite variable in thickness here, ranging from three to 

 five feet, and, in consequence, it cannot be mined as cheaply as No. 4. 



About a mile south of Elmwood, coal No. 6 is reached by a shaft fifty 

 feet in depth. The coal is four feet to four feet and a-half in thickness, 

 with a few inches of bituminous shale, and a light-gray sandstone form- 

 ing the roof. The coal is tolerably soft, light and free burning, and 

 generally free from pyrite. Coal No. 7 outcrops in this vicinity and has 

 been worked in a limited way, but is too thin to be mined successfully 

 in competition with the lower seams. A boring near Elmwood, on the 

 south side of the Kickapoo, struck the bed rock at sixty feet and below 

 the horizon of coal No. 6, and was carried down through the following 

 strata : 



No. 1. Drift clay 60 feet. 



No. 2. Clay shale 18 



No. 3. Limestone 2 



No. 4. Bituminous shale 3 



No. 5. Coal. (No. 4) 3J 



No. 6. Sandy shale 15 



No. 7. Septeria .. 7 



