242 GEOLOGY OF ILLINOIS. 



No. 12. Bituminons shale 3 to 5 feet. 



No. 13. Coal No. 4 4 to 4J " 



No. 14. Fire-clay with septaria 2 to 3 ' 



No. 15. Shales partially exposed to river level 20 " 



Previous to this time a boring was made here, no accurate record of 

 wlrich was kept, but a coal seam three feet thick was reported at a depth 

 of about one hundred and fifty feet below the lower seam in the above 

 section, and as that is about the depth at which So. 2 would probably 

 be found, the report is by no means improbable. From the careless 

 manner in which borings were made at this time, and the incompetency 

 of those most frequently placed in charge of this kind of work, but little 

 dependence should be put upon the reported results. 



At the Mapleton mines, the first now in operation north of Kingston, 

 the coal in No. 4 is somewhat thicker than its general average in this 

 county, being, according to the report of the mining engineer, from five 

 feet to five feet ten inches in thickness. This seam is also less subject 

 to interruption from "horsebacks" here, than in some of the mines fur- 

 ther north, and where they do occur they are usually of limited extent. 

 These mines have been opened in the most substantial way, the entries 

 are spacious and thoroughly secured with heavy timbers, and the work 

 is prosecuted in the most thorough manner. 



At the Orchard and Hollis mines, opposite the city of Pekin, the 

 same seam is worked, and the coal is from four feet to four feet ten 

 inches thick with a very good roof of bituminous shale. A "horseback" 

 has been encountered in these mines, so extensive, as to lead some of 

 the miners to the conclusion that a true fault or dislocation of the strata 

 occurred here, but from such examinations as I was able to make, both 

 in the mines and the adjacent ravines, where conclusive evidence of a 

 fault ought to be apparent if one existed, I came to the decided con- 

 clusion that no dislocation of the strata had taken place, but that the 

 coal had perhaps been cut away by the action of water currents, and 

 the clay deposited in its place, and that when it was found on the other 

 side of this so-called "fault" it would be found at about the same level 

 with the coal now worked in the mine. On one of the ravines immedi- 

 ately west of these mines, we were shown a locality where the rocks had 

 apparently been partially undermined by the erosive agencies that formed 

 the valley, and the strata of sandstone and shale above the coal having 

 partially fallen, dipped to the eastward at a high angle, and this was 

 regarded by some as conclusive evidence of the occurence of a fault in 

 this vicinity. But if this was the case, and this apparent dip continued 

 to the Orchard mines, it would carry the coal seam far below its present 

 level, and probably even below the level of the Illinois river, while on 

 the contrary the coal in these mines lies nearly horizontal, and is, more- 

 over, on about the same level as in the mines on either side. Hence we 



