288 GEOLOGY OF ILLINOIS. 



Feet. In. 



No. lf>, Soft limestone or calcareous shale 



No. 17. Bituminous shale 



No. 18. CoalNo.8 - 10 



No. 19. Sandstone and sandy shale "2 



No. 20. Shales with ironstone 



No. 21. Hard calcareous (?) sandstone 



No. 22. Blue claj- shale 



No. 23. Variegated shales (Horizon of coal No. 7) 22 6 



No. 24. Sandy shales - - - 26 



No. 25. Soft bituminous shale 



No. 26. Limestone 



No. 27. Bituminous shale 2 6 



No. 28. Coal No. 6 , 



No. 29. Fire-clay / .. 



No. 30. Sandstone. f - 4 



No. 31. Coal No. 6 ) .- -- 1 6 



No. 32. Fire-clay 



No. 33. Sandstone and shale - - 10 



No. 34. Limestone 7 



No. 35. Bituminous shale 6 



No. 36. CoalNo.5 -7 * 



Total depth to the bottom of the coal 320 1 



A shaft has also been sunk at Girard down to this main coal, but as no 

 record was kept of the thickness and character of the beds passed 

 through, we are unable to designate the changes which mark the various 

 strata between these points. 



The coal worked at these shafts, as well as all others at present in 

 operation in this county, is, in my opinion, No. 5 of the general section 

 of the Coal Measures of Western Illinois, as given in the third and 

 fourth volumes of these reports. In the central portions of the county- 

 its thickness ranges from six to eight feet, but on Apple creek, in the 

 north-west corner of the county, a coal outcrops that seems to be the 

 equivalent of this, but is much thinner, ranging only fro:n two to three 

 feet, and at Howard's shaft, one mile and a half north of Bunker Hill, 

 its average thickness is about four feet. 



At the Virden shaft the main coal (No. 36 of this section) averages 

 about seven feet and a half in thickness, sometimes running tip to eight 

 feet, and seldom falling below seven. It is a moderately soft, free burn- 

 ing coal, especially that from the upper portion of the seam, from two 

 to three feet in thickness, which is an excellent smith's coal. The seam 

 is divided by a shaly parting of about an inch in thickness, which is 

 very persistent, and about one-third the distance from the bottom to the 

 top of the seam. The coal has a tendency to break into cubic blocks 

 like the Belleville coal, though the partings which separate the coal into 

 several distinct layers are not as decided here, as at the mines in St. 

 Clair and Randolph counties. No horsebacks or other impediments 

 to the profitable working of this coal has yet been encountered in this 

 shaft. Salt water in small quantities percolates through some of the 



