36 ECONOMICAL GEOLOGY. 



had increased in thickness about 70 feet in a distance of about 

 half a mile, the increased depth being in a southerly direction. 

 This would indicate that Clinton is located near the northern 

 slope of this ancient valley. 



I am inclined to regard the 2 feet 9 inches coal reported in 

 this boring (No. 11) as probably the equivalent of the upper 

 workable seam in the Bloomington shaft, and also of that in 

 the shafts at Lincoln, Mt. Pulaski, and Decatur, and if so, it 

 is much thinner at Clinton than at the points above named. 

 Nos. 33 to 37 inclusive, represent a lower seam, that may be 

 equivalent to Nos. 2 or 3 of the general section, and No. 57 

 may be regarded as No. 1. 



After the publication of Vol. VII, the proprietors of the coal 

 shaft at Mattoou put down a boring with the diamond drill to 

 the depth of 203 feet, which probably reached the bottom of 

 the coal measures. 



For a detailed report of this boring, I am indebted to Walton 

 Rutledge, Esq. Commencing below the coal in the shaft, which 

 has been referred to coal seam No. 2 of the general section, the 

 details of the boring are as follows: 



Ft. In. 



1. Fire clay 15 



2. Gray shale 70 



3. Black slate 1 



4. Coal 1 8 



5. Fireclay 3 4 



6. Dark shale 4 



7. Coal 4 



8. Fireclay : 1 8 



9. Light shale 12 



10. Hard sand rock 4 



11. Sandy shale 27 



12. Dark shale 45 



13. Black slate 9 



14. Dark green shale 6 



15. Limestone 8 



Total thickness 203 



This, added to the 800 feet of coal measures passed through 

 in the shaft, gives a total of about one thousand feet, and rep- 

 resents probably about three-fourths of the entire thickness of 

 the coal measures in this State. Nos. 4 and 7 of the above 

 record represent probably coal No. 1, which is often a double 

 seam, and the limestone at the bottom belongs to the Lower 

 Carboniferous formation. 



