6 COAL MEASURES. 



Ft. In. 



No. 33. Blue shale 79 



No. 34. Coal 1 2 



No. 35. Clay shale 3 



No. 36. Lime conglomerate 8 



No. 37. Ligkt-co oreil shale 10 



No. 38. Sandstone 56 



No. 39. Dark shale 43 



No. 40. Black slate, with carbonate of iron 6 



No. 41. Coal H 



No. 42. Clay shale, with sulphuret of iron 3 



No. 43. Limestone, kidney ore aDd fire-clay mixed 11 



No. 44. Sandstone, with snlphuret of iron 1 



No. 45. Black slate 1 



No. 46. Fire clay 1 6 



No. 47. Gray limestone 2 



No. 48. Variegated shale 8 



No. 49. Coal 2 



No. 50. Limestone 3 



No. 51. Blue shale 2 



No. 52. Gray limestone 4 6 



No.53. Black shale 3 6 



No 54. Gray limestone 4 



No. 55. Black shale 12 



No. 5G. Blue limstoue 7 



No. 57. Bituminous shale 2 6$ 



No. 58. Coal 7 



Total depth 576 



No. 9 of this shaft corresponds with No. 47 of the general section, and 

 No. 23 is probably the Carlinville limestone, the equivalent of No. 45 

 of the general section. This shaft is nearer the center of the coal field 

 than any other in the State, and there seems to be a general increase 

 in the thickness of the strata from the borders of the coal field east- 

 wardly, which carries the lower seams to a greater depth from the 

 surface than they were supposed to be, judging only from the exami- 

 nations made at points remote from the center of the basin. In San- 

 gamon and Macoupin counties the main coal is found generally at a 

 depth of 200 to 240 feet below the Carlinville limestone, while at Cen- 

 tralia the first workable coal reached in their shaft was 373 feet below 

 this limestone, though it is quite possible that the coal found there 

 belongs to a lower horizon than the seams opened in the more northern 

 counties. The borings at Pana, Vandalia and Decatur have not 

 reached auy workable coal, so far as reported, though the one made at 

 the two former points was carried far enough to reach the Springfield 

 coal, unless there is a greater increase in the thickness of the overlay- 

 ing strata than could be reasonably anticipated. The boring with the 

 diamond drill at Decatur was stopped from 80 to 100 feet above the 

 horizon at which the coal should be found, and hence afforded no evi- 

 dence in regard to the development of the main coals in that county. 

 A single boring is, however, in no case a satisfactory test as to the 

 development of coal at a given point, as the drill might strike what the 



