256 GEOLOGY OF ILLINOIS. 



feet, in all that portion of the county west of a line passing north and south 

 through Danville, and south of the north line of township 19 north, with the 

 exception of about one section in the northwest corner of township 19 north, 

 range 11 west. Both seams are constantly present along the entire outcrop, 

 and there is reason to believe that both will be found of workable thickness at 

 all points where their level shall be reached in the county. 



The upper seam is largely worked at and near Danville, both in shafts and 

 sbrippings. At this point it has more than twice the thickness of the lower 

 seam, and is accordingly made a source of supply, although of inferior quality. 

 This fact, together with the carelessness of the miners, in not duly separating 

 the slaty and pyritous portions of the seam from the good coal, has tended to 

 impair the reputation of the coal of this county. As a fair estimate of the 

 character and value of the coal, I append the following letter from Maj. Joseph 

 Kirkland, now of Chicago, who has owned and worked coal mines in this re- 

 gion for many years : 



307 HURON STREET, CHICAGO, Dec. 25th, 1858. 



PROF. FRANK H. BRADLEY, Assistant Geologist of Illinois : 



MY DEAR SIR: The coal of the main Danville seam is a strong, fat, soft, caking coal ; aver- 

 ages six feet thick, lies nearly level, dipping say ten feet per mile toward the southwest ; is 

 hardest and most impure in its lowest stratum of eight inches or so ; purest and best in the 

 " blacksmith coal " stratum, one and a half to two feet next above, and more and more friable 

 as you near the roof. The seam contains probably quite as much sulphur as other Illinois coals, 

 but it is in masses, thick layers or nodules, easily separated and thrown out, and therefore less 

 of a detriment in use than would be a smaller proportion more intimately associated with the 

 body of the coal. The roof is generally not good in the workings so far explored. The coal 

 at all the mines (say six miles apart at farthest) is nearly equal in quality, though harder and 

 therefore better in proportion to its distance from surface and outcrop. Its money value in 

 general markets is about ten per cent, less than the best Illinois coal; and say fifty per cent, 

 less than the best bituminous coal mined in the country. 



There is no doubt as to the existence of two seams of coal at and near our workings. The 

 main one is that we are working, and is that I have described. The second is from one foot 

 to two or more in thickness, and is about sixteen feet below the upper, at our mine. You can 

 see it at many bluff exposures on the Vermilion ; also, in the well which supplies our mine en- 

 gine with water. The mooted point is the existence of a third seam reported, at say eighty feet 

 below the upper seam, by the traditions of the old salt works borings ; which legends also re- 

 port it to be sixteen feet in thickness. 



Some Geologists (Col. J. W. Foster, of Chicago, for example,) have concluded that there is 

 such a seam, and that it is identical with the " Grape Creek " coal, a development six miles 

 or so south of Danville, of a superior quality of coal. The Chicago and Carbon Coal compony 

 sunk an experimental well (under my superintendence), starting in the ravine at a point about 

 twenty feet below the working scam of coal (below the second seam) and prosecuted down 

 some eighty feet, finding no coal ; nothing but a continuation of the pale, sandy shale, hard 

 while in loco, but disintegrating on exposure. 



From the result of my observations and experience, and the absence of any known outcrop, 

 northeast of the outcrop of the main seam of Danville coal, I am disposed to conclude that 



