198 GEOLOGY OF ILLINOIS. 



FEET. 



Boulder clay 8 



Ferruginous sandstone * 1 



Shale 20 



S h;ily sandstone 19 



Shale, filled with fossil ferns 12 



Coal 3 



Soft slaty coal 1 



Fire clay 3 



In the north part of township 33 north, range 6 east, the shaly sandstones, 

 overlying this seam, are exposed in the bottom of every little run which cuts 

 away the soil from the edge of the second terrace, and fragments of them are 

 found scattered just below the surface over the whole lower flat. 



It has long been a favorite theory with miners that another seam of coal 

 could be found, by sinking shafts in the bottom of the present working. This 

 is not impossible, at points farther from the outcrop ; but at Morris, and to the 

 eastward, the coal lies directly upon Lower Silurian rocks, with only four or 

 five feet of fire clay to separate them. This is shown at several points. 



I had supposed that the seam had formerly extended, in its full thickness, 

 much further northward; but two wells, one in section 27, and the other in 

 section 13, township 34 north, range 7 east, after passing through the fossili- 

 ferous shales which overlie the coal, met with only about ten inches of soft 

 coaly shale, underlaid by a few inches of greenish clay shale, with small rounded 

 grains of calcareous (?) matter, (probably belonging to the Cincinnati group,) 

 which rested upon the solid limestones of the Trenton. The artesian boring of 

 Mr. Samuel Holderman, in the northeast quarter of section 3, township 33 

 north, range 8 east, after passing through forty-seven feet of the sandstone and 

 clay shales which, everywhere to the southward of that point, overlie the coal, 

 passed directly into a solid limestone which I can only refer to the Trenton 

 group. From these and similar facts, I am led to the conclusion that the pres- 

 ent line of workings corresponds very nearly with the original outline of de- 

 posit of the true coal seam, while beyond this line, only occasional small outly- 

 ing patches will ever be found, though thin layers of coaly shale may be met 

 with some miles further northward. On the AuSable creek, a few miles north 

 of the county line, small quantities of coaly shale and cannel coal have been 

 found, but they are probably of no practical value, and have no direct connec- 

 tion with the Morris seam. 



Upon the lower part of the AuSable, however, in the southeast quarter of 

 section 19, township 34 north, range 8 east, there is a peculiar outcrop of proba- 

 bly the lower seam. We have here a seam of coal twenty-eight inches thick? 

 with a floor of fire clay at least six feet thick, and a roof of black shale which 

 is, at the outcrop, quite solid and a foot thick ; but, at the shaft, perhaps fifty 



