180 GEOLOGY OF ILLINOIS. 



No fossils were observed in and about these coal mines, except sections 

 of a flattened coal plant of some kind, found in the roof slates of the 

 upper seam. These fragments had become completely impregnated with 

 sulphuret of iron ; they presented a beautiful iridescent appearance, and 

 readily split with the grain of the plant, showing its fibrous texture. 



The next important coal mines are at Bierman's shaft, five miles east 

 of Princeton, on section 17, in the township of Selby. Two seams are 

 reached here. The following section will give an idea of this coal de- 

 posit. 



Sectional Bierman's Shaft. 



1. Usual oak land soil and sub-soil 4 feet. 



2. Yellow, hard, ringing sandstone 10 



3. Soapstone, clay, shale and other deposits fi4 



4. Coal soft, rusty, inferior, No. 7 2J 



5. Black shale, clay and sandstone 42 



6. Coal hard, bright, good quality, !No 6 5 



The upper sandstone in the above section outcrops along the banks of 

 the creek a few hundred yards below this shaft. This coal seam dips 

 apparently towards the north-west. The shaft is operated by a common 

 two-horse whim. The mine is a very valuable one, and it will pay to 

 put on a steam engine and work it strongly. Another shaft, being sunk 

 a short distance down the creek, had passed through the upper seam, 

 and had reached the lower sandstone at the time I was there. Th> de- 

 posit, I think, is of considerable local extent, and ought to be more fully 

 prospected. The coal is of excellent quality, fully equal to the Shef- 

 field coal. The seams, I think, are identical. The drifts from Bierman's 

 shaft run north and east a few hundred yards. Like 1he upper Peru 

 seam, tuis is frequently interrupted by faults, clay slides and horse 

 backs. These latter are places where the coal gives out for short dis- 

 tances, and is replaced by boulders, nodules, shales and a conglomerate 

 mass of sulphuret of iron. The mines at Coal Valley, in Eock Island 

 county, at Perry's, in Henry, at Tiskilwa and Sheffield in this county, 

 and the upper workings at LaSalle and Peru, all, more or less, have 

 this characteristic feature, but are not therefore necessarily the same 

 coals. 



These are the only localities in the county where coal is worked to 

 any extent. There is said to be a thin outcrop of coal on Nigger creek, 

 among the Illinois river bluffs. This would be a few miles east of Bier- 

 man's shaft. If coal does exist there, it has as yet attracted no atten- 

 tion. There are several other localities in the county where coal is sup- 

 posed to exist, but they are not worked, and have not even been tho- 

 roughly prospected. 



The position to which these seams should be assigned in the general 

 section of the coals of Northern Illinois is not so easily fixed. The 



