60 GEOLOGY OF ILLINOIS. 



and some other varieties of timber are more or less to be noticed, and 

 in some particular localities are found in considerable abundance. 



Such, in brief, are the topographical features of Stephenson county 

 a county whose agricultural resources are not surpassed by those of any 

 county in Northern Illinois. Indeed, it would be hard to find an equal 

 area anywhere in the State, whose soil is so universally good, produc- 

 tive and teeming in every bountiful gift to the industrious tillers of the 

 earth. No mineral wealth, or peculiar manufacturing facilities, will at- 

 tract to this county the attention of the adventurous ; but for those re- 

 sources which are derived from a rich soil and abundant agricultural 

 capabilities, this favored county may well claim a lasting pre-eminence. 



Geological Formations. 



The geology of Stephensou county is of a very simple character. 

 After leaving the surface geology, the first formation met in a descend- 

 ing order is the Niagara limestone, succeeded in regular order by the 

 Cincinnati shales, and the three divisions of the Trenton period, namely, 

 the Galena, Blue and Buff limestones of the old Trenton seas. The fol- 

 lowing section shows the actual, worked exposures of these rocks as 

 measured in the quarries by the writer of this article. In 110 instance, 

 perhaps, do the measurements exhibit the maximum thickness of the 

 formations. At some points where measurements were made, the rocks 

 of the formations measured undoubtedly extended downwards to an in- 

 definite extent, and in the few particular instances where the bottom of 

 a formation was distinctly identified, denuding agencies had carried 

 away much of the superincumbent mass. A section thus constructed 

 might be styled a surface section of the formations indicated, and in a 

 level country, where no borings had been made, would be the only at- 

 tainable one to be had. 



Section of worked outcrops. 



Quaternary deposits, consisting of clays, sands, gravels, surface soils, etc 10 to 65 feet. 



Niagara limestone 23 



Cincinnati group 40 



Galena limestone 75 



Blue limestone : 38 



Butf limestone 40 



Each of these groups or formations outcrops at some place or places 

 in the county. Some of them are the immediate underlying rocks over 

 large portions of the same. 



As further illustrating the geological formations of this county, and 

 more especially those which lie deep down in the earth, we now give an 

 imperfect section, obtained from the borings of the rocky farm oil well. 

 This well was commenced, we believe, in 1864, and continued on through 



