CHAPTER I. 



ECONOMICAL GEOLOGY. 



Coal. The extensive area of the Illinois Coal Field, covering more 

 than thirty-six thousand square miles of territory within the bound- 

 aries of this State, is now under a process of rapid development, 

 and the liberal expenditure of capital and labor in this special field 

 of human industry during the last decade, has resulted in placing 

 Illinois as the second on the list of coal producing States of the 

 Union. No other mineral resource within our borders is at all com- 

 parable in intrinsic value with our coal deposits, and their complete 

 development is a subject of vital interest to the commonwealth, and 

 deserves to be encouraged by all legitimate means. 



The abundance of coal, the wide area over which it extends, and 

 the facility with which it can be mined, and the low price at which 

 it has been placed upon the market, has been a leading cause of 

 the great increase in our railroad facilities and manufacturing in- 

 dustries, thus adding vastly more than the intrinsic value of the 

 coal product alone, to the material wealth of our people. It has 

 enabled us to compete successfully with the water powers of New 

 England in the manufacture of our raw products, and thus saves the 

 cost of a double transportation to which our people were heretofore 

 subjected, in the transfer of our raw products to the eastern manu- 

 facturers, and the manufactured product back to the great food pro- 

 ducing centers of the Mississippi valley. 



In Eock Island county, where only the lower seam, or No. 1 of 

 the general section of the Illinois Coal Measures, is found thick 

 enough for profitable mining, and where it has been relied on for 

 the supply of the entire region north of the Rock Island rapids for 

 the last thirty years or more, the supply is now well nigh exhausted, 

 and the counties lying further east and south must now be resorted 

 to for the future supply of that region. Rock Island county lies on 

 the extreme northwestern borders of the coal field, and the Coal 



Measures there rest upon Devonian limestone, the whole of the 

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