CHAPTER I. 



GOAL MEASURES. 



The coal area within the boundaries of the State of Illinois may he 

 safely estimated, in round numbers, at about 35,000 square miles, an area 

 nearly three times as great as that of Pennsylvania or Ohio, and equal 

 to one- fifth of the productive coal fields of the United States, throwing 

 out of the account the lignite basins of the western Territories. A line 

 drawn from Hampton, in Eock Island county, to the junction of the 

 Kankakee and Iroquois rivers, would define approximately the northern 

 line of the Illinois coal field ; but from the junction of these streams the 

 boundary line deflects south to the vicinity of Chatsworth, in Livingston 

 county, and thence eastwardly to the Indiana line. All the area south of 

 the line above designated, except a narrow belt along the Mississippi 

 to the mouth of the Ohio, and up the latter stream to Battery Eock, is 

 underlaid by the Coal Measures, and nearly all the counties within the 

 above described boundary have afforded some coal, although in several 

 of them the coal lies too deep below the surface to be available without 

 a heavier expenditure of capital than the present demand for fuel 

 would seem to warrant. 



The Coal Measures attain an aggregate thickness of about fourteen 

 hundred feet, and may be properly divided into upper and lower meas- 

 ures, taking as a line of demarcation the limestone of Shoal creek and 

 Carlinville, a tough brownish-gray rock that is so persistent in its litho- 

 logical characters and development as to make it a conspicuous horizon 

 in tracing the detailed stratification of the Coal Measures. This lime- 

 stone overlays a thin coal often only three or four inches in thickness, 

 but locally becoming from eighteen inches to two feet or more, as in the 

 vicinity of Highland, in Madison county, where it has been worked in 

 a limited way for many years. Above this limestone there is some 

 seven hundred feet of strata belonging to the upper measures, inclos- 

 ing six or seven seams of coal that range in thickuess from six inches 

 to three feet, but none of them attaining to the thickness of those in 

 the lower measures. In Europe a coal seam eleven or twelve inches thick 

 is considered of sufficient value to be worked in the usual way by 



