42 GEOLOGY OF ILLINOIS. 



The eight inch coal in the above section is below that mentioned on 

 a previous page as occurring on Mr. Henderson's place in this negh- 

 borhood, as that is found from 25 to 30 feet or more above the bed of 

 Indian creek, and ranges from twelve to eighteen inches in thickness. 

 The following is an approximate section of the rocks outcropping in 

 this county : 



Feet. 



Brown and gray sandstone, the lower part in massive beds CO to 75 



Coal— No. 12 - 1 to H 



Shale, with bands of argillaceous iron ore 30 to 35 



Coal— No. 11 to 1 



Sandstone, top tbin-bedded and sbaly, bottom massive 30 to 35 



The upper sandstone underlays the northern and western portions of 

 the county, and is penetrated in sinking wells nearly everywhere upon 

 the uplands. At its base there is usually a very hard stratum that is 

 sometimes called limestone on account of its hardness, and also a ferru- 

 ginous bed, that passes locally into a sandy iron ore. The lower sand- 

 stone forms the main portion of the Wabash bluff at St. Fraucisville, 

 and also appears at the Shaker mill on the Embarras ; but its outcrop 

 is restricted to the eastern border of the county. 



Economical Geology . 



Building stone. — Both the sandstones in the foregoing section afford 

 more or less building stone of fair quality for ordinary use, and exten- 

 sive quarries have been opened in the upper one in the. vicinity of 

 Sumner for the use of the O. & M. Railroad. Small quarries have been 

 opened in various places in the central and northern portions of the 

 county in this bed to supply the local demand for foundation stone, 

 walling wells, bridge abutments, etc. Leeds' stone quarry on Indian 

 creek, south of Lawrenceville, and one mile west of the St. Francisville 

 road, is probably in the lower bed of saudstone, and the rock obtained 

 there is in thin, even beds, ranging from four inches to a foot in thick- 

 ness. 



The limestone associated with coal No. 11 at Lawrenceville, and at the 

 bridge two miles east on the Embarras, is somewhat argillaceous, and 

 consequently cannot be depended on where it is to be subjected to the 

 action of frost and moisture, although it has been used in building the 

 Lawrenceville bridge. This is the only limestone that was met with in 

 the county, and being both argillaceous and silicious, it is not adapted 

 either for building purposes or for the lime kiln. 



Coal. — The uppermost of the two coal seams, that outcrop in this 

 county has been worked in a small way at several points by stripping, 

 and affords a coal of very good quality; but unfortunately it has been 

 nowhere found thick enough to be profitably mined in any other way. 



