296 GEOLOGY OF ILLINOIS. 



Ouemile and a half south-east of Cummiugton the Carlinville limestone 

 outcrops on the breaks of the small streams, and only from thirty to forty 

 feet below the general level of the prairie. It was also found on section 

 7 in the same township, where it was underlaid by eighteen inches of 

 bituminous slate and shale, representing the horizon of No. 9 coal, and 

 by about fifteen feet of sandy shale and sandstone. 



The lowest strata exposed in this county are on Apple creek in the 

 north-west corner, and on Hodge's creek in town 10 south, range 9 west, 

 near the Greene county line. At the locality last named coal No. 5 crops 

 out in the bluffs of Hodge's creek, and has been mined to supply the 

 local demand for coal in that vicinity ever since the first settlement of 

 this part of the county. 



At Thomas Bielby's' mines, in the bluffs of Hodge's creek, on section 

 29, town 10 north, range 9 west, the coal ranges from five to seven feet in 

 thickness, and is overlaid by from one to three feet of black shale, forming 

 a good roof. A half mile further south, on a small branch of the creek, 

 the coal is overlaid by a foot or more of black shale, then follows eight 

 to ten feet of "hard steel-gray limestone, with intercalations of calca- 

 reous shales. Above this is a bed of clay shale, and a second limestone 

 of a lighter color, but weathering to a rusty-brown, and filled with 

 Fu#ulina; which would seem to identify it with the limestone usually 

 overlaying coal No. 6. The section here is as follows : 



No. 1 Yellow shale, with thin plates of limestone 4 to 6 feet. 



No. 2. Yellowish- grfty limestone, with Fwntlina. . . 4 ' 



No. 3. Green shales partly bituminous 6 to 8 ' 



No. 4. Steel-gray limestone and calc. shale 8 to 10 " 



No. 5. Blackshale 1 to 2 " 



No. 6. CoalNo.52 5 to 7 ' 



I am inclined to the opinion that in the shales and limestone forming 

 Nos. 2 and 3 of the section we have a representation of coal No. 6 and 

 its overlaying limestone ; and at Mr. Davis' coal bank, about a mile 

 west by south from this locality, the coal is directly overlaid by about 

 two feet of light-gray fire-clay, above which there was about two feet of 

 yellowish-gray limestone similar to No. 1 of the above section, which led 

 me to suspect the coal here to be a local development of No. 6. The 

 lowest bed of the foregoing section is undoubtedly the same coal worked 

 in the shafts at Virden, Girard and Carlinville, though the coal con- 

 tains more pyrite (or sulphur as the miners term it) here, on its outcrop, 

 than in the shafts above named, where it lies from three to four hundred 

 feet below the surface. The coal varies however in this respect in the 

 different mines in this county, and indeed in different portions of the 

 same mines, this sulphurous compound being more abundant at some 

 points than others. 



At or near the old strip banks on Hodge's creek, coal No. 4 outcrops 



