SANKAMON COUNTY. 3Q9 



Stratified Rocks . 



The stratified rocks outcropping at the surface in this county all 

 belong to the upper Coal Measures, and overlie all the main coal seams 

 worked in the State. The lowest beds exposed in the county are found 

 on the Sangaiuon river, near the Meuard county line, and on Richlaud 

 rirek, one of the southern affluents of the Sangamon, in the western 

 part of the county. They consist mainly of sandstones and shales, 

 including the horizon of the Rock creek limestone, although we have 

 not as yet seen any outcrop of this limestone in Sangamon county. 



A vertical section of all the beds exposed on the Sangamon and its 

 tributaries, in the central and western portions of the county, would 

 show the following relative position and thickness of strata : 



So. 1. Sandy shales and soft sandstones 15 to 20 feet. 



So. 2. Hard, gray limestone, partly brecciated 10 to 12 " 



So. 3. Black, slaty shale 2 to 3 " 



Xo. 4. Claysliale 4 to 6 " 



X". 5. Brown, calcareous sandstone, passing into a ferruginous limestone 4 to 5 " 



X<>. 6. Clay shale, partly bituminous 4 to 6 " 



So. 7. Hard, gray limestone (Carlinville limestone) 6 to 8 " 



So. S. Sandy shales and soft sandstone 30 to 40 " 



No. 9. Argillaceous limestone and calcareous shales. 2 to 3 " 



So. 10. Bituminous shale 1 " 



So. 11. CoalXo.i< 1 to 2 " 



So. 1-2. Fireclay * '2 to 3 " 



No. 13. Impure limestone (local) .- 4 to 6 " 



Xo. 14. Sandy shales and soft sandstones, with local bands of argillaceous and bitumin- 

 ous shales - 50 to 60 " 



Xo. 15. Hard, gray limestone 2 to 6 " 



So. 16. Shales sandy, argillaceous and bituminous, with a thin seam of coal 30 to 40 " 



The beds numbered from one to seven inclusive, of the above section, 

 are well exposed on Sugar creek two miles north of Virden, and thence 

 down the creek to the crossing of the St. Louis, Alton and Chicago rail- 

 road, between which points all the beds included in these numbers out- 

 crop in succession, the eastward dip of the strata being somewhat less 

 than the fall of the stream. The upper limestone, Xo. 2 of the above 

 ion. is well exposed near the bridge on the main road north of Virden, 

 and lias been quarried both for lime and for building stone. The upper 

 part of the bed is a nodular, unevenly bedded rock, partly brecciated, 

 while the lower portion is more evenly bedded, affording a tolerably good 

 building stone, in layers from four inches to a foot or more in thickii 

 A little farther up the creek, the whole mass becomes brecciated and 

 fragmentary, and quarries in pebbly fragments suitable for macadami- 

 zing material. The brown ferruginous bed Xo. 5 of the foregoing 

 <>n is a hard massive rock, resembling the limestone at Crow's mill, 

 on Sugar -m-k six miles south of Springfield, of which it is probably the 



