MERCER COUNTY. 303 



strata of limestone, sandstone, clay shale and coal, and attain a thickness of 

 from one hundred to one hundred and fifty, or possibly, in some places, two 

 hundred feet. There are three, perhaps four, seams of coal worked in this 

 county. 



The upper seam, No. 3 (?) of the Illinois section, has been found and worked 

 at but one point, sections 31 and 32, township 14. range 2. This seam is from 

 three to five feet thick, and the coal of good quality. From Mr. Martin's 

 shaft in the southwest quarter of section 32, and the exposed rocks in the 

 bluff below, the following section was obtained : 



FEET. IN. 



1. Drift. Not measured. 



2. White clay, sometimes sandy 7 



3. Limestone, impure 18 



4. Coal No. 3 (?) 3 to 5 



6. Sandstone, or sandy shale 10 " 15 



6. Slate, not always present 2 



7. Limestone 8 



8. Coal 1 foot 10 in. to 26 



9. Clay 4 



10. Slate, penetrated 16 



The limestone over the coal No. 4 of this section, contains numerous fossils, 

 among which are Hemipronites crenistria, Lima retifera, Productus Nebrascen- 

 sis, Conularia, and several species of Bryozoa. 



The second coal seam, No. 2 of the Illinois section, is, in this county, from 

 one and a-half to two and a-half feet thick. This seam has been found in quite 

 a number of places, but is, at present, worked at but two or three points. In 

 sections 20 and 21, township 13, range 2, it has been extensively minnd, 

 though but one mine, in section 20, is now in operation. The exposed strata 

 in this vicinity give the following section : 



FEET. IN. 



1. Coal, No. 3 (?), a trace. 



2. Sandstone, or sandy clay, about 15 



3. Limestone, impure and shaly 1 foot 2 in. to 14 



4. Blue arenaceous clay shale 6 in. " 1 



5. Coal, No. 2 2 feet " 2 6 



6. Blue clay, but partially exposed. 



The sandstone, No. 2 of this section, is light colored and soft, but hardens 

 on exposure. The quarries that are and may be opened at or near this locality, 

 will furnish an abundant supply of a fair article of building stone for the sup- 

 ply of the adjacent region. About two miles down North Henderson creek, in 

 the southwest quarter of section 1 9, there is an extensive quarry of sandstone 

 and conglomerate. This probably lies below coal No. 2, and near the base of 

 the Coal Measures. The sandstone is of fair quality, and can be had in blocks 

 of any desirable size, and, when first taken out, is soft and easily worked, but 



