58 GEOLOGY OF ILLINOIS. 



calcareous shales and magnesian limestones. The bed of silicious limestone 

 near the base of the above section, may represent the light blue, or dove col- 

 ored limestone, called in the Missouri Report, " Lithographic Limestone," but 

 at this locality, it appears more like a stratified flint than anything else. Fos- 

 sils are quite abundant in the silicious gritstones at Kinderhook, and several 

 points in Pike county, but none were found at the exposures on Fall creek. 

 The outcrop of this formation in Adams county, is restricted to the vicinity of 

 the river bluffs, from this creek to the south line of the county. 



Economical Geology* 



Bituminous Coal. About one-half of the entire area of Adams county is 

 underlaid by the Coal Measures, embracing the central and eastern portions of 

 the county, and the strata developed here, include the three lower coal 

 seams, and the beds usually associated with them, but the coal seams, except 

 the middle one, are very irregular in their development, and therefore be- 

 come of little value for the production of coal. The middle seam, or No. 2, 

 the equivalent of the Colchester coal in McDonough county, is generally quite 

 regular in its development, and will be found underlying most of the region 

 north and east of Columbus. Its average thickness is a little over two feet, 

 though it frequently attains to thirty inches, and sometimes to three feet. The 

 coal it affords is of a fair quality, and in some respects, above the average of 

 our western coals. The analysis of Bassett's coal, given on a preceding page, 

 will serve to indicate the quality of the coal obtained from the southern part 

 of the county, and may be compared with the following analysis of Higby's 

 coal, two miles north of Mendon, which I believe to be an outlier of coal 

 No. 1. This analysis was made by the late Mr. Henry Pratten, and is given 

 in Norwood's "Analysis of Illinois Coals" : 



Specific gravity 1.3354 



Loss in coking 48.4 



Total weight of coke 51.6 



100.00 



Analysis: Moisture 10.0 



Volatile matters 38.4 



Carbon in coke 41.2 



Ashes (yellow) 10.4 



100.00 



Carbon in coal 48.0 



This is a heavier coal than that from No. 2, and contains about seven per 

 cent, less of fixed carbon, according to the analysis here given. The coals 

 from Nos. 1 and 3, are usually inferior in quality to that obtained from No. 2, 

 and the two former are not likely to be found sufficiently persistent in their de- 

 velopment in this county, to be of any great economical value for the produc- 



