286 GEOLOGY OF ILLINOIS. 



Economical Geology. 



Building Stone. Henderson county has an abundant, though not evenly 

 distributed, supply of building stone. The Burlington limestone, which out- 

 crops nearly from one end of the county to the other, along the bluffs of the 

 Mississippi, and also on the larger streams, will afford much the greater part 

 of this supply. The rock is principally a light colored, massive, crinoidal lime- 

 stone, which is but little affected by the weather. The prevailing color is a 

 light bluish or yellowish gray. In some localities, a portion of the strata con- 

 tains considerable oxyd of iron, which gives the stone a much darker brownish 

 color. It is tolerably even bedded, in strata from six inches to two feet or 

 more in thickness, and can be easily and cheaply quarried. A few good farm- 

 houses have already been built in this county from this material, and, as wealth 

 increases, it will probably come into more general use as a building stone. 



The Burlington beds have been most extensively worked in the eastern part 

 of the county, especially on Ellison creek and its branches, and near Sagetown. 

 Of the quarries near the latter place, the most important are those of A. Wall- 

 baum, Esq. The s e have been opened about eight years, and at present are ex- 

 tensively worked, a large number of hands being employed. Many of the cul- 

 verts and the abutments of the bridges of the Chicago, Burlington and Quincy 

 railroad are built of material obtained here. Large quantities of rock are now 

 quarried here, and sent out of the county by this railroad. 



The Keoku's limestone furnishes the balance of the building stone for this 

 county. It is generally even textured, dresses well, and affords strata suf- 

 ficiently thick for all the ordinary purposes for which building stone is required. 

 It is exposed in the southwest part of the county, where it has been worked to 

 some extent, but the strata rise to the north, and soon run out, and are not 

 again visible till just north of Ellison creek, in township 9, range 4. Its 

 greatest exposure is at and near Biggsville. Just west of town, in the bluffs 

 of the south Henderson, there is a partial exposure of these beds of from 

 twenty-five to thirty feet in thickness, a section of which has already been given. 



Limestone for Lime. The largest supply, and the best material for the 

 manufacture of quicklim3, is furnished by the limestone beds of the Burlington 

 group. At nearly all the exposures, rock suitable for this purpose can be had. 

 The light colored layers are nearly a pure carbonate of lime. At some locali- 

 ties, the quality of the rock is much injured by the quantity of chcrty nodules 

 present, which have to be removed before it is burned. The beds of the Keo- 

 kuk also furnish considerable material for this purpose, which, when carefully 

 selected, make good lime. The supply of stone, both for building and for 

 lime, is inexhaustible. 



The cherty nodules, so common in both the Keokuk and Burlington beds, 



