60 GEOLOGY OF ILLINOIS. 



the creek for some distance, and would probably make a durable building stone. 

 There are but few counties in this State where good building stone is so abund- 

 ant, and easily accessible to all parts of the county, as here. 



Limestone for Lime. Most of the limestone used in the manufacture of 

 quick lime, is obtained from the Burlington limestone, in the vicinity of 

 Quincy, and a large amount of this article is produced annually for the supply 

 of the city and the adjacent country. The light gray beds of the Burlington, 

 and the bluish gray strata of the Keokuk group, are either of them sufficiently 

 free from silicious, or other foreign material, when carefully selected, to pro- 

 duce a quick lime of excellent quality. The upper or concretionary bed of the 

 St. Louis group is also, at many localities, a very pure carbonate of lime, and 

 may be found useful for this purpose in the eastern portion of the county, 

 where the underlying formations are not accessible. Its outcrop is mainly 

 around the borders of the coal formation, immediately below the sandstone 

 conglomerate which usually forms the base of the coal series. 



Fire and Potter's Clays. The under clays of coal seams No. 1 and 2, are 

 usually of good quality, and where the strata are of sufficient thickness, they 

 become valuable deposits of fire clay, and may be successfully worked in con. 

 nection with the coal seams. At some points, there is a bed of fine, light blue 

 clay shale, intervening between these two coal seams, which, on exposure, 

 weathers to a fine plastic clay, and forms an excellent potter's clay. This is 

 the bed from which the clays used in the potteries at Ripley, in Brown county, 

 have been obtained. This bed of clay shale is exposed at various points in 

 this county, and will furnish an abundant supply of potter's clay, while the 

 under clay 6f No. 2 may be used for the manufacture of fire brick. 



Clay and Sand for Brick. The sub-soil clays of this county, intermingled 

 with the fine sand of the Loess, forms an excellent material for the manu- 

 facture of common brick, and may be obtained almost anywhere in the 

 western part of the county, and there are but few points in the State that 

 have produced as good an article of common brick, as has been manufactured 

 for many years in the vicinity of Quincy. In the eastern part of the county, 

 where the Loess is wanting, the sand for this purpose may be readily obtained 

 in the alluvial valleys of the small streams. These materials are so universally 

 abundant, that almost every farmer in the county may find them at hand upon 

 his own premises, for the manufacture of all the brick required for building 

 purposes. 



Soil and Timber. As an agricultural region, this county is not surpassed by 

 any other portion of the State of the same geographical area. The western 

 portion of the county, including a belt of country from five to ten miles in 

 width, adjacent to the river bluffs, and extending through its entire length, 

 from north to south, is underlaid by the marly sands and clays of the Loess, 



