264 GEOLOGY OF ILLINOIS. 



evenly. At Stewart's quarries, two miles west of Macomb, there is 

 about twelve feet in thickness exposed in the face of the quarry. The 

 rock is a rather coarse-grained sandstone, nearly white in color, and 

 furnishes a very durable material for foundation walls, and is also easily 

 cut and may be advantageously used for all ordinary architectural pur- 

 poses. 



At these quarries the rock is very massive, but at the old McLean 

 quarries, about half a mile to the westward of Stewart's, the sand- 

 stone is more regularly bedded, the layers varying from four to twelve 

 inches or more in thickness. This sandstone is the equivalent of that on 

 theT.,P. and W. Railroad west of Seaville, in Fulton county, and is very 

 similar in quality. Some of the beds seem to be sufficiently even-tex- 

 tured for grindstones. The inagnesian and arenaceous beds of the St. 

 Louis group will afford the best material for culverts and bridge abut- 

 ments that can be found in the State, as they are scarcely at all affected 

 by the action of frost and moisture. The gray limestones of the Keokuk 

 series make a durable building stone if protected from water, but split 

 to fragments on exposure to ordinary atmospheric agencies. The brec- 

 ciated limestone will make an excellent macadamizing material for 

 the construction of turnpike roads, or for ballasting our railroads. 



Limestone for Lime. Good limestone for burning into quicklime may 

 be obtained from the lower division of the Keokuk, and from the brec- 

 ciated bed of the St. Louis group. Where the former is used, it should 

 be selected with some care, as a portion of the beds contain too large a 

 per cent, of argillaceous or silicious matter to slack readily when burned, 

 and would yield only an inferior quality of lime. The light-gray, semi- 

 crystalline layers are the best for this purpose, and will make a quick- 

 lime of good quality. The brecciated limestone is, however, in many 

 respects, the best rock in the county for this purpose, as it is usually a 

 nearly pure carbonate of lime in its composition, and can be burned at 

 less expense and makes a quicklime of superior quality. This limestone 

 may be found on most of the tributaries of Crooked creek, and on the 

 east fork as far north as the vicinity of Colchester. 



Sand and Clay for Brick. The subsoil, where it is predicated upon 

 the marly beds of the loess, supplies these materials in nearly the right 

 proportion for the brick yard; and when deficient in sand, this may )><> 

 easily supplied either from the creek bottoms or sandy beds interstrati- 

 fied with the drift clays. These materials are so universally distributed 

 that there is scarcely a neighborhood in the county where they may not 

 be read^y found at hand. 



Soil and Agriculture. There is not much variety in the general char- 

 acter of the soils in this county, and there is no considerable portion of 

 its surface that will not bring good crops of the various cereals usually 



