DEKALB, KANE AND DUPAGE COUNTIES. 123 



Passing up the creek, we find again in the southeast quarter of section 42, 

 similar ledges of brownish-yellow and buff colored limestone appearing to the 

 hight of about six feet, on the north bank of the creek. Fossils were numer- 

 ous at this place also, but were similar in condition to those in the locality pre- 

 viously described. One and a half miles farther east, in the western part of 

 section 2, township 42, range 4, is another exposure, at which also the rock has 

 been somewhat quarried. The limestone is worked right at the water's edge, 

 and is said to appear also in the bed of the stream in this vicinity. The upper 

 beds here are friable and thin ; the lower beds, however, are said to answer well 

 as a building material for the rougher kinds of work. 



Economical Geology. 



Building Stone. The best stone for general building purposes which is found 

 in this district, is that which is obtained from the quarries at Batavia and the 

 southern part of the city of Aurora. This is apparently near the top of the 

 Niagara group, as it is developed along the Fox river, though probably within 

 one hundred feet from the base and actually in the lower part of the formation. 

 It is probably in about the same geological horizon as the well known Joliet 

 stone, which it very much resembles. It is here a light gray or drab, evenly 

 bedded limestone, the beds varying from eight inches or lessee nearly three 

 feet in thickness, affording blocks of all sizes required for building purposes. 

 The stone dresses well, is strong and durable, and after being cut is of an agree- 

 able light drab or buff color, which, .however, is liable to be considerably deep- 

 ened by the action of the weather. Occasionally, also, some layers of the stone 

 contain nodules of pyrites which, decomposing, leave unsightly stains on the 

 walls and buildings in which it is used, as may be observed, for instance, in the 

 court house at Geneva. This stone is used extensively for building purposes, 

 not only in this district, but also in other parts of the State. The quarries at 

 Batavia are worked in the side of the river bluffs, and the consequent necessity 

 of removing the superincumbent masses of Drift and surface soil is a hindrance 

 to their extension, causing a great increase in the labor and the expense of 

 working them. 



The other exposures of the Niagara group, and the limestones of the Trenton 

 and Cincinnati groups, occurring in various parts of this district, also afford a 

 supply of material suitable for foundations, rough walls, etc., and are also used 

 to some extent for general building purposes. The rock, however, is generally 

 too thinly and irregularly bedded to afford a superior quality of building stone, 

 Large portions of this district, however, are entirely destitute of a local supply 

 of building stone, and in some parts this material, whenever it is required, must 

 be transported a distance of from ten to eighteen miles. 



