48 GEOLOGY OF ILLINOIS. 



The shale over the coal was filled with fossil shells, corals, etc. The 

 limestone over this coal was also seen three miles north-west of Law's 

 place, where it was formerly quarried and burned for lime. 



A quarter of a mile below the Big Creek bridge, south of Olney, 

 found the following section : 



Ft. 



Soil and drift 15 



Coarse irregularly bedded sandstone 15 



Black marly shale ; 13 



The lower part of the black shale was slaty and contained numerous 

 fossils, Pleurotomaria tabulate,, P. Grayvillensis, Belter ophon per car inatus, 

 B. Mont/or tianus, B. carbonarius, Athyris suMilita, Productus longispinus, 

 Nucula ventricosa, Orthoceras Bushensis; and Lophophyllum proliferum. 

 At James C. Stewart's place, four and a half miles south-west of 

 Olney, a black shale outcrops in the banks of Sugar creek about five 

 feet thick, underlaid by a thiu coal. A quarter of a mile below at the 

 bridge saw the same conglomerate sandstone that occurs on Big creek, 

 underlaid by the same black shale, which was sometimes marly and 

 contained the fossils mentioned above. It also contains large nodules 

 of impure limestone." 



This bituminous shale and thin coal probably represents coal No. 13 

 of the general section, and this same group of fossils occurs in connec- 

 tion with this coal on the East fork of Shoal creek in Montgomery 

 county. 



E conomical Geology. 



Building Stone. — Sandstone of a fair quality for ordinary use is quite 

 abundant, and there is probably not a township in the county where 

 good quarries could not be opened at a moderate expense. Many of 

 these localities have been mentioned in the preceding pages, and but 

 little needs to be said farther in regard to them. The quarries south of 

 Clermont, belonging to the O. and M. railroad, afford a very hard and 

 durable rock, and although the bed is only about sis feet in average 

 thickness, it is, fortunately, so situated as to require no great expendi- 

 ture in stripping, and the rock has already been removed over a surface 

 of several acres iu extent. The rock is a very hard, gray, micaceous 

 sandstone and seems to be but little affected by long exposure, and hence 

 affords a desirable material for culverts, bridge abutments, etc. The 

 sandstones in the northern and western portions of the county are for 

 the most part rather soft, but locally they afford some very good build- 

 ing stone, as at Mr. Heap's quarry northeast of Olney, and at DarliDg's 

 quarry two miles west of that town. The stratum of hard, silicious 

 limestone outcropping on Big creek two miles and a half south of Olney 

 is a durable stone, but is not to be obtained in sufficient quantity to be 

 of much importance as a building stone. 



