48 ECONOMICAL GEOLOGY. 



on Sugar Creek, in Sangamon county, used in the construction of 

 the Old State House at Springfield. 



The most characteristic fossils of this limestone are Productus 

 Nebrascensis, P. Prattcnianus, P. punctatus, Spirifer cameratus, Athyris 

 siibtilita, Pinna per-acuta, crinoidal joints, and, rarely, the body of a 

 Eiipachycrinus or Poteriocrinus. A few fish teeth and spines have 

 also been obtained from this limestone. 



The lower division of the limestone No. 3 of the foregoing section, 

 which may be regarded as a distinct bed, is quite argillaceous and 

 of but little value as a building stone. It is unevenly bedded, and 

 the layers are separated by shaly partings, that are, at some points, 

 completely filled with fossil shells. The fossils of this limestone are 

 Athyris siibtilita, Terebratula bovidens, Spirifer cameratus, S. liiieatus, 

 Productus longispinus, Spiriferina Kentuckensis, Platyostoma Peoriense, 

 numerous corals not yet determined, and casts of Pleurotomaria, 

 Bellerophon and Nautilus of several species. 



I have been inclined to regard this limestone as the equivalent of 

 that at Carlinville, which it resembles, both in its lithological char- 

 acters and in the specific character of its embedded fossils. If so, 

 it represents the horizon of No. 9 coal, and is the dividing line be- 

 tween the upper and lower Coal Measures. It is rather more argil- 

 laceous here than in Macoupin county, but otherwise it bears a close 

 resemblance to that rock, and its position is about where that lime- 

 stone, if present here, should be found. 



On the south side of the Illinois river there are two or three coal 

 shafts in operation, only one of which had any record of the beds 

 passed through. The Oglesby shaft furnished me the following 

 section : 



Ft. In. 

 No, 1. Drift clay and gravel 30 



No. 2. Limestone, in two beds... 25 



No. 3, Shale 7 6 



No. 4. Goal 2 



No. 5. Shale 7 6 



No. 6. Hardredrock 4 6 



No. 7. Shale 8 7 



No. 8. Sanpstone 4 11 



No. 9. Red shale 13 11 



No. 10. Gray shale A 9 2 



No. 11. Limestone .- 3 6 



No. 12. Shale 19 6 



No. 13. Hardrock 2 6 



No. 14. Shale 39 



No. 15. Sandstone 14 6 



No. 16. Shale 50 



No. 17. Black slate 18 7 



No. 18. Coal No. 7?... 3 e 



