246 GENEBAL GEOLOGY. 



the whole formation in our State, particularly as the litholog- 

 logical characters here described, are the prevailing ones 

 throughout its whole extent. 



DESCRIPTION OF THE SECTION AT WINTEESET. 



16. Thin bedded, yellowish-gray limestone 1 foot. 



15. Fossiliferous, marly clay 4 feet. 



14. Massive, light gray limestone 6 feet. 



13. Compact, regularly bedded limestone with marly partings. . . 12 feet. 



12. Black, fissile, carbonaceous shale 2 feet. 



11. Compact, regularly bedded limestone, with marly partings. . . 34 feet. 



10. Black, fissile, carbonaceous shale 2^ feet. 



9. Grayish limestones, often silicious and impure 15 feet. 



8. Compact, heavy bedded limestone 2 feet. 



7. Grayish limestones, often cherty, and sometimes finely arena- 

 ceous 163^ feet. 



6. Impure coal 3^ foot. 



5. Light bluish, marly clay 2 feet. 



4. Light bluish, concretionary and fragmentary limestone 5 feet. 



3. Bluish and reddish clays , 6 feet. 



2. Fine grained shaly sandstone and sandy shales 71 feet. 



1. Bluish, shaly, impure limestone X% feet. 



Total 181 feet. 



No. 1, of this section, belongs to the Middle coal-measures ; all the remainder, 

 to the Upper coat-measures. The locality thus receives additional interest by 

 exhibiting the junction between the two formations. Deducting No. 1, we have 

 remaining nearly one hundred and eighty feet in vertical thickness of Upper 

 coal-measure strata, and yet this locality, as before remarked, is only ten miles 

 distant from the thinned-out edge of the formation. 



Other sections, illustraing exposures of strata of this forma- 

 tion, will be found among the descriptions of the geology of 

 various regions and counties in Paet III; the Winterset 

 section being selected for insertion here as typical of the 

 general characters of the formation. 



As shown in the preceding section, there are throughout the 

 whole formation occasional layers of decidedly carbonaceous 

 material, which, although very much too impure for fuel, is 

 nevertheless to a certain extent combustible. One of these 

 carbonaceous horizons, and only one, so far as known, 



