-33- 



Purington Shale member 



Oak Grove 



Limestone 



Member 



Mecca Quarry 

 Shale Member 



Francis Creek 



Shale 



M ember 



Colchester 

 (No.2) Coal Member 



III.) 



13 



14 



Scale 



1. Shale - medium gray; contains flat 

 ferruginous concretions; slightly 

 fossiliferous . 



2. "Cast band limestone" - tan; contains 

 casts of pelecypods and gastropods. 



3. Shale - dark gray, well-bedded. 



4. "Linoproductus limestone" - blue 

 gray to rusty brown; contains 

 abundant brachiopods, brachiopod 

 spines, gastropods, and crinoidal 

 debris. 



5. Shale - dark gray, slightly fos- 

 siliferous . 



6. Limestone - dark brownish gray, 

 limonitic, lenticular; contains 

 impressions of pelecypods. 



7. " Dunbarella shale" - dark gray, 

 well-bedded; contains Dunbarella , 

 Aviculopecten , and Lingula . 



8. "Pelecypod limestone" - dark brownish 

 gray, argillaceous; contains os_tra- 

 cods , Lingula , and Orbiculoidea . 



9. " Mesolobus shale" - dark gray, cal- 

 cific, slightly fossiliferous; con- 

 tains Mesolobus at base. 



10. "Gray septarian limestone" - medium 

 blue gray; nodular but forms nearly 

 continuous bed; contains a thin 

 shale parting; upper part contains 

 Marginifera , Cornuspira , and Ammo- 

 discus . 



11. Shale - dark gray, becomes lighter 

 in color upward, calcitic, thin- 

 bedded; the base contains pelecypod 

 fragments , Ammodiscus , and some 

 crinoidal debris . 



12. "Crinoidal limestone" - medium gray, 

 medium-grained, impure. 



13. Shale - black, "slaty," hard; middle 

 portion contains small phosphatic 

 nodules giving pimple structure. 



14. Shale - medium dark gray, soft, poorly 

 laminated, burrowed, fossiliferous. 



15. Shale - light gray, soft, fairly well 

 laminated, slightly fossiliferous. 



16. Coal - exposed at river level during 

 low water. 



Fig. 15 - WOLF COVERED BRIDGE, cutbank on Spoon River at Wolf Covered Bridge, 

 Wdh NE% Sec. 13, T. 10 N., R. 3 E., Knox County, Maquon Quadrangle, 

 Conodont assemblages may be collected from the Mecca Quarry Shale 

 Member of the Carbondale Formation. The macro-fauna alone merits 

 a visit. The locality is a few miles east of Knoxville. Follow 

 signs from U.S. Route 150 or Illinois Route 97. (Section taken 

 from Smith et al., 1970.) 



