ILLINOIS STATE GEOLOGICAL SURVEY. 



MONOGRAPH No. 1. PLATE XXXVI. 



6 



15 



18 



25 



3O 



35 



10 



16 



17 





19 



20 21 



22 



26 



27 



28 



29 



31 



32 



33 



34 



36 37 



38 



M 



39 



45 



46 



48 



44 



> 



fl 



49 



5O 



51 



52 



11 



13 12 



23 



24 



40 



41 42 



43 



i 



53 



