ILLINOIS STATE GEOLOGICAL SURVEY. 



MONOGRAPH No. 1. PLATE XXXV. 



J 



9 



11 



12 



13 14 



'6 



21 



16 



22 



23 24 25 26 



32 



27 



28 29 30 



31 34 



10 



15 



17 18 iQ 20 



33 



' 



"IS 



35 



62 63 



68 



