ILLINOIS STATE GEOLOGICAL SURVEY. MONOGRAPH No. 1. PLATE XXIII. 



11 



9 



10 



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18 



15 



12 



13 



14 



16 



28 29 



I 



20 21 22 



23 



24 25 26 27 



> 



3O 31 32 



33 



34 35 



* 



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42 43 44 45 



41 



38 39 4O 



46 47 48 49 5O 51 52 53 



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60 59 



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54 



