by S. W. Parr .

University of Illinois 1914-1915 Bulletin / State of Illinois. State Geological Survey No. 29, 31

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by Raymond S. Blatchley

University of Illinois 1913 Bulletin / State of Illinois. State Geological Survey no. 22

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by E.W. Shaw and T.E. Savage ; surveyed in cooperation with the Geological Survey of Illinois

U.S. Geological Survey 1912 Geologic atlas of the United States no. 185

Cartographic Material (Map)

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by Edward Bartow ... [et al.]

University of Illinois 1909 Bulletin / State of Illinois. State Geological Survey no. 10

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by James Walter Goldthwait

University of Illinois 1909 Bulletin / State of Illinois. State Geological Survey no. 11

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Illinois State Geological Survey

Illinois State Geological Survey

by J Harlen Bretz

State Geological Survey 1923

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