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ILLINOIS STATE GEOLOGICAL SURVEY
John C. Frye, Chief Urbana, IL

GLACIAL MAP OF ILLINOISH.B. WILMAN and JOHN C. FRYE

1970

Modified from maps by Leverett (1899), Ekblow (1959), Leighton and Brophy (1961), Willman et al. (1967), and others.





EXPLANATION

HOLOCENE AND WISCONSINAN
Alluvium, sand dunes, and gravel terraces

WISCONSINAN
Lake deposits

WOODFORDIAN
Moraine

Front of morainic system

Groundmoraine

ALTONIAN
Till plain

ILLINOIAN
Moraine and ridged drift

Groundmoraine

KANSAN
Till plain

DRIFTLESS



FIGURE 4. GLACIAL MAP OF ILLINOIS




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