Illinois. Dept. of Public Works and Buildings, Service, C. M · Springfield, Ill. : Schnepp & Barnes, printers · leaf 50
47 … Wild Cat Canyon—Starved Rock Park. 48 The Glacial Drift—Overlying much of the upland surface thereis a mantle of heterogeneous material composed, in large part, of clay,but carrying within that clay many stones and boulders. This form-ation differs from all those which have been thus far described…
