Quaternary Geologic Map of the Chicago 4° x 6° Quadrangle, United States

The Quaternary Geologic Map of the Chicago 4° x 6° Quadrangle
was mapped as part of the Quaternary Geologic Atlas of the United States.
The atlas was begun as an effort to depict the areal distribution of
surficial geologic deposits and other materials that accumulated or
formed during the past 2+ million years, the period that includes all
activities of the human species. These materials are at the surface of
the earth. They make up the "ground" on which we walk, the "dirt" in
which we dig foundations, and the "soil" in which we grow crops. Most
of our human activity is related in one way or another to these surface
materials that are referred to collectively by many geologists as
regolith, the mantle of fragmental and generally unconsolidated material
that overlies the bedrock foundation of the continent. The maps were
compiled at 1:1,000,000 scale.