The southeast Missouri and Illinois-Kentucky districts are two of the most important mineral districts in the country in terms of variety of minerals produced, mineral output, and mineral potential. Both districts lie on faulted structural uplifts within the covered shield area of the Central States. Complex fault lineaments intersect in each district and are major structural controls. Two fault zones, the Ste. Genevieve and Cottage Grove, form connecting links between districts. The iron deposits of southeast Missouri are in rocks of Precambrian age; but the lead, zinc, barite, copper, cobalt, and pyrite deposits of southeast Missouri, and the fluorite, zinc, barite, lead deposits of Illinois-Kentucky, are all in the domed and faulted thin cover of Paleozoic rocks.

Geology of Illinois has been compiled from more than a century of earth science investigations in Illinois. For the first time, this information has been summarized and made accessible in one volume to help both geologists and non-geologists better understand how the state's mostly unseen geology affects, and is affected by, life on the surface. More than 200 color photographs, maps, and drawings illustrate the text. Topics include : the history of geological investigations in Illinois; the impact of the state's tectonic and structural history; the properties and classification of its rocks and sediments; the rich heritage of its land, water, and mineral resources; the threats from its geological hazards; and the application of geological information to societal issues.