Guide to the Geologic Map of Illinois

Before the cornfields and cities, before the rivers carved their paths, immense glaciers sculpted Illinois into the landscape we know today. This official guide to the state's geologic map reveals that history frozen in stone - layer upon layer of ancient seas, glacial deposits, and bedrock formations that tell a story spanning hundreds of millions of years. Produced by the Illinois State Geological Survey, it explains how to read the map's colors and symbols as a language of deep time, showing where limestone bedrock lies beneath the surface, where glacial till blankets the northern counties, and where ancient river valleys now hide beneath modern topography. Whether you're a geology student, an educator, or someone who wants to understand the ancient forces that shaped the ground beneath your feet, this guide transforms a map into a time machine.