Surface Geologic Map of Ohio
Covering most of Ohio's bedrock is glacial sediment laid down in the last million years. The pale yellow belt along the east side was never glaciated, but glacial outwash features are marked on it. The most recent, Wisconsinan glaciation, which ended 14,000 years ago (14 ka), laid down the wide striped belt of green features. The earlier Illinoian glaciation (300-130 ka) left the narrow tan belt, and still earlier glaciations left a small area depicted in brown. The blue area in the north shows where Lake Erie once extended beyond its current shores.
Glaciated regions tend to have abundant resources of sand and gravel.
See a larger, 1100x1425 pixel version (775 KB), which also includes an explanation of each colored unit.
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