page_title: Geology of Illinois
hierarchical_section_title: Geology of Illinois
caption_attribution_description: English: Portion of global paleogeographic reconstruction of the Earth in the middle Devonian period 385 million years ago, showing Eastern North America with key features labeled
context_page_description: The strata of the bedrock geology of Illinois are dominated by Pennsylvanian age rocks which occur within the Illinois Basin.
context_section_description: The strata of the bedrock geology of Illinois are dominated by Pennsylvanian age rocks which occur within the Illinois Basin.
caption: Paleogeographic reconstruction showing the Illinois Basin area during the Middle Devonian period.[1]
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