| Geology of the County | ||
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In Monroe County, water is obtained from consolidated sedimentary rocks of Ordovician, Silurian, Devonian, and Mississippian ages, and from unconsolidated sediments of Quaternary age. Geologists call the oldest rocks found at the surface in Monroe County the Liepers Limestone. This formation was deposited in warm seas 450 million years ago, during the Ordovician Period. Above the Ordovician rocks are the Silurian rocks. Above the Silurian rocks is the Devonian Chattanooga shale, 400 million years old, which was formed when the deep sea floor became covered with an organic black muck. The muck is now hard black shale (an oil shale) and is one of the most distinctive of all geologic formations in Kentucky. The Mississippian sandstones and siltstones are the result of a great influx of mud, silts, and sands brought in by rivers and streams from uplands many miles away and deposited as a great delta. The Mississippian limestones found in Monroe County were deposited 350 million years ago in the bottom of a warm, shallow sea. Over the last million years unconsolidated Quaternary sediments have been deposited along the larger streams and rivers. Geologic Formations in the County Limestones Fractured shales Interbedded limestones and shales For more information, see the definitions of geologic terms and rock descriptions, a geologic map of Monroe County, a summary of the geology of Kentucky, and a discussion of fossils and prehistoric life in Kentucky. Previous--Next--Back to "Groundwater Resources in Kentucky"
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