Geology of the County

In Metcalfe County, water is obtained from consolidated sedimentary rocks of Ordovician, Devonian, and Mississippian age, and from unconsolidated sediments of Quaternary age. Geologists call the oldest rocks found at the surface in Metcalfe County the Leipers Limestone. This formation is from the Ordovician, and was deposited in warm seas 450 million years ago. Above the Ordovician rocks is the Devonian black 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 Metcalfe 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
Unconsolidated deposits
Alluvium (Qa)

Steve Genevieve Limestone Member of Monteagle Limestone (Mgl)
St. Louis Limestone (Mgl)
Salem and Warsaw Formations (Msh)
Fort Payne Formation (Mbf), limestone bodies within Fort Payne (ls)

Fractured shales
Chattanooga Shale (MDnb)

Interbedded limestones and shales
Cumberland Formation, Leipers Limestone, Catheys Formation (Ocl)

Interbedded limestones, sandstones, and shales
Girkin Formation (Reelsville Limestone, Sample Sandstone, Beaver Bend and Paoli Limestone) (Mcl)

For more information, see the definitions of geologic terms and rock descriptions, a geologic map of Metcalfe County, a summary of the geology of Kentucky, and a discussion of fossils and prehistoric life in Kentucky.

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