Geology of the County

In Bath County, water is obtained from consolidated sedimentary rocks of Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian age, and from unconsolidated sediments of Quaternary age. The oldest rocks found on the surface in Bath County are from the Ordovician Period, and were deposited in shallow seas 490 million years ago. The Devonian New Albany Shale, 400 million years old, was formed when the deep sea floor became covered with an organic black muck. The muck is now hard black shale (an oil shale), which 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 to the northeast and deposited as a great delta. The Mississippian limestone found in Bath County was deposited 350 million years ago in the bottom of a warm, shallow sea. At the end of the Mississippian Period, 320 million years ago, the seas receded and sediments of the Pennsylvanian Period were deposited. The warm climate of the Pennsylvanian allowed extensive forests and great coastal swamps to grow at the edges of water bodies. Marine waters advanced and receded many times, which produced many layers of sandstone, shale, and coal. Vegetation of all sorts fell into the water and was buried under blankets of sediment, which over long geologic time was compressed into coal. The nonvegetative sediments such as sand, clay, and silt were compressed into sandnstone and shale. 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)

Slade Formation (Mn)

Grundy Formation (contains Lee-type sandstone of the former Lee Formation) (Plc)

Interbedded clay shales and sandstones
Borden Formation (MDbb)

Fractured shales
New Albany Shale (MDnb)
Boyle Dolomite (MDnb)

Interbedded limestones and shales
Drakes Formation (Odb)/Bull Fork Formation (Ob)
Grant Lake Limestone/Fairview Formation/Calloway Creek Limestone (Oaf)
Garrard Siltstone (Okc)
Clays Ferry Formation (Okc)

Clay shales
Crab Orchard Formation and Brassfield Dolomite (Scb)

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

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