Geology of the County

In Fayette County, water is obtained from consolidated sedimentary rocks of Ordovician age and from unconsolidated sediments of Quaternary age. The oldest rocks exposed on the surface in Fayette County are from the High Bridge Group, and were deposited in shallow seas 490 million years ago during the Ordovician Period. In the Late Ordovician the seas became relatively shallow, as indicated by the amounts of mud (shale) in the sediments. When the waters were clear and warm, a profusion of animal life developed, particularly brachiopods and bryozoa. Over the last million years, unconsolidated Quaternary sediments have been deposited along the larger streams and rivers.

Geologic Formations in the County
Upper part of Lexington Limestone (Ol) (Strodes Creek, Millersburg, Tanglewood Limestone, Devils Hollow, Stamping Grounds, Sulfur Well, Brannon Members)
Lower part of Lexington Limestone (Ol) (Grier, Logana, Curdsville Members)
High Bridge Group (Tyrone Limestone, Oregon Formation, Camp Nelson Limestone) (Ohb)

Knox Group (Okx)

Interbedded clay shales, siltstones, and sandstones
Garrard Siltstone (Okc)

Interbedded limestones and shales
Clays Ferry Formation (Okc)

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

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