Geology of the County

In Anderson 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 Kentucky are found in Anderson County--the High Bridge Group of the Ordovician System, which were deposited in shallow seas 490 million years ago. 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, the unconsolidated Quaternary sediments have been deposited along the larger streams and rivers.

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

Knox Group (Okx)

Interbedded limestones and shales
Clays Ferry Formation and Kope Formation (Okc)
Garrard Siltstone (Okc)

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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