Geology of the County

In Boyd County, water is obtained from consolidated seimentary rocks of the Breathitt Formation, which is Pennsylvanian in age, and from unconsolidated sediments of Quaternary age. The sediments of the Pennsylvanian were deposited 320 million years ago. The warm climate of this period grew extensive forests and great coastal swamps 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 sediments, which over geologic time were compressed into coal. The nonvegetative sediments such as sand, clay, and silt were compressed into sandstone and shale. Over the last million years the unconsolidated Quaternary sediments have been deposited along the larger streams and rivers.

Geologic Formations in the County

Unconsolidated deposits
Alluvium (Qa)

Coals, sandstones, and shales
Breathitt Group (Pbu, Pbm)/CONEMAUGH FORMATION (Pmc) (Princess Formation, Four Corners Formation, Hyden Formation, Pikeville Formation)

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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