Geology of the County
 

In Green County, water is obtained from consolidated sedimentary rocks of Mississippian age and from unconsolidated sediments of Quaternary age. Geologists call the oldest rocks found at the surface in Green County the Borden Formation. 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 most common rock types in Green County are Mississippian limestones, which 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)

Limestones
Ste. Genevieve Limestone (Mgl)
St. Louis Limestone (Mgl)
Salem, Warsaw, Harrodsburg Formations (Msh)
Fort Payne Formation (Mbf) (ls)
Borden Formation (Muldraugh (Mbf)

Interbedded limestones, sandstones, and shales
Glen Dean Limestone, Hardinsburg Sandstone (Mcl)
Golconda Formation (Haney Limestone, Big Clifty Sandstone, Beech Creek Limestone Members) (Mcl)
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 Green County, a summary of the geology of Kentucky, and a discussion of fossils and prehistoric life in Kentucky.

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