Greenbrier Group

The Greenbrier Limestone, also known locally as the "Big Lime", is an extensive limestone unit deposited during the Middle Mississippian Epoch (345.3 ± 2.1 – 326.4 ± 1.6 Ma), part of the Carboniferous Period. This rock stratum is present below ground in much of West Virginia and neighboring Kentucky, and extends somewhat into adjacent western Maryland and southwestern Virginia. The name derives from the Greenbrier River in West Virginia.

Greenbrier Limestone
Stratigraphic range: Middle Mississippian
The Sinks of Gandy (an underground stream) is developed in the Greenbrier Limestone Formation in West Virginia.
Type	sedimentary
Sub-units	Denmar Limestone, Taggard Shale, Pickaway Limestone, Union Limestone, Greenville Shale, and Alderson Limestone.
Underlies	Bluefield Formation
Overlies	Maccrady Formation and Price Formation
Thickness	120 m
Lithology
Primary	Limestone
Location
Region	Allegheny Mountains
Country	United States
Extent	Kentucky, Maryland, Virginia, and West Virginia
Type section
Named for	Greenbrier River

Greenbrier Limestone is in some places more than 400 feet (120 metres) thick, allowing it to trap large quantities of oil and gas. Since this carbonate rock erodes quickly in the region's wet climate, outcrops are not prominent and are often quarried.

The Greenbrier Limestone is subdivided into six stratigraphic units. In ascending order, they are Denmar Limestone, Taggard Shale, Pickaway Limestone, Union Limestone, Greenville Shale, and Alderson Limestone. The limestones in this interval are predominantly skeletal grainstones or packstones. The Pickaway and especially the Union contain oolitic grainstones.

Numerous solution caves are developed within the Greenbrier Formation.