The Girkin Formation is a
geologic formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
located in the
Chester Escarpment of central
Kentucky
Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virgini ...
, USA. It comprises a level of
Mammoth Cave
Mammoth Cave National Park is an American national park in west-central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world.
Since the 1972 unification of Mammoth Cave with the even-longer system under F ...
and lies above the
Ste. Genevieve Limestone and
St. Louis Limestone
The St. Louis Limestone is a large geologic formation covering a wide area of the midwest of the United States. It is named after an exposure at St. Louis, Missouri. It consists of sedimentary limestone with scattered chert beds, including th ...
and below the
Big Clifty Sandstone in that area. The Girkin is a
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...
Mississippian
Mississippian may refer to:
* Mississippian (geology), a subperiod of the Carboniferous period in the geologic timescale, roughly 360 to 325 million years ago
*Mississippian culture, a culture of Native American mound-builders from 900 to 1500 AD ...
in age.
Members of the Girkin are as follows in descending order:
*
Beech Creek Member
*
Elwren Member
*
Reelsville Member
*
Sample Member
*
Beaver Bend Member
*
Bethel Member
*
Paoli Member
References
Geologic formations of Kentucky
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