The Pennington 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 ...

named for

Pennington Gap, Virginia Pennington Gap is the most populous town in Lee County, Virginia, United States. The population was 1,781 at the 2010 census. The Lee Regional Medical Center was in Pennington Gap until it closed in October 2013, and the United States Penitentia ...

.Butts, Charles.
Geology and Oil Possibilities of the Northern Part of Overton County, Tenn., and of Adjoining Parts of Clay, Pickett and Fentress Counties
', pp. 25-26 (Williams Printing 1919). It can be found in outcrops along Pine Mountain and Cumberland Mountain in

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 ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...

, and

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to ...

, where it is the uppermost

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 ...

-age formation. The name has also been applied to similar Mississippian strata in the Cumberland Escarpment of eastern Kentucky, though the rocks in that area were later renamed to the Paragon Formation.Ettensohn, Frank et al.
"Slade and Paragon Formations — New Stratigraphic Nomenclature for Mississippian Rocks Along the Cumberland Escarpment in Kentucky"
''U.S. Geological Survey Bulletin 1605-B'', p. 4 (1984). According to general usage among geologists, the Pennington Formation corresponds to

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

s, and thin limestone beds located above the highest massive limestone bed of the Newman Formation. Paleosols have also been preserved in a Pennington outcrop at

Pound Gap The Pound Gap of Pine Mountain is on the Virginia/Kentucky border between Jenkins, Kentucky and Pound, Virginia. It served as a passage for early settlers to cross into Kentucky from Virginia. Today, U.S. Route 23 passes through the gap. History ...

, recording a series of fluctuations in climate between dry and wet conditions. The Pennington Formation has been inferred to represent a coastal environment transitioning between a Mississippian marine basin and Pennsylvanian coal swamps. Some parts of the Pennington Formation preserve

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, including

conodont Conodonts ( Greek ''kōnos'', " cone", + ''odont'', " tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, w ...

s which are useful for biostratigraphic dating. Conodont dating indicates that the Pennington Formation formed near the end of the Mississippian subperiod of the Carboniferous period. The Pennington Formation is considered equivalent to the Hinton, Princeton, and Bluestone formations of the

Mauch Chunk Group The Mauch Chunk Group is a geologic group in West Virginia. It preserves fossils dating back to the Carboniferous period. See also * List of fossiliferous stratigraphic units in West Virginia This article contains a list of fossil-bearing s ...

, which is exposed further north in

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...

References

Bibliography

* Carboniferous geology of Virginia Carboniferous southern paleotropical deposits {{Virginia-geologic-formation-stub