The Cumnock Formation is a

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

-age

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 ...

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia a ...

. It is found in the of the

Sanford sub-basin Sanford may refer to: People * Sanford (given name), including a list of people with the name * Sanford (surname), including a list of people with the name Places United States * Sanford, Alabama, a town in Covington County * Sanford, Colorad ...

of the

Deep River Basin Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary), ...

, the southernmost of the large

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Creta ...

basins forming the

Newark Supergroup The Newark Supergroup, also known as the Newark Group, is an assemblage of Upper Triassic and Lower Jurassic sedimentary rocks which outcrop intermittently along the United States East Coast. They were deposited in a series of Triassic basins ...

. It is the middle unit of the

Chatham Group The Chatham Group is a Triassic-age geologic group in the eastern United States. It is one of the most fossiliferous sections of the Newark Supergroup, preserving much of the Late Triassic up until the Triassic-Jurassic mass extinction. The grou ...

, overlying the

Pekin Formation The Pekin Formation is a Late Triassic (Carnian) geological formation in North Carolina. The Pekin Formation is specific to the Sanford Sub-Basin of the Deep River Basin of North Carolina, although it may be equivalent to the Stockton Formation of ...

and underlying the

Sanford Formation The Sanford Formation is a Late Triassic (Norian)-age geologic formation in North Carolina. It is mainly found in the Sanford sub-basin of the Deep River Basin, the southernmost of the large Mesozoic basins forming the Newark Supergroup. It is th ...

. Both of these encompassing formations are primarily red

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 ...

. The Cumnock Formation, on the other hand, represents a sequence of darker

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

(lake) or

paludal Paludal is derived from the Latin word ''palus'' ("marsh"). *Paludal, in geology, refers to sediments that accumulated in a marsh environment. *Paludal, in ecology Ecology () is the study of the relationships between living organisms, inclu ...

(swampy/marshy) sediments deposited in a tropical climate. These primarily include

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 ...

s and

coal Coal is a combustible black or brownish-black sedimentary rock, formed as stratum, rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen ...

, with some thin layers of coarser sediment such as

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

and sandstone. The formation preserves some fossils, including a diverse assemblage of microvertebrates (tiny fragments of

vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

fossils) from a quarry near

Moncure, NC Moncure, founded in 1881, is a small rural unincorporated community in southeastern Chatham County, North Carolina, United States. Moncure and the neighboring community of Haywood form the Moncure census-designated place (CDP), which had a popul ...

Palynology Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and ''-logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposits ...

and general geological characteristics suggest that the Cumnock Formation is equivalent in age to the

Cow Branch Formation The Cow Branch Formation is a Late Triassic (Carnian to Norian, or Tuvalian in the regional stratigraphy) geologic formation in the eastern United States.Dan River The Dan River flows in the U.S. states of North Carolina and Virginia. It rises in Patrick County, Virginia, and crosses the state border into Stokes County, North Carolina. It then flows into Rockingham County. From there it flows back into ...

/ Danville basin on the

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 ...

-North Carolina border. It has also been compared to the

Stockton Stockton may refer to: Places Australia * Stockton, New South Wales * Stockton, Queensland, a locality in the Cassowary Coast Region New Zealand *Stockton, New Zealand United Kingdom *Stockton, Cheshire *Stockton, Norfolk *Stockton, Chirbu ...

and Lockatong formations of the

Newark Basin The Newark Basin is a sediment-filled rift basin located mainly in northern New Jersey but also stretching into south-eastern Pennsylvania and southern New York. It is part of the system of Eastern North America Rift Basins. Geology Approximat ...

in the northeastern United States. Some authors even reduce the Cumnock Formation to a member of the Lockatong Formation, in a broad interpretation of the latter. The Cumnock Formation is probably early

Norian The Norian is a division of the Triassic Period. It has the rank of an age ( geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic ...

in age based on comparisons to similar strata in the eastern United States, as well as early sections of the

Chinle Formation The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In ...

further west.

References

* Triassic geology of North Carolina {{Triassic-stub

See also

References