The Bowen Formation is an

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...

-age

geological 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 expo ...

in the

Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, ...

n region of the eastern United States. It occupies a thin stratigraphic range between the Wardell and

Witten Witten () is a city with almost 100,000 inhabitants in the Ennepe-Ruhr-Kreis (district) in North Rhine-Westphalia, Germany. Geography Witten is situated in the Ruhr valley, in the southern Ruhr area. Bordering municipalities * Bochum * Dort ...

formations in some areas of southwest

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 northeast

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 ...

. It is particularly well-exposed in

Tazewell County, Virginia Tazewell County () is a county located in the southwestern portion of the U.S. state of Virginia. As of the 2020 census, the population was 40,429. Its county seat is Tazewell. Tazewell County is part of the Bluefield, WV-VA Micropolitan ...

. Unlike its encompassing strata, the Bowen Formation is mostly

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an a ...

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 ...

and

mudrock Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sma ...

rather than

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 ...

. The thicker upper part of the formation is composed of layered red mudrock which is replete with

mudcrack Mudcracks (also known as mud cracks, desiccation cracks or cracked mud) are sedimentary structures formed as muddy sediment dries and contracts.Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA, ...

s. The thinner lower part, which is not always preserved, is a coarser unit of dark grey stratified sandstone which weathers to a rusty-brown color. Fossils are rare, restricted to

stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations ( microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). ...

s and ''Tetradium fibratum'' (a

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secre ...

-like colonial organism). The Bowen Formation was probably formed by a small lobe of a

delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D (NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also r ...

flowing northeast onto the

carbonate platform A carbonate platform is a sedimentary body which possesses topographic relief, and is composed of autochthonic calcareous deposits. Platform growth is mediated by sessile organisms whose skeletons build up the reef or by organisms (usually mic ...

s of the area. Mudcracks indicate that the sediments were partially exposed to the air. Shortly after deposition of the Witten Formation, similar conditions would return in force with the thick coastal

red beds Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain th ...

of the

Moccasin Formation The Moccasin Formation is a geologic formation in Virginia and Tennessee. It preserves fossils dating back to the Ordovician period. See also * List of fossiliferous stratigraphic units in Virginia * Paleontology in Virginia Paleontology in V ...

References

* Ordovician geology of Virginia Ordovician southern paleotemperate deposits {{Virginia-geologic-formation-stub