The Chepultepec Formation, is an

Early 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 exp ...

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, Ca ...

n regions of Eastern North America. Also known as the Chepultepec Dolomite, it is a unit of the Upper Knox Group, overlying the

Copper Ridge Dolomite The Copper Ridge Dolomite is a geologic formation in Alabama. It preserves fossils dating back to the Cambrian Period. See also * List of fossiliferous stratigraphic units in Alabama This article contains a list of fossil-bearing stratigraph ...

and underlying the Longview- Kingsport-

Mascot A mascot is any human, animal, or object thought to bring luck, or anything used to represent a group with a common public identity, such as a school, professional sports team, society, military unit, or brand name. Mascots are also used as fi ...

sequence. The Chepultepec Formation is a primarily

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 whe ...

and

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

formation, the earliest formation of the

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

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

in its area. Further north, it is equivalent to the Stonehenge Formation of the

Beekmantown Group The Beekmantown Group is a late Cambrian to lower–middle Ordovician Group (geology), geologic group that occurs in the eastern Canada (Québec) and northeastern United States, datable from its conodont fauna. It contains Dolomite (mineral), do ...

. The formation was first described from

Allgood, Alabama Allgood, formerly known as Chepultepec, is a town in Blount County, Alabama, United States. At the 2020 census, the population was 548. History One source said the town's name comes from a family of homesteaders from South Carolina who settled i ...

, and has also been found in

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 th ...

and

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

. Allgood was originally named "Chepultepec", providing its name to the formation as well. In Virginia, the Chepultepec Formation has a habit of forming large natural

arch An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it. Arches may be synonymous with vaul ...

es, including Natural Tunnel in Scott County and

Natural Bridge A natural arch, natural bridge, or (less commonly) rock arch is a natural landform where an arch has formed with an opening underneath. Natural arches commonly form where inland cliffs, coastal cliffs, fins or stacks are subject to erosion fr ...

Rockbridge County Rockbridge County is a county in the Shenandoah Valley on the western edge of the Commonwealth of Virginia. As of the 2020 census, the population was 22,650. Its county seat is the city of Lexington. Rockbridge County completely surrounds the ...

References

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