The Columbus Limestone is a mapped bedrock unit consisting primarily of

fossil 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 ...

iferous

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 ...

, and it occurs in Ohio, Pennsylvania, and Virginia in the United States, and in Ontario, Canada.

Description

Depositional environment

The

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will b ...

was most likely shallow marine.

Stratigraphy

The Columbus conformably overlies the Lucas Dolomite in northeastern Ohio, and unconformably overlies other dolomite elsewhere. It

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

underlies the Ohio Shale in northwestern Ohio and the Delaware Limestone in eastern Ohio. Its members include: Bellepoint, Marblehead, Tioga Ash Bed, Venice, Delhi, Klondike, and East Liberty.

Notable Exposures

*The type section is located in

Columbus, Ohio Columbus () is the state capital and the most populous city in the U.S. state of Ohio. With a 2020 census population of 905,748, it is the 14th-most populous city in the U.S., the second-most populous city in the Midwest, after Chicago, an ...

. *The

glacial grooves Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them w ...

on Kelleys Island are cut into the Columbus Limestone. It is also

quarried A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their environ ...

there. *An exposure in Ontario is located at

Ingersoll, Ontario Ingersoll is a town in Oxford County on the Thames River in southwestern Ontario, Canada. The nearest cities are Woodstock to the east and London to the west. Ingersoll is situated north of and along Highway 401. Oxford County Road 119 (formerl ...

Fossils

The Columbus Limestone contains

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, ...

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...

ns,

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

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 ...

s, stromatoporoids and

echinoderms An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the ...

(including

crinoid Crinoids are marine animals that make up the Class (biology), class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or coma ...

s). Due to their mid-continent depositional environment, the fossils are almost free of

deformation Deformation can refer to: * Deformation (engineering), changes in an object's shape or form due to the application of a force or forces. ** Deformation (physics), such changes considered and analyzed as displacements of continuum bodies. * Defo ...

caused by tectonic activity common in the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. The ...

. Tabulate corals include ''

Syringopora ''Syringopora'' is an extinct genus of phaceloid tabulate coral. It has been found in rocks ranging in age from the Ordovician to the Permian, although it was most widespread during the Silurian, Devonian The Devonian ( ) is a geologic peri ...

tabulata'', ''

Favosites ''Favosites'' is an extinct genus of tabulate coral characterized by polygonal closely packed corallites (giving it the common name "honeycomb coral"). The walls between corallites are pierced by pores known as mural pores which allowed transfer ...

hemispherica minuta'', ''Emmonsia polymorpha'', ''Thamnoptychia alternans'', ''Pleurodictyum sp.'', and ''

Coenites ''Coenites'' is an extinct genus of prehistoric corals in the family Coenitidae. ''C dublinensis'' occurs in the Columbus Limestone, a mapped bedrock unit consisting primarily of fossiliferous limestone, and it occurs in Ohio, Pennsylvania, and V ...

dublinensis''.

Rugose Rugose means "wrinkled". It may refer to: * Rugosa, an extinct order of coral, whose rugose shape earned it the name * Rugose, adjectival form of rugae Species with "rugose" in their names * ''Idiosoma nigrum'', more commonly, a black rugose trap ...

corals include ''Prismatophyllum rugosum'', ''Hexagonaria anna'', ''Eridophyllum seriale'', ''Synaptophyllum simcoense'', ''Amplexus yandelli'', ''Zaphrenthis perovalis'', ''Heterophrentis nitida'', ''Cystiphylloides americanum'', ''Odontophyllum convergens'', ''Siphonophrentis gigantea''. Brachiopods include ''Spirifer macrothyris'' and ''Brevispirifer gregarius'' (see

Spiriferida Spiriferida is an order of extinct articulate brachiopod fossils which are known for their long hinge-line, which is often the widest part of the shell. In some genera (e.g. '' Mucrospirifer'') it is greatly elongated, giving them a wing-like ap ...

). The gastropod (snail) ''Laevidentalhum martinei'' is present, as well as the crinoid ''Nucleocrinus verneulli''. Fish fossils have been found in the East Liberty Member ("East Liberty bone bed").

Goniatites ''Goniatites'' is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. '' Hibernicoceras'' and '' Hypergoniatites'' are among related genera. Species Description The shell is general ...

have been found in the Columbus, including ''Werneroceras staufferi'' and ''Tornoceras eberlei''. Another cephalopod species is ''Goldringia cyclops''.

Age

Relative age dating of the Columbus Limestone places it in the Early to Middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

period.

Economic Uses

The Columbus has been mined for

aggregate Aggregate or aggregates may refer to: Computing and mathematics * collection of objects that are bound together by a root entity, otherwise known as an aggregate root. The aggregate root guarantees the consistency of changes being made within the ...

. Its Calcium carbonate content is 90% or higher.GeoFacts No. 25, Ohio Department of Natural Resources, Division of Geological Survey