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Coquina () is a
sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of the shells of mollusks, trilobites, brachiopods, or other
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chorda ...
s. The term ''coquina'' comes from the Spanish word for " cockle" and "shellfish". For a sediment to be considered to be a coquina, the particles composing it should average or greater in size. Coquina can vary in hardness from poorly to moderately cemented. Incompletely consolidated and poorly cemented coquinas are considered grainstones in the Dunham classification system for carbonate sedimentary rocks. A well-cemented coquina is classified as a
biosparite Fossiliferous limestone is any type of limestone, made mostly of calcium carbonate (CaCO3) in the form of the minerals calcite or aragonite, that contains an abundance of fossils or fossil traces. The fossils in these rocks may be of macroscopic ...
(fossiliferous limestone) according to the Folk classification of sedimentary rocks. Coquinas accumulate in high-energy marine and lacustrine environments where currents and waves result in the vigorous winnowing, abrasion, fracturing, and sorting of the shells that compose them. As a result, they typically exhibit well-developed bedding or cross-bedding, close packing, and good orientation of the shell fragments. The high-energy marine or lacustrine environments associated with coquinas include beaches, shallow submarine raised banks, swift tidal channels, and barrier bars.


Composition and distribution

Coquina is composed mainly of the
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
calcite, often including some phosphate, in the form of seashells or
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 se ...
. Coquinas dating from the
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, wh ...
period through to the much more recent
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
epoch are a common find all over the world, with the depositional requirements to form a coquina being a common thing in many marine facies.


History and use


Australia

Adjacent to Shark Bay Road southeast of Denham is an approximately long stretch of coastline composed of billions of tiny shells of the Shark Bay cockle ( Fragum erugatum), averaging less than in length. The shell deposit, between thick, has compacted and cemented in some areas into solid masses of limestone that formerly was quarried and cut into blocks used in local construction. St Andrew's
Anglican Anglicanism is a Western Christian tradition that has developed from the practices, liturgy, and identity of the Church of England following the English Reformation, in the context of the Protestant Reformation in Europe. It is one of t ...
Church, the Old Pearler Restaurant, and parts of the Shark Bay Hotel in Shark Bay were built from coquina shell blocks. The church, built in 1954, has walls infilled with coquina shell blocks between a light steel frame and a shell facing, while the Old Pearler was built in 1974–1977 with buttressed coquina shell block walls.


Brazil

Recently discovered petroleum-bearing formations off the coast of northeastern Brazil hold coquina reservoirs of oil. The coquinas are generally heterogeneous in their porosity and permeability, but like other lacustrine carbonates, they are uncommonly reservoirs. Corbett et al. (2015) in their discussion of the reservoirs say the finding of the Badejo Field ( Campos Basin) in 1975 was the first hydrocarbon discovery in the coquinas of the Lagoa Feia, followed by that of the Pampo and Linguado Fields in 1978. The coquinas of the Morro do Chaves Formation were formed by non-marine bivalves and
ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...
s. The shells of the bivalves, which lived in shallow oxygenated water, were transported and deposited as washout over stream fans and beaches by storms and long-shore drift. The palynological record of coquinas of the Sergipe-Alagoas Basin has been analyzed and the sediments dated to the late Barremian age; the results suggest a marine and/or brackish environment. Daniel Thompson (2013) asserts that the coquinas of the Morro do Chaves Formation include a wide range of marine mollusca characteristic of brackish environmental conditions, suggesting periodic marine ingression during the Early Cretaceous. According to a paper by Senira Kattah published in ''The Sedimentary Record'', the discovery of the Lula Field by Petrobras and partners in 2006 opened petroleum exploration in the Barremian/ Aptian pre-salt play in the offshore Santos and Campos basins, and consequently deeper coquina reservoirs have become important targets. He says the two main reservoir targets recognized for the pre-salt within the study areas are: "late rift coquinas, lacustrine facies deposited at the Late Barremian to Early Aptian, and the younger rift/sag microbial limestones deposited during the Aptian, just before the establishment of the major evaporitic sag basin between South America and Africa." There are abundant beds of coquina in the Outer High of the Santos Basin, similar to those from the neighboring Campos. Pre-salt stratigraphy of the Santos Basin shows lacustrine sediments composed of coarse
pelecypod Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biva ...
(bivalve) coquina during the Barremian and Aptian sag phase of the continental crust subsidence.


Florida

Coquina deposits in Florida occur mostly along the eastern coast of the peninsula. This coquina is named the
Anastasia Formation The Anastasia Formation is a geologic formation deposited in Florida during the Late Pleistocene epoch. Age Period : Quaternary Epoch: Pleistocene ~2.558 to 0.012 mya, calculates to a period of Faunal stage: Blancan through early Rancholabrean ...
after Anastasia Island, where the Spanish quarried the rock to construct the Castillo de San Marcos, the fortress they built to defend
St. Augustine Augustine of Hippo ( , ; la, Aurelius Augustinus Hipponensis; 13 November 354 – 28 August 430), also known as Saint Augustine, was a theologian and philosopher of Berber origin and the bishop of Hippo Regius in Numidia, Roman North Afr ...
. The Anastasia Formation stretches from just north of St. Augustine in St. Johns County to southern Palm Beach County. The formation and associated sand form part of the Atlantic Coastal Ridge, a
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
barrier island chain that extends from Duval County to Dade County. Other coquina deposits are found in the state, but only in limited areas. The Anastasia Formation is naturally exposed in a number of places along the east coast including
Washington Oaks Gardens State Park Washington Oaks Gardens State Park is a Florida State Park located near Palm Coast, Florida, along A1A. The park is most famous for its formal gardens, but it also preserves the original habitat of a northeast Florida barrier island. Ecology Ha ...
, Gilbert's Bar House of Refuge, Hutchinson Island in Martin County and Blowing Rocks Preserve, owned by The Nature Conservancy, in Martin County. Still occasionally
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 ...
or mined, and used as a building stone in
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
for over 400 years, coquina forms the walls of the Castillo in St. Augustine. The stone made a very good material for building forts, particularly those built during the period of heavy cannon use. Because of coquina's softness, cannonballs would sink into, rather than shatter or puncture the walls. The first Saint Augustine lighthouse, built by the Spanish, was also made of coquina. Coquina was used as building stone in St. Augustine as early as 1598 for construction of a powder house. This was the beginning of a building tradition that extended into the 1930s along Florida's Atlantic Coast. In the St. Augustine vicinity, the Castillo de San Marcos, Fort Matanzas, the old city gates, the
Cathedral A cathedral is a church that contains the ''cathedra'' () of a bishop, thus serving as the central church of a diocese, conference, or episcopate. Churches with the function of "cathedral" are usually specific to those Christian denominations ...
, Spanish and British Period residential structures, property line walls and tombs were constructed of coquina quarried on Anastasia Island. To the south in New Smyrna, a large storehouse and wharf were constructed of coquina at the 1770s Andrew Turnbull colony. Around 1816, John Addison constructed a kitchen house of coquina on his plantation on the Tomoka River. The material was also used in the construction of sugar mill buildings on sugar plantations in the 1820s and 1830s. Examples are the Bulow, Dunlawton and New Smyrna sugar mills. In these early structures, the porous coquina was protected by lime plaster. With the exception of a few residences that have been restored in St. Augustine, the coquina masonry of these structures is today exposed to the elements and is slowly deteriorating.


Mexico

Overlying the fossiliferous sands and sandy clays of the upper
San Fernando River The San Fernando River is a river of Mexico. See also *List of longest rivers of Mexico *List of rivers of Mexico This is a list of rivers of Mexico, listed from north to south. There are 246 rivers on this list. Alternate names for rivers are gi ...
in northeastern Mexico is a bed of coquina limestone dating probably to the
Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...
era. Coquina deposits also occur in the
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
peninsula, including submerged "reefs". So-called coquina "reefs" occur at Punta Borrascosa, San Felipe and Coloraditos on the northeast coast of Baja California. These have been uranium-thorium dated to the Pleistocene epoch, with an age estimated at 130,000 ybp. Semi-continuous coquina outcrops have been found east of Puerto Peñasco, in the shallow subtidal zone or partly submerged under intertidal sands. Other Pleistocene outcrops occur along both coastlines of the upper
Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...
. On the Vizcaino Peninsula of western Baja California, the informally named " Tivela stultorum" coquina is abundant in shells of the Pismo clam. Until analysis of the shells by U-series and amino-acids methods is concluded, this marine transgression is assigned an approximate age of 200,000 ybp. Outcrops in Bahía de San Hipolito and Bahía de Asunción are loosely consolidated, sandy beachrock a few meters thick, found above present mean sea level. The ancient Maya built their city of Toniná in the highlands of what is now Chiapas in southern Mexico using native rocks to construct its masonry buildings, among them large coquina
flagstone Flagstone (flag) is a generic flat stone, sometimes cut in regular rectangular or square shape and usually used for paving slabs or walkways, patios, flooring, fences and roofing. It may be used for memorials, headstones, facades and other c ...
s from which they made blocks and bricks for floors, walls, and stairways.


North Carolina

Coquina has a very limited distribution in southeastern
North Carolina North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...
. The best known outcrop is located in New Hanover County, near Fort Fisher, along the southern tip of North Carolina's coast. It is one of the few naturally occurring outcrops in the coastal plain region of North Carolina, described as “a low-relief plain underlain by beds of shallow-marine, estuarine, shoreline, and fluvial sediments" in ''The Geology of the Carolinas''. These sediments were deposited during numerous episodes of sea level rise and fall over hundreds of thousands of years. The coastlines of the Tidewater region of North Carolina change constantly in response to wind and wave action, sedimentary deposition, tidal movements, and changes in sea level. Although the inner coastal plain is considered to be more stable, the coastal plain was inundated by repeated marine transgressions due to fluctuating sea levels during the late
Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Clear Springs Plantation near New Bern. Sedgeley Abbey, an 18th-century plantation house on the lower
Cape Fear River The Cape Fear River is a long blackwater river in east central North Carolina. It flows into the Atlantic Ocean near Cape Fear, from which it takes its name. The river is formed at the confluence of the Haw River and the Deep River (North Caro ...
was built of locally quarried coquina. The house that once stood on a vast tract of land directly across the river from Orton was described by local historian and author James Sprunt as "the grandest colonial residence of the Cape Fear". Sprunt compared Sedgeley Abbey in dimensions and appearance to the two-story, cellared, Governor Dudley mansion that still stands in Wilmington. Like many southern plantations, Sedgeley Abbey was abandoned after the
Civil War A civil war or intrastate war is a war between organized groups within the same state (or country). The aim of one side may be to take control of the country or a region, to achieve independence for a region, or to change government polici ...
. The vacant house was demolished in the 1870s and the coquina rubble was burned and spread on the fields as fertilizer. A cellar eight feet deep carved into solid coquina was located during archaeological investigations on the site of the former
plantation A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. Th ...
in 1978.


Other uses

In the past coquina was used for the construction of buildings in Denham, Western Australia, but quarrying is no longer permitted in the
World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...
. When first quarried, coquina is extremely soft. This softness makes it very easy to remove from the quarry and cut into shape. However, the stone is also at first much too soft to be used for building. In order to be used as a building material, the stone is left out to dry for approximately one to three years, which causes the stone to harden into a usable, but still comparatively soft, form. Coquina has also been used as a source of paving material. It is usually poorly cemented and easily breaks into component shell or coral fragments, which can be substituted for gravel or crushed harder rocks. In the 1930s, large-scale mining of coquina for use in highway construction began at Fort Fisher in North Carolina. Large pieces of coquina of unusual shape are sometimes used as landscape decoration. Because coquina often includes a component of phosphate, it is sometimes mined for use as
fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
.


Notable exposures

* Blowing Rocks Preserve (and along Country Club Road), Palm Beach County, Florida * Kure Beach, New Hanover County, North Carolina * Much Wenlock Limestone Formation,
Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to ...
, England * Odessa Catacombs,
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inva ...
* Shell Beach, Shark Bay, Western Australia * Washington Oaks State Gardens, Flagler County, Florida


In architecture

*
Bok Tower BOK Tower (named for the Bank of Oklahoma; formerly known as One Williams Center) is a skyscraper in Downtown Tulsa, Oklahoma. At 203 m (667 ft) in height, the 52-story tower was the tallest building in Oklahoma until surpassed by Dev ...
, Florida * Castillo de San Marcos,
St. Augustine, Florida St. Augustine ( ; es, San Agustín ) is a city in the Southeastern United States and the county seat of St. Johns County on the Atlantic coast of northeastern Florida. Founded in 1565 by Spanish explorers, it is the oldest continuously inhabi ...
* Fort Matanzas National Monument, Florida *
North Carolina Aquarium at Fort Fisher North Carolina Aquariums is a system of three public aquariums located in Kure Beach, Roanoke Island and Pine Knoll Shores. All are operated by the Aquariums Division of the North Carolina Department of Natural and Cultural Resources since 1976 ...
, displays a "Coquina Outcrop Touch Pool"


See also

* * * * Shelly Limestone - Type of Sedimentary Rock


References


External links

* {{Authority control Limestone Geology of Florida