Coquina

Coquina (/koʊˈkiːnə/) is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of mollusks, trilobites, brachiopods, or other invertebrates.

Incompletely consolidated and poorly cemented coquinas are considered grainstones in the Dunham classification system for carbonate sedimentary rocks.

[6] 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.

The high-energy marine or lacustrine environments associated with coquinas include beaches, shallow submarine raised banks, swift tidal channels, and barrier bars.

The shell deposit, between 8 and 9 metres (26 and 30 ft) 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.

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.

[10] 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.

[11] 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.

[13] Pre-salt stratigraphy of the Santos Basin shows lacustrine sediments composed of coarse pelecypod (bivalve) coquina during the Barremian and Aptian sag phase of the continental crust subsidence.

In the St. Augustine vicinity, the Castillo de San Marcos, Fort Matanzas, the old city gates, the Cathedral, Spanish and British Period residential structures, property line walls and tombs were constructed of coquina quarried on Anastasia Island.

[16] Overlying the fossiliferous sands and sandy clays of the upper San Fernando River in northeastern Mexico is a bed of coquina limestone dating probably to the Cenozoic era.

Semi-continuous coquina outcrops have been found 13 kilometres (8.1 mi) east of Puerto Peñasco, in the shallow subtidal zone or partly submerged under intertidal sands.

On the Vizcaino Peninsula of western Baja California, the informally named "Tivela stultorum" coquina is abundant in shells of the Pismo clam.

[18][19] 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 flagstones from which they made blocks and bricks for floors, walls, and stairways.

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".