Coquina

Photographed by Michael P. Klimetz

Peace River Formation

Miocene

Peace River

Arcadia

FLORIDA

Photographed by Michael P. Klimetz

Decorah Formation

Ordovician

St. Paul

MINNESOTA

Photographed by Michael P. Klimetz

Pleistocene

Anastasia Formation

Ormond Beach

Volusia County

FLORIDA

Photographed by Michael P. Klimetz

Pleistocene

Anastasia Formation

Ormond Beach

Volusia County

FLORIDA

Photographed by Michael P. Klimetz

Pleistocene

Anastasia Formation

Ormond Beach

Volusia County

FLORIDA

Coquina is a sedimentary rock that is composed either wholly or almost entirely of transported, abraded, mechanically sorted, and cemented fragments of shells of either molluscs, trilobites, brachiopods, or other invertebrates. To be considered to be a coquina, the average size of the particles composing it must be in excess of 0.2 cm. Coquina can vary in lithification from poorly to moderately-cemented. The term "coquina" is derived from the Spanish word for cockleshells or shellfish. Coquinas accumulate in high-energy marine and lacustrine environments where currents and waves result in the vigorous winnowing, abrasion, fracturing, and sorting of component shells. As a result, they typically exhibit well-developed bedding or cross-bedding, close packing, and parallel orientation of shell fragments. The high-energy marine or lacustrine environments associated with coquinas include beaches, shallow submarine raised banks, swift tidal channels, and barrier bars. Mineralogically, coquina is mainly composed of calcite, often including some phosphate compounds, in the form of shell matter or coral. Coquinas ranging from Ordovician to Pleistocene are common worldwide.

Photographed by Michael P. Klimetz

Crinoidal Biosparudite

Ectenocrinus sp.

Late Ordovician

Nashville Group

Hermitage Formation

Lynchburg

Moore County

TENNESSEE

Photographed by Michael P. Klimetz

Crinoidal Biosparudite

Ectenocrinus sp.

Late Ordovician

Nashville Group

Hermitage Formation

Lynchburg

Moore County

TENNESSEE