The Anastasia Formation is a geologic formation

Geologic formation

A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a certain number of rock strata that have a comparable lithology, facies or other similar properties...

 deposited in Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 during the Late Pleistocene

Late Pleistocene

The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...

 epoch.

Age

Period : Quaternary

Quaternary

The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...

Epoch

Epoch (geology)

An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...

: Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 ~2.558 to 0.012 mya, calculates to a period of

Faunal stage: Blancan

Blancan

The Blancan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 4,750,000 to 1,808,000 years BP, a period of .. It is usually considered to start in the early-mid Pliocene epoch and end...

 through early Rancholabrean

Rancholabrean

The Rancholabrean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from less than 240,000 years to 11,000 years BP, a period of . It is usually considered to overlap the Middle Pleistocene...

Location

Anastasia Formation overlays the The Atlantic Coastal Ridge along the coast from St. John's County

St. Johns County, Florida

St. Johns County is a county located in northeastern Florida. As of the 2010 census, the population was 190,039. The county seat is St. Augustine. Due to the inclusion of Ponte Vedra Beach, it is one of the highest-income counties in the United States....

 southward to Palm Beach County

Palm Beach County, Florida

Palm Beach County is the largest county in the state of Florida in total area, and third in population. As of 2010, the county's estimated population was 1,320,134, making it the twenty-eighth most populous in the United States...

 and extends inland as far as 20 miles (32 kilometers) in St. Lucie

St. Lucie County, Florida

St. Lucie County is a county located in the state of Florida. The county seat is the city of Fort Pierce. In the year 2000, the population was 192,695. As of the year 2010, the United States Census Bureau sets the population at 277,789.- History :...

 and Martin County

Martin County, Florida

Martin County is a county in the U.S. state of Florida. As of 2000, the population was 126,731. The U.S. Census Bureau 2008 estimate for the county is 138,660. Its county seat is Stuart, Florida.- History :...

. Blowing Rocks Preserve

Blowing Rocks Preserve

Blowing Rocks Preserve is an environmental preserve on Jupiter Island in Hobe Sound, Martin County, Florida, USA. It is owned by The Nature Conservancy. It contains the largest Anastasia limestone outcropping on the state's east coast. The preserve also features several coastal ecotones, including...

 in northern Palm Beach County is an exposed outcropping along the beach.

Composition

The Anastasia Formation, named by E. H. Sellards in 1912, is composed of interbedded sands and coquina limestones

Coquina

Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of the shells of either molluscs, trilobites, brachiopods, or other invertebrates. For a sediment to be considered to be a coquina, the average size of the...

. The formation is an orangish brown, soft to moderately hard, coquina of whole and fragmented mollusk shells within sand often cemented by sparry calcite

Calcite

Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...

. Coquina obtained from this formation on Anastasia Island

Anastasia Island

Anastasia Island is a barrier island which is approximately long located off the northeast Atlantic coast of Florida in the United States. The island is located east and southeast of St. Augustine. It is separated from the mainland by the Matanzas River, part of the Intracoastal waterway, Matanzas...

 was used to construct Castillo de San Marcos

Castillo de San Marcos

The Castillo de San Marcos site is the oldest masonry fort in the United States. It is located in the city of St. Augustine, Florida. Construction was begun in 1672 by the Spanish when Florida was a Spanish territory. During the twenty year period of British possession from 1763 until 1784, the...

 during the late 17th century; a local material, it was relatively easy to quarry and proved to be effective for absorbing cannon

Cannon

A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...

 damage. Sands occur as fossil bearing light gray to tan as well as orangish brown, unconsolidated to moderately indurated. This formation is an integral part of the surficial aquifer

Surficial aquifer

Surficial aquifers are shallow aquifers typically less than 50 feet , but thicknesses of about have been mapped.- Composition :Surficial aquifers system consists mostly of beds of unconsolidated sand, cavity-riddled limestone and shells, sandstone, sand, and clay sand with minor clay or silt from...

system.