The Anastasia Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

deposited 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 to ...

during the Late Pleistocene epoch.

Age

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

: Quaternary

Epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological 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 finally confirmed in ...

~2.558 to 0.012 mya, calculates to a period of

Faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convent ...

: Blancan through early

Rancholabrean The Rancholabrean North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from less than 240,000 years to 11,000 years BP, a pe ...

Location

Anastasia Formation overlies the Atlantic Coastal Ridge along the coast from St. John's County southward to

Palm Beach County Palm Beach County is a county located in the southeastern part of Florida and lies directly north of Broward County and Miami-Dade County. The county had a population of 1,492,191 as of the 2020 census, making it the third-most populous county ...

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

Blowing Rocks Preserve Blowing Rocks Preserve is an environmental preserve on Jupiter Island in Hobe Sound Hobe Sound is an unincorporated area and census-designated place (CDP) in Martin County, Florida, United States, located along Florida's Treasure Coast. The po ...

in southern Martin County is an exposed outcropping along the beach.http://sofia.usgs.gov/publications/reports/mgs_lovejoy1998/ USGS Publications, Classic Exposures of the Anastasia Formation in Martin and Palm Beach Counties, Florida. A second outcropping is seen at

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 H ...

in northern Flagler County, south of St. Augustine.

History

The Anastasia Formation was named by E. H. Sellards in 1912. Coquina obtained from this formation on

Anastasia Island Anastasia Island is a barrier island located off the northeast Atlantic coast of Florida in the United States. It sits east of St. Augustine, running north–south in a slightly southeastern direction to Matanzas Inlet. The island is about long ...

was used to construct Castillo de San Marcos during the late 17th century; a local material, it was relatively easy to quarry and proved to be effective for absorbing

cannon A cannon is a large- caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder ...

damage. This formation is an integral part of the surficial aquifer system. Formed through multicyclic deposition the formation contains at least two disconformities, and two detectable ages. The formation registers in the late Pleistocene with oldest samples aging at 110,000 YBP based on radiometric dating (U²³⁴/Th²³⁰).

Composition

The Anastasia Formation is composed of

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

sands and calcite coquina, with sporadic instances of fossil debris. Coloration of the formation varies from a light grey tone to a soft orange-brown. The formation is soft to moderately hard coquina composed of whole and fragmented

mollusk 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 e ...

shells within sand often cemented by sparry calcite.USGS Publications, Lithostratigraphic Units, Tertiary System, Pleistocene Series
/ref> Sands occur as fossil-bearing light gray to tan as well as orange-brown, unconsolidated to moderately indurated. Fossils consist of both vertebral and invertebral species most of which are still present in the current epoch. Poriferans,

bryozoans 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 l ...

, mollusks, arthropods, and echinoderms have all been seen and recorded within the formation. Vertebrate taxa include cetacean,

testudines Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

, perissodactyla, and selachimorpha. Most fossils are highly fragmented with greatest preservation seen in the

in Martin County, and regions north of Palm Beach. Bioturbation is also seen in Palm Beach, Martin and Flagler counties. Large and small fossilized burrows formed by invertebrate species are seen in Palm Beach and Martin Counties whereas Flagler County sees large borings formed and fossilized around trees previously present in the area. The Formation is seen as a relevant portion of the

Biscayne Aquifer The Biscayne Aquifer, named after Biscayne Bay, is a surficial aquifer. It is a shallow layer of highly permeable limestone under a portion of South Florida. The area it underlies includes Broward County, Miami-Dade County, Monroe County, and P ...

. It is also an integral part of the surficial aquifer system in northern portions of Florida.

References

{{reflist Geologic formations of Florida Quaternary geologic formations Limestone formations Shallow marine deposits Paleontology in Florida