The Aquia Formation is a geologic

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

formation that extends from the upper

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the ...

to the

James River The James River is a river in the U.S. state of Virginia that begins in the Appalachian Mountains and flows U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed April 1, 2011 to Ches ...

near

Hopewell, Virginia Hopewell is an independent city surrounded by Prince George County and the Appomattox River in the Commonwealth of Virginia. At the 2020 census, the population was 23,033. The Bureau of Economic Analysis combines the city of Hopewell with ...

. It consists of clayey, silty, very shelly, glauconitic sand.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

records indicate that this

stratigraphic unit A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize ...

was created during the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

. The Aquia formation was named for

Aquia Creek Aquia Creek () is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed August 15, 2011 tributary of the tidal segment of the Potomac River and is located in northern Virginia. The creek's h ...

where it is exposed in cliff faces along the banks.

Geology

Lithology

When uncovered, it appears dark green to gray-green,

argillaceous Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay mineral ...

, with well sorted fine- to medium-grained sand and locally indurated shell beds. It is between 0 and 100 feet thick in Maryland.

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 ...

and phosphatic pebbles and/or very coarse glauconitic quartz sand mark the base of the unit. A few hard streaks of shells or thin "rock" layers are often reported but appear to be more abundant in the sections south of the James River.

Stratigraphy

The Aquia formation is overlain by the Nanjemoy Formation and overlies the

Brightseat Formation The Brightseat Formation is an exposure of marine sedimentary rock beds of Upper Cretaceous/Lower Paleocene age (65 MY to 55.5 MY), in Landover, Maryland. The exposure is located at Brightseat Road between Sheriff and Landover Roads. The site is cur ...

. The Aquia formation is broken down into two members: the lower Piscataway member and upper Paspotansa member.

Age

The Aquia Formation is thought to be 59.0-55.5 million years old. The Piscataway member is 59-56.25 million years old, and the Paspotansa member is 56-55.5 million years old. This is the

period. Older publications describe the Aquia as being of

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

age.

Fossils

Vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, wi ...

Bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartila ...

*''

Lepisosteus ''Lepisosteus'' is a genus of gars in the family Lepisosteidae. Distribution While in the present day, ''Lepisosteus'' is only known across North America, fossil remains show it was much more widespread in the past, with specimens known from ...

''Phatfossil
Aquia Formation
in Maryland and Virginia *'' Ostracion'' *''

Phyllodus ''Phyllodus'' is an extinct genus of bony fish from the Maastrichtian to Middle Miocene. Fossils of the genus have been found in the Maastrichtian to Lancian Hell Creek Formation and the Eocene London Clay. See also * List of prehistoric bony ...

'' *'' Scomberomorus'' *''Labridae'' (

Wrasse The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into 9 subgroups or tribes. They are typically small, most of them ...

)

Chondrichthyes Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissu ...

=
Sharks Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

= *''

Abdounia ''Abdounia'' is an extinct genus of requiem shark which lived during the Paleogene period. It is mainly known from isolated teeth. It is one of the earliest requiem sharks, and attained widespread success in North America, Europe, and Africa. Lo ...

beaugei'' *''

Anomotodon ''Anomotodon'' is an extinct genus of shark related to the extant goblin shark (''Mitsukurina owstoni''). The distribution of ''Anomotodon'' fossils is worldwide, in formations indicating that members of the genus lived from the Early Cretaceous ...

novus'' *''

Carcharias ''Carcharias'' is a genus of sand tiger sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark. Description ''Carcharias'' ar ...

hopei'' *''

Cretolamna ''Cretalamna'' is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch (about 103 to 46 million years ago). It is considered by many to be the ancestor of the largest sharks to have ever lived, '' Otodu ...

appendiculata'' *'' Delpitoscyllium africanum'' *'' Foumtizia abdouni'' *'' Galeorhinus'' *''

Ginglymostoma ''Ginglymostoma'' is a genus of shark in the family Ginglymostomatidae. There are two members in the genus. Members of this genus eat small fish and crustaceans, and are commonly quite lethargic unless provoked. Members of this genus have the abi ...

subafricanum'' *'' Heterodontus lerichei'' *'' Hypotodus verticalis'' *'' Isurolamna inflata'' *'' Megasqualus orpiensis'' *'' Notidanodon loozi'' *'' Odontaspisx loozi'' *'' Orectolobiform'' *'' Otodus obliquus'' *'' Pachygaleus lefevrei'' *'' Palaeogaleus'' *'' Paleocarcharodon orientalis'' *'' Paleohypotodus rutoti'' *''

Paraorthacodus ''Paraorthacodus'' is an extinct genus of cartilaginous fish. An unidentified species has been found in the Hasle Formation of Bornholm Bornholm () is a Danish island in the Baltic Sea, to the east of the rest of Denmark, south of Sweden, no ...

clarkii'' *'' Physogaleus secundus'' *'' Premontreia subulidens'' *'' Scyliorhinus'' *''

Squalus ''Squalus'' is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper ...

'' *'' Squatina prima'' *''

Striatolamia ''Striatolamia'' is an extinct genus of sharks belonging to the family Odontaspididae. These extinct sharks lived from the Early Paleocene to Late Miocene (61.7 to 10.3 Ma). Etymology The Latin genus name ''Striatolamia'' refers to the striati ...

macrota'' *''

striata'' *'' Triakis''

= Rays

= *''

Myliobatis ''Myliobatis'' is a genus of eagle rays in the family Myliobatidae. Description ''Myliobatis'' species can reach a width up to about . Their bodies consist of a rhomboidal disc, wider than long, with one dorsal fin. The head is broad and short, ...

'' *'' Burnhamia'' *''

Coupatezia ''Coupatezia'' is a prehistoric genus of ray in the family Dasyatidae whose fossils are found in strata dating from the Maastrichtian stage until the last species' extinction during the Middle Eocene. These rays were found shallow seas in Eur ...

soutersi'' *''

Dasyatis ''Dasyatis'' (Greek δασύς ''dasýs'' meaning rough or dense and βατίς ''batís'' meaning skate) is a genus of stingray in the family Dasyatidae that is native to the Atlantic, including the Mediterranean. In a 2016 taxonomic revisi ...

'' *'' Hypolophodon sylvestris'' *'' Ischyodusx sylvestris''

Reptiles Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephali ...

=
Crocodylians Crocodilia (or Crocodylia, both ) is an Order (biology), order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous Period (geology), period (Cenomanian St ...

= *'' Eosuchus'' *''

Hyposaurus ''Hyposaurus'' is a genus of extinct marine dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Iullemmeden Basin in West Africa, Campanian–Maastrichtian (Late Cretaceous) Shendi Formation of Sudan and Maastri ...

'' *'' Thecachampsa'' *'' Thoracosaurus''

=
Turtles 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 ...

= *'' Trionyx''

Mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fu ...

Mammal fossils are extremely rare.

Birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

Bird fossils are extremely rare.

Molluscs 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 esti ...

Gastropods The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

*''

Turritella ''Turritella'' is a genus of medium-sized sea snails with an Operculum (gastropod), operculum, marine (ocean), marine gastropod mollusc, mollusks in the family Turritellidae.Vos, C.; Gofas, S. (2013). Turritella Lamarck, 1799. Accessed through: W ...

'' is very common. *''Pleurotoma potomacensis''

Bivalves 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, biv ...

*'' Crassatelites alaeformis'' *'' Cucullaea gigantea'' *'' Dosiniopsis lenticularis'' *'' Meretrix ovata'' *'' Modiolus alabamensis'' * ''Ostrea'' compressirostra *''

Panopea In Greek mythology, Panopea ( Ancient Greek: Πανόπεια ''Panopeia'') or Panope (Πανόπη) may refer to various characters. The names mean 'panorama' or means 'of the beautiful husband'. * Panope or Poenope, Hyginus, ''Fabulae'' Prefac ...

elongata'' *''

Venericardia ''Venericardia'' is a widely distributed genus of marine bivalve molluscs, in the family Carditidae. It is the type genus of subfamily Venericardiinae. The closely related '' Purpurocardia'' was for long included here as a subgenus In biol ...

planicosta'' *'' Vulsella alabamensis''

Cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

*'' Cimomia marylandensis'' is present but uncommon.

References

{{reflist Geologic formations of Maryland Geologic formations of New Jersey Geologic formations of Virginia Paleocene Series of North America Paleogene Maryland Paleogene geology of New Jersey Paleogene geology of Virginia Thanetian Stage Sandstone formations of the United States