Aquia Formation

Aquia Formation
Stratigraphic range: Late Paleocene ~59.0–55.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Boulder of Aquia Formation along Chester River. Contains casts of large mollusks. (c. 1917)
Type	Geological formation
Unit of	Pamunkey Group
Sub-units	Paspotansa & Piscataway Members
Underlies	Nanjemoy Formation
Overlies	Brightseat Formation
Thickness	up to 100 feet (30 m)
Lithology
Primary	Sandstone
Location
Location	Hopewell, Virginia
Coordinates	38.3°N 77.3°W / 38.3; -77.3
Approximate paleocoordinates	39.0°N 58.9°W / 39.0; -58.9
Region	Maryland, New Jersey, Virginia
Country	United States
Extent	Upper Chesapeake Bay-James River
Type section
Named for	Aquia Creek

Thecachampsa crocodile coprolite from Aquia Formation, King George County, Virginia)

The Aquia Formation is a geologic sandstone formation that extends from the upper Chesapeake Bay to the James River near Hopewell, Virginia.[1] It consists of clayey, silty, very shelly, glauconitic sand.[1] Fossil records indicate that this stratigraphic unit was created during the Paleocene.[1]

The Aquia formation was named for Aquia Creek where it is exposed in cliff faces along the banks.[2]

Geology

Lithology

When uncovered, it appears dark green to gray-green, argillaceous, with well sorted fine- to medium-grained sand and locally indurated shell beds.[3] It is between 0 and 100 feet thick in Maryland.[3] Quartz and phosphatic pebbles and/or very coarse glauconitic quartz sand mark the base of the unit.[4] 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.[4]

Stratigraphy

The Aquia formation is overlain by the Nanjemoy Formation and overlies the Brightseat Formation.[5]

The Aquia formation is broken down into two members: the lower Piscataway member and upper Paspotansa member.[2]

Age

The Aquia Formation is thought to be 59.0-55.5 million years old.[2] The Piscataway member is 59–56.25 million years old, and the Paspotansa member is 56–55.5 million years old.[2] This is the Paleocene period.

Older publications describe the Aquia as being of Eocene age.[6]

Fossils

Vertebrates

Bony fish

• Lepisosteus[2]
• Ostracion[2]
• Phyllodus[2]
• Scomberomorus[2]
• Labridae (Wrasse)[2]

Chondrichthyes

Sharks

• Abdounia beaugei[2][7]
• Anomotodon novus[2][8]
• Carcharias hopei[2][8]
• Cretolamna appendiculata[2][8]
• Delpitoscyllium africanum[2]
• Foumtizia abdouni[2]
• Galeorhinus[2]
• Ginglymostoma subafricanum[2]
• Heterodontus lerichei[2]
• Hypotodus verticalis[2]
• Isurolamna inflata[2]
• Megasqualus orpiensis[2]
• Notidanodon loozi[2]
• Odontaspisx loozi[2]
• Orectolobiform[2]
• Otodus obliquus[2][9][8]
• Pachygaleus lefevrei[2]
• Palaeogaleus[2]
• Paleocarcharodon orientalis[2][9][8]
• Paleohypotodus rutoti[2][10]
• Paraorthacodus clarkii[2]
• Physogaleus secundus[11]
• Premontreia subulidens[2]
• Scyliorhinus[2]
• Squalus
• Squatina prima[2]
• Striatolamia macrota[2][8]
• Striatolamia striata[2]
• Triakis[2]

Rays

• Myliobatis[12]
• Burnhamia[2]
• Coupatezia soutersi[2]
• Dasyatis[2]
• Hypolophodon sylvestris[2]
• Ischyodusx sylvestris[2]

Reptiles

Crocodylians

• Eosuchus[8]
• Hyposaurus[8]
• Thecachampsa[13]
• Thoracosaurus[8]

Turtles

• Trionyx[8][14]

Mammals

Mammal fossils are extremely rare.[2]

Birds

Bird fossils are extremely rare.[2]

Molluscs

Gastropods

• Turritella is very common.[2][8][15]
• Pleurotoma potomacensis[16]

Bivalves

• Crassatelites alaeformis[16]
• Cucullaea gigantea[17][16][18]
• Dosiniopsis lenticularis[16]
• Meretrix ovata[16]
• Modiolus alabamensis[16]
• Ostrea compressirostra[19][16]
• Panopea elongata[16]
• Venericardia planicosta[16]
• Vulsella alabamensis[19]

Cephalopods

• Cimomia marylandensis is present but uncommon.[20]

See also

• List of fossiliferous stratigraphic units in Virginia
• Paleontology in Virginia
• Aquia Creek sandstone
• Public Quarry at Government Island

References

1. Geology of the National Capital Region - Field Trip Guidebook. Reston, Virginia: U.S. Geological Survey, Department of the Interior. 2004. p. 270.
2. Phatfossils Aquia Formation in Maryland and Virginia
3. "Coastal Plain Rocks and Sediments". Geological Maps of Maryland. Maryland Geological Survey. 1968. Retrieved 21 January 2015.
4. Powars, D.S.; Bruce, T.S. (2000). The Effects Of The Chesapeake Bay Impact Crater On The Geological Framework And Correlation Of Hydrogeologic Units Of The Lower York-James Peninsula, Virginia. United States Geological Survey. Retrieved 22 January 2015.
5. Page, Richard A (1959). "The Questionable Age of the Aquia Formation". Journal of Paleontology. 33 (2): 347–350. JSTOR 1300764.
6. Tolchester folio, Maryland, Folios of the Geologic Atlas 204, by B. L. Miller, E. B. Mathews, A. B. Bibbins, and H. P. Little, 1917.
7. Elasmo.com, The Life and Times of Long Dead Sharks, Abdounia, Jim Bourdon, author.
8. "Fossil Identification for the Potomac River".
9. "Potomac - Aquia Formation 3/15/18".
10. "Paleohypotodus?".
11. "Physogaleus secundus".
12. "Myliobatis".
13. "Thecachampsa".
14. "Trionyx".
15. "Turritella sp".
16. Virginia Division of Mineral Resources (1912). Bulletin. p. 200. fossils of the aquia formation.
17. "Cucullaea Gigantea". 15 May 2010.
18. "Views of the Mahantango: Cucullaea gigantea pelecypod from the Aquia Formation". 11 August 2014.
19. "Ostrea compressirostra".
20. "Sanity check: It's a Nautilus, right?".