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Aquia FormationStratigraphic range: Late Paleocene~59.0–55.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Thecachampsa crocodile coprolite (Aquia Formation, Upper Paleocene; Potomac River shores, King George County, northeastern Virginia, USA).jpg
Thecachampsa crocodile coprolite (Aquia Formation; King George County, Virginia)
TypeGeological formation
Unit ofPamunkey Group
Sub-unitsPaspotansa & Piscataway Members
UnderliesNanjemoy Formation
OverliesBrightseat Formation
Thicknessup to 100 feet (30 m)
Lithology
PrimarySandstone
Location
LocationHopewell, Virginia
Coordinates38°18′N 77°18′W / 38.3°N 77.3°W / 38.3; -77.3Coordinates: 38°18′N 77°18′W / 38.3°N 77.3°W / 38.3; -77.3
Approximate paleocoordinates39°00′N 58°54′W / 39.0°N 58.9°W / 39.0; -58.9
RegionMaryland, New Jersey, Virginia
Country United States
ExtentUpper Chesapeake Bay-James River
Type section
Named forAquia Creek

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[edit]

Lithology[edit]

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 occurs between 0 and 100 feet thick.[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[edit]

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[edit]

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]

Fossils[edit]

Vertebrates[edit]

Bony fish[edit]

  • Lepisosteus[2]
  • Ostracion[2]
  • Phyllodus[2]
  • Scomberomorus[2]
  • Wrasse[2]

Chondrichthyes[edit]

Sharks[edit]
  • Abdounia beaugei[2][6]
  • Anomotodon novus[2][7]
  • Carcharias hopei[2][7]
  • Cretolamna appendiculata[2][7]
  • 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][8][7]
  • Pachygaleus lefevrei[2]
  • Palaeogaleus[2]
  • Paleocarcharodon orientalis[2][8][7]
  • Paleohypotodus rutoti[2][9]
  • Paraorthacodus clarkii[2]
  • Physogaleus secundus[10]
  • Premontreia subulidens[2]
  • Scyliorhinus[2]
  • Squalus
  • Squatina prima[2]
  • Striatolamia macrota[2][7]
  • Striatolamia striata[2]
  • Triakis[2]
Rays[edit]
  • Myliobatis[11]
  • Burnhamia[2]
  • Coupatezia soutersi[2]
  • Dasyatis[2]
  • Hypolophodon sylvestris[2]
  • Ischyodusx sylvestris[2]

Reptiles[edit]

Crocodylians[edit]
  • Eosuchus[7]
  • Hyposaurus[7]
  • Thecachampsa[12]
  • Thoracosaurus[7]
Turtles[edit]
  • Trionyx[7][13]

Mammals[edit]

Mammal fossils are extremely rare.[2]

Birds[edit]

Bird fossils are extremely rare.[2]

Molluscs[edit]

Gastropods[edit]

  • Turritella is very common.[2][7][14]
  • Pleurotoma potomacensis[15]

Bivalves[edit]

  • Crassatelites alaeformis[15]
  • Cucullaea gigantea[16][15][17]
  • Dosiniopsis lenticularis[15]
  • Meretrix ovata[15]
  • Modiolus alabamensis[15]
  • Ostrea compressirostra[18][15]
  • Panopea elongata[15]
  • Venericardia planicosta[15]
  • Volsella alabamensis[18]

Cephalopods[edit]

  • Cimomia marylandensis is present but uncommon.[19]

See also[edit]

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

References[edit]

  1. ^ a b c Geology of the National Capital Region - Field Trip Guidebook. Reston, Virginia: U.S. Geological Survey, Department of the Interior. 2004. p. 270.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar http://phatfossils.com/Aquia%20Formation%20Paleocene%20of%20Maryland%20and%20Virginia.php
  3. ^ a b "Coastal Plain Rocks and Sediments". Geological Maps of Maryland. Maryland Geological Survey. 1968. Retrieved 21 January 2015. CS1 maint: discouraged parameter (link)
  4. ^ a b 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. CS1 maint: discouraged parameter (link)
  5. ^ Page, Richard A (1959). "The Questionable Age of the Aquia Formation". Journal of Paleontology. 33 (2): 347–350. JSTOR 1300764.
  6. ^ http://www.elasmo.com/frameMe.html?file=genera/cenozoic/sharks/abdounia.html&menu=bin/menu_genera-alt.html
  7. ^ a b c d e f g h i j k http://www.fossilguy.com/sites/potomac/liv_col.htm
  8. ^ a b http://www.thefossilforum.com/index.php?/topic/82854-potomac-aquia-formation-31518/
  9. ^ http://www.thefossilforum.com/index.php?/topic/83055-paleohypotodus/
  10. ^ http://www.itano.net/fossils/marylan2/galeo1s.htm
  11. ^ http://www.itano.net/fossils/marylan2/mylio1s.htm
  12. ^ http://www.itano.net/fossils/marylan2/theca1s.htm
  13. ^ http://www.itano.net/fossils/marylan2/trion1s.htm
  14. ^ http://www.itano.net/fossils/marylan2/turr1s.htm
  15. ^ a b c d e f g h i Virginia Division of Mineral Resources (1912). Bulletin. p. 200. fossils of the aquia formation.
  16. ^ https://iapetancaptain.wordpress.com/2010/05/15/cucullaea-gigantea/
  17. ^ http://viewsofthemahantango.blogspot.com/2014/08/cucullaea-gigantea-pelecypod-from-aquia.html
  18. ^ a b http://www.itano.net/fossils/marylan2/ostre1s.htm
  19. ^ http://www.thefossilforum.com/index.php?/topic/84977-sanity-check-its-a-nautilus-right/