Aquia Formation

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]

Aquia Formation
Stratigraphic range: Paleogene (59.0-55.5 million years)
Thecachampsa crocodile coprolite (Aquia Formation; King George County, Virginia)
TypeGeological formation
UnderliesNanjemoy Formation
OverliesBrightseat Formation
Thicknessup to 100 feet (30 m)
Lithology
PrimarySandstone
Location
LocationHopewell, Virginia
CountryUnited States
Type section
Named forAquia Creek

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 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

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]

Fossils

Vertebrates

Bony fish

Chondrichthyes
Sharks
Rays

Reptiles
Crocodylians
Turtles

Mammals

Mammal fossils are extremely rare.[2]

Birds

Bird fossils are extremely rare.[2]

Molluscs

Gastropods

Bivalves

Cephalopods
  • Cimomia marylandensis is present but uncommon.[19]

See also

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. http://phatfossils.com/Aquia%20Formation%20Paleocene%20of%20Maryland%20and%20Virginia.php
  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. http://www.elasmo.com/frameMe.html?file=genera/cenozoic/sharks/abdounia.html&menu=bin/menu_genera-alt.html
  7. http://www.fossilguy.com/sites/potomac/liv_col.htm
  8. 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. 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. http://www.itano.net/fossils/marylan2/ostre1s.htm
  19. http://www.thefossilforum.com/index.php?/topic/84977-sanity-check-its-a-nautilus-right/
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