Aquia Formation

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Aquia Formation
Stratigraphic range: Late Paleocene
~59.0–55.5  Ma
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Tolchester folio Maryland Plate VI.jpg
Boulder of Aquia Formation along Chester River. Contains casts of large mollusks. (c. 1917)
Type Geological formation
Unit of Pamunkey Group
Sub-unitsPaspotansa & Piscataway Members
Underlies Nanjemoy Formation
Overlies Brightseat Formation
Thicknessup to 100 feet (30 m)
Lithology
Primary Sandstone
Location
Location Hopewell, Virginia
Coordinates 38°18′N77°18′W / 38.3°N 77.3°W / 38.3; -77.3
Approximate paleocoordinates 39°00′N58°54′W / 39.0°N 58.9°W / 39.0; -58.9
Region Maryland, New Jersey, Virginia
Country United States
ExtentUpper Chesapeake Bay-James River
Type section
Named for Aquia Creek
Thecachampsa crocodile coprolite from Aquia Formation, King George County, Virginia) Thecachampsa crocodile coprolite (Aquia Formation, Upper Paleocene; Potomac River shores, King George County, northeastern Virginia, USA).jpg
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]

Contents

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

Bony fish from the Aquia Formation
GenusSpeciesMaterialNotesImages
Lepisosteus [2] L.sp.A Gar fish
Ostracion [2] O.sp.An Ostraciid (Boxfish)
Phyllodus [2] P.sp.A bonefish
Scomberomorus [2] S.sp.A mackrel fish
Labridae [2] Labridae indet.A wrasse

Chondrichthyes

Sharks
Sharks from the Aquia Formation
GenusSpeciesMaterialNotesImages
Abdounia [2] [7] A.beaugeiA reqium shark
Abdounia beaugei.jpg
Anomotodon [2] [8] A.novusA goblin shark
Anomotodon novus.jpg
Carcharias [2] [8] C.hopeiA sand tiger shark
Cretolamna [2] [8] C.appendiculataA megatooth shark
MenuhaCretalamnaAppendiculata.jpg
Delpitoscyllium [2] D.africanum
Foumtizia [2] F.abdouni
Galeorhinus [2] G.sp.A houndshark
Ginglymostoma [2] G.subafricanumA nurse shark
Heterodontus [2] H.lericheiA bullhead shark
Hypotodus [2] H.verticalis
Isurolamna [2] I.inflataA mackrel shark
Megasqualus [2] M.orpiensis
Notidanodon [2] N.looziA cow shark
Odontaspisx [2] O.loozi
Orectolobiform [2] O. Indet.
Otodus [2] [9] [8] O.obliquusA Megatooth shark
Otodus obliquus.jpg
Pachygaleus [2] P.lefevrei
Palaeogaleus [2] P.sp.
Paleocarcharodon [2] [9] [8] P.orientalisA megatooth shark
Paleohypotodus [2] [10] P.rutoti
Paraorthacodus [2] P.clarkiiA Paraorthacodontid shark
Physogaleus [11] P.secundusA reqium shark
Premontreia [2] P.subulidens
Scyliorhinus [2] S.sp.A Scyliorhinid shark
Squalus S.sp.A dogfish
Squatina [2] S.primaAn Angel shark
Striatolamia [2] [8] S.macrotaA Sand shark
S.striata
Triakis [2] T.sp.A Houndshark
Rays
Rays from the Aquia Formation
GenusSpeciesMaterialNotesImages
Myliobatis [12] M.sp.A Mylobatiform ray
Burnhamia [2] B.sp.A devil ray
Coupatezia C. soutersi [2] A dasyatid ray
Dasyatis [2] D.sp
Hypolophodon H.sylvestris [2]
Ischyodusx I. sylvestris [2]

Reptiles

Crocodylomorphs
Crocodylomorphs from the Aquia Formation
GenusSpeciesMaterialNotesImages
Eosuchus [8] E.sp.A eusuchian crocodylomorph
Hyposaurus [8] H.sp.A dyrosaurid
Thecachampsa [13] T.sp.A gavialoid crocodylian
Thoracosaurus [8] T.sp.A eusuchian crocodylomorph
Turtles
Turtles from the Aquia Formation
GenusSpeciesMaterialNotesImages
Trionyx [8] [14] T.sp.A softshell turtle

Molluscs

Gastropods

Gastropods from the Aquia Formation
GenusSpeciesMaterialNotesImages
Turritella [2] [8] [15] T.sp.very commonly found in the formation
Pleurotoma [16] P.potomacensis

Bivalves

Bivalves from the Aquia Formation
GenusSpeciesMaterialNotesImages
Crassatelites [16] C.alaeformis
Cucullaea [17] [16] [18] C.gigantea
Dosiniopsis [16] D.lenticularis
Meretrix (bivalve) [16] M.ovata
Modiolus (bivalve) [16] M.alabamensis
Ostrea [19] [16] O.compressirostra
Panopea [16] P.elongata
Venericardia [16] V.planicosta
Vulsella [19] V.alabamensis

Cephalopods

Sharks from the Aquia Formation
GenusSpeciesMaterialNotesImages
Cimomia [20] C.marylandensisUncommonly found

Mammal and bird fossils are also uncommonly found in the formation. [2]

See also

References

  1. 1 2 3 Geology of the National Capital Region - Field Trip Guidebook. Reston, Virginia: U.S. Geological Survey, Department of the Interior. 2004. p. 270.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Phatfossils Aquia Formation in Maryland and Virginia
  3. 1 2 "Coastal Plain Rocks and Sediments". Geological Maps of Maryland. Maryland Geological Survey. 1968. Retrieved 21 January 2015.
  4. 1 2 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. 1 2 3 4 5 6 7 8 9 10 11 "Fossil Identification for the Potomac River".
  9. 1 2 "Potomac - Aquia Formation 3/15/18".
  10. ↑ "Paleohypotodus?".
  11. ↑ "Physogaleus secundus".
  12. ↑ "Myliobatis".
  13. ↑ "Thecachampsa".
  14. ↑ "Trionyx".
  15. ↑ "Turritella sp".
  16. 1 2 3 4 5 6 7 8 9 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. 1 2 "Ostrea compressirostra".
  20. ↑ "Sanity check: It's a Nautilus, right?".
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