The Tully Formation is a geologic unit in the Appalachian Basin. The Tully was deposited as a carbonate rich mud, in a shallow sea at the end of the Middle Devonian.[1] Outcrops for the Tully are found in New York State and Pennsylvania.[2] It is also found subsurface in western Maryland and northern West Virginia. A number of fossil remains from marine organisms maybe found in Tully out crops.

Tully Formation
Stratigraphic range: Devonian
Tully Formation at Taughannock Falls State Park
TypeFormation
Sub-units
New York
  • New Lisbon Member
  • Laurens Member
  • West Brook Member
Pennsylvania
  • Weissport Member
  • Brodhead Creek Member
  • Lehighton Member
UnderliesHarrell Shale/Genesee Group
OverliesHamilton Group
Lithology
PrimaryLimestone
OtherShale, Siltstone, and Sandstone
Location
Region Maryland
 New York
 Pennsylvania
 West Virginia
CountryUnited States
Canada
Type section
Named forTully, NY
Named byVanuxem (1839)

Description

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The Tully is primary made up of limestone. There there are also layers with much higher clay contend resulting in a calcareous shale. To the east the Tully becomes siliciclastic. This is due to sediments being washed in from the Acadian Mountains to the east. By the time the Tully was being deposited the Appalachian Basin had been nearly filled in that the Tully was deposited on a broad planform of rock.[3] The Tully ranges in thickness to less than 1' in western New York to 70'+ thick in central Pennsylvania and 90'+ thick in southwestern Pennsylvania and northern West Virginia.

Fossils

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Brachiopods

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Tullypothyridina, Camarotoechia Mesocostale, Rhyssochonetes, Emanuella, Pseudoatrypa, Spinatrypa, Tylothyris, Mucrospirifer tulliensis, Cyrtina, Tullypothyridina, Echinocoelia, Strophodonta

References

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  1. ^ Philip H. Heckel (1963). "Depositional Environment of the Devonian Tully Limestone of Central New York: ABSTRACT". AAPG Bulletin. 47. doi:10.1306/bc7439df-16be-11d7-8645000102c1865d. ISSN 0149-1423.
  2. ^ Stevenson, R. E; Skinner, W. S. (1949). "The Tully Clastics of New York and Pennsylvania". Pennsylvania Academy of Science. 23: 28–33. JSTOR 44109398.
  3. ^ Baird, G.C.; Zambito, J.J.; Brett, C.E. (2012). "Genesis of unusual lithologies associated with the Late Middle Devonian Taghanic biocrisis in the type Taghanic succession of New York State and Pennsylvania". Palaeogeography, Palaeoclimatology, Palaeoecology. 367–368: 121–136. Bibcode:2012PPP...367..121B. doi:10.1016/j.palaeo.2011.11.010. ISSN 0031-0182.