The Permian Dunkard Group (Pd) is an area of rock, Early Permian in age, in the south of Ohio, southwestern Pennsylvania, West Virginia and the hilltops of the Georges Creek Basin of Maryland.[2] In Ohio, it is found primarily in Washington County. It is notable for being one of the few areas of Permian sediment east of the Mississippi River. In addition, it is the youngest surface rock in the state of Ohio.

Dunkard Group
Stratigraphic range: Pennsylvanian-Permian
Sandstone (Greene Formation, Dunkard Group, Lower Permian; Monroe County, Ohio)
TypeGroup
Sub-unitsGreene Formation, Washington Formation, Waynesburg Formation[1]
UnderliesIgneous intrusives
OverliesMonongahela Formation
Lithology
PrimaryShale, sandstone, siltstone, coal
OtherLimestone
Location
Region Ohio,  Pennsylvania,  West Virginia, and  Maryland
Country United States
Type section
Named forDunkard Creek
Named byI.C. White in 1891

Description edit

It consists of red and green shale, siltstone, and sandstone, with thin lenticular beds of argillaceous limestone and thin beds of impure coal The base of the layer contains thick-bedded, white conglomeratic sandstone. The layer's thickness is greater than 200 feet in Maryland.[2]

The fossils found in the Dunkard Group are similar to ones found in Texas and Oklahoma of similar age.

Stratigraphy edit

The Dunkard contains three formation. Starting at the base (oldest) is the Waynesburg Formation, Washington Formation, and Greene Formation. The base is marked by the Waynesburg Coal, with the Monongahela Group below. The Washington Coal is found at the base of the Washington Formation and its base marks the boundary between the lower Waynesburg and the Washington formation above. The top of the Upper Washington Limestone marks the line between the Washington Formation and the upper Greene formation.

Fossil content edit

Portrait Name
  Dimetrodon
  Ctenospondylus
  Archaeothyris
  Edaphosaurus
  Eryops
  Xenacanthus
  Ophiacodon
  Diploceraspis
  Protorothyris
  Diadectes
  Isodectes
  Brachydectes
  Phlegethontia
Baldwinonus
Sagenodus
Sysciophlebia balteata


References edit

  1. ^ Berryhill, Jr., Henry L.; Swanson, Vernon E. (1962). "Geological Survey research 1962; Short papers in geology and hydrology" (PDF). U.S. Geological Survey Professional Paper. 450-C: 43–46. Retrieved 30 June 2018.
  2. ^ a b "Allegheny Plateau and Valley and Ridge". Geologic Map of Maryland. Maryland Geological Survey. 1968. Retrieved 2008-01-26.

Further reading edit

  • Anstey, Robert L.; Feldmann, Rodney M.; Hackathorn, Merrianne (1996). Fossils of Ohio. Columbus: State of Ohio, Dept. of Natural Resources, Division of Geological Survey. ISBN 0-931079-05-5.