Dunkard Group
| Dunkard Group | |
|---|---|
| Stratigraphic range: Pennsylvanian-Permian | |
| File:Sandstone (Greene Formation, Dunkard Group, Lower Permian; Clark Hill section, Long Ridge, Monroe County, Ohio, USA) 10 (31206070732).jpg Sandstone (Greene Formation, Dunkard Group, Lower Permian; Monroe County, Ohio) | |
| Type | Group |
| Sub-units | Greene Formation, Washington Formation, Waynesburg Formation[1] |
| Underlies | Igneous intrusives |
| Overlies | Monongahela Formation |
| Lithology | |
| Primary | Shale, sandstone, siltstone, coal |
| Other | Limestone |
| Location | |
| Region | Ohio, Pennsylvania, West Virginia, and Maryland |
| Country | United States |
| Type section | |
| Named for | Dunkard Creek |
| Named by | I.C. White in 1891 |
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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.
Description
[edit | edit source]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 | edit source]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 | edit source]
References
[edit | edit source]Further reading
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- Geologic groups of Ohio
- Geologic groups of Pennsylvania
- Geologic groups of West Virginia
- Carboniferous System of North America
- Permian System of North America
- Permian United States
- Permian Ohio
- Permian geology of Pennsylvania
- Permian West Virginia
- Sandstone groups of the United States
- Shale groups of the United States
- Coal groups
- Limestone groups of the United States
- Siltstone groups