Washington Formation

The Washington Formation is a coal, sandstone, and limestone geologic formation located in Ohio, Pennsylvania and West Virginia.^[1] It dates back to the Lower Permian period, with its base at or near the Permian/Carboniferous boundary.^{[2] [3]} The Washington formation and the Dunkard Group as a whole was deposited at a time when the continents were in the process of forming the "Super Continent" Pangaea as well as a gradual drop in sea levels.^[4] The result during this period was coals being thinner and impure with high ash content. The limestones found with in the formation are exclusively freshwater deposits.

Washington Formation
Stratigraphic range: Permian
Bituminous coal (Washington Coal, Upper Pennsylvanian; Ohio)
Type	Formation
Unit of	Dunkard Group[1]
Sub-units	Upper Washington Jollytown coal Hundred sandstone Upper Marietta Washington “A” coal Middle Washington Lower Washington Lower Marietta Washington (No. 12) coal Little Washington coal Mannington sandstone Waynesburg “A” coal Waynesburg Sandstone Elm Grove limestone Cassville
Underlies	Greene Formation
Overlies	Waynesburg Formation
Lithology
Primary	limestone, sandstone, coal
Other	shale
Location
Region	Ohio and  West Virginia
Country	United States

References

1. Berryhill, Henry L. Jr.; 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. Wayne Martin, Bernard Henniger (1965). "The Hockingport and Waynesburg Sandstones (Pennsylvanian and Permian) of the Dunkard Group: ABSTRACT". AAPG Bulletin. 49. doi:10.1306/a66335b4-16c0-11d7-8645000102c1865d. ISSN 0149-1423.
3. M. A. Rendina, Wayne D. Martin (1985). "Provenance of Selected Sandstones and Mud Rocks of Dunkard Group (Upper Pennsylvanian-Permian) in Ohio, West Virginia, and Pennsylvania: ABSTRACT". AAPG Bulletin. 69. doi:10.1306/94885417-1704-11d7-8645000102c1865d. ISSN 0149-1423.
4. Haq, Bilal U.; Schutter, Stephen R. (2008-10-03). "A Chronology of Paleozoic Sea-Level Changes". Science. 322 (5898): 64–68. doi:10.1126/science.1161648. ISSN 0036-8075.