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.

References

  1. ^ a b 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.


Allikas: http://en.wikipedia.org/wiki/Washington_Formation
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