Reedsville Formation | |
---|---|
Stratigraphic range: Late Ordovician | |
Type | sedimentary |
Unit of | Chickamauga Group (TN only) [1] |
Underlies | Bald Eagle Formation and Juniata Formation |
Overlies | Antes Gap Shale, Trenton Limestone in TN and Utica Shale in WV |
Lithology | |
Primary | shale |
Other | sandstone |
Location | |
Region | Appalachian Mountains |
Extent | Maryland, Pennsylvania, Tennessee, Virginia, [2] West Virginia |
Type section | |
Named for | Reedsville, Pennsylvania |
Named by | E. O. Ulrich [3] |
The Ordovician Reedsville Formation is a mapped surficial bedrock unit in Pennsylvania, Maryland, Virginia, West Virginia, and Tennessee, that extends into the subsurface of Ohio. This rock is a slope-former adjacent to (and stratigraphically below) the prominent ridge-forming Bald Eagle sandstone unit in the Appalachian Mountains. It is often abbreviated Or on geologic maps.
The Reedsville Formation is an olive-gray to dark-gray siltstone, shale, and fine-grained sandstone. [4] In Central Pennsylvania along the Nittany Arch, and extending into the subsurface of northern West Virginia, the base of the Reedsville formation includes the black calcareous Antes Shale formation. [5]
The type locality is at Reedsville, Pennsylvania.
Relative age dating of the Reedsville places it in the Upper Ordovician. It rests conformably atop the Upper Ordovician Coburn Formation at the top of the Trenton Group limestone and conformably below the Bald Eagle Formation. [6]
Isotopic dating of shale mylonite in Pennsylvania reveals a K-Ar age of 372+/-8 Ma. [7]
The Reedsville is quarried locally in borrow pits for road material and fill. [8]
Taxa | Class | Description | Images |
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Cephalopod | |||
Bald Eagle Mountain – once known locally as Muncy Mountain – is a stratigraphic ridge in the Ridge-and-Valley Appalachians of central Pennsylvania, United States, running east of the Allegheny Front and northwest of Mount Nittany. It lies along the southeast side of Bald Eagle Creek and south of the West Branch Susquehanna River, and is the westernmost ridge in its section of the Ridge-and-Valley Appalachians. The ridge line separates the West Branch Susquehanna Valley from the Nippenose and White Deer Hole valleys, and Bald Eagle Valley from Nittany Valley.
Brush Mountain is a stratigraphic ridge in the Appalachian Mountains of central Pennsylvania, United States, lying east of the Allegheny Front and west of Tussey Mountain. It runs along the southeast side of the Little Juniata River and forms a horseshoe around Sinking Run, and is the westernmost ridge in its section of the Ridge-and-valley Appalachians. The western ridge line separates the Logan Valley from the Sinking Valley.
The Silurian Bloomsburg Formation is a mapped bedrock unit in Pennsylvania, New Jersey, New York and Maryland. It is named for the town of Bloomsburg, Pennsylvania in which it was first described. The Bloomsburg marked the first occurrence of red sedimentary rocks in the Appalachian Basin.
The Ordovician Martinsburg Formation (Om) is a mapped bedrock unit in Pennsylvania, New Jersey, Maryland, Virginia, and West Virginia. It is named for the town of Martinsburg, West Virginia for which it was first described. It is the dominant rock formation of the Great Appalachian Valley in New Jersey (where it is called Kittatinny Valley and Pennsylvania.
The Silurian Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia, USA.
The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.
The Ordovician Bald Eagle Formation is a mapped bedrock unit in central Pennsylvania, USA. It is a ridge-forming unit in the Appalachian Mountains.
Jacks Mountain is a stratigraphic ridge in central Pennsylvania, United States, trending southeast of the Stone Mountain ridge and Jacks Mountain Anticline. The ridge line separates Kishacoquillas Valley from the Ferguson and Dry Valleys. Jacks Mountain lies in Mifflin, Huntingdon, Snyder, and Union Counties, and the ridge line forms part of the border between Huntingdon and Mifflin Counties.
The Clinton Group is a mapped unit of sedimentary rock found throughout eastern North America. The interval was first defined by the geologist Lardner Vanuxem, who derived the name from the village of Clinton in Oneida County, New York where several well exposed outcrops of these strata can be found. The Clinton Group and its lateral equivalents extend throughout much of the Appalachian Foreland Basin, a major structural and depositional province extending from New York to Alabama. The term has been employed in Kentucky, Maryland, Michigan, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia, though in many of these areas the same interval is referred to as the Rose Hill, Rockwood, or Red Mountain Formations. Historically the term "Clinton" has also been assigned to several lower Silurian stratigraphic units in Ohio and Kentucky which are now known to be significantly older than the Clinton Group as it was originally defined. Many parts of this succession are richly fossiliferous, making the Clinton Group an important record of marine life during the early Silurian. Several economically valuable rock-types are found within this interval, though it is perhaps best known as a significant source of iron ore
Wills Creek Formation is a mapped Silurian bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
The Hamilton Group is a Devonian-age geological group in the Appalachian region of the United States. It is present in New York, Pennsylvania, Maryland, Ohio, West Virginia, northwestern Virginia and Ontario, Canada. It is mainly composed of marine shale with some sandstone. There are two main formations encompassed by the group: the Mahantango Formation and the Marcellus Shale. In southwestern Virginia, where the two sub-units are not easily distinguishable, the Hamilton Group is broadly equivalent to the Millboro Shale or Millboro Formation. The group is named for the village of Hamilton, New York. These rocks are the oldest strata of the Devonian gas shale sequence.
The Devonian Mahantango Formation is a mapped bedrock unit in Pennsylvania, West Virginia, and Maryland. It is named for the North branch of the Mahantango Creek in Perry and Juniata counties in Pennsylvania. It is a member of the Hamilton Group, along with the underlying the Marcellus Formation Shale. South of Tuscarora Mountain in south central Pennsylvania, the lower members of this unit were also mapped as the Montebello Formation. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database.
The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, Ohio, and Alabama. It is a major ridge-former in the Ridge-and-Valley Appalachians of the eastern United States. The Pottsville Formation is conspicuous at many sites along the Allegheny Front, the eastern escarpment of the Allegheny or Appalachian Plateau.
The Marcellus Formation or the Marcellus Shale is a Middle Devonian age unit of sedimentary rock found in eastern North America. Named for a distinctive outcrop near the village of Marcellus, New York, in the United States, it extends throughout much of the Appalachian Basin.
The Devonian Old Port Formation is a mapped bedrock unit in Pennsylvania, USA. Details of the type section and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. Current nomenclature usage by U.S. Geological Survey restricts the name Old Port Formation to Pennsylvania, but correlative units are present in adjacent states.
The Late Silurian Tonoloway Formation is a mapped limestone bedrock unit in Pennsylvania, Maryland, Virginia and West Virginia.
The Devonian Scherr Formation is a mapped bedrock unit in Pennsylvania, Maryland, Virginia and West Virginia.
The Devonian Foreknobs Formation is a mapped bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
Canoe Mountain is a stratigraphic ridge in central Pennsylvania, United States, running east of the Allegheny Front and west of Tussey Mountain. It forms a continuous ridge with Brush Mountain to the west. To the south, across the water gap formed by the Frankstown Branch Juniata River, the ridgeline continues as Lock Mountain.
The Mansfield Natural Gas Field is located west of Mansfield, Ohio, within the Appalachian foreland basin. The field is 1.5 miles long by 1.4 miles wide and is in a general oval shape, stretching northward. This field, although small, is an analog for many of the natural gas fields that occur within the Appalachian Basin. It was first discovered by the Pan American Petroleum and Transport Company in the early 1930s. It is part of the Utica – Lower Paleozoic system, which is estimated to make up 15 to 20 percent of the total hydrocarbon abundance of the Appalachian Basin.