imported>Volcanoguy: removed Category:Conglomerate formations; added Category:Conglomerate formations of the United States using HotCat

2025-06-20T19:04:58Z

removed Category:Conglomerate formations; added Category:Conglomerate formations of the United States using HotCat

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{{Short description|Geological formation in the United States}}
{{Infobox rockunit
| name = Foreknobs Formation
| image = Conglomerate_Foreknobs_Fm.jpg
| caption = [[Conglomerate (geology)|Conglomerate]] from Foreknobs Formation, Rt. 994, near western side of bridge going over [[Raystown Lake]], [[Huntingdon County, Pennsylvania]]
| type = sedimentary
| age = [[Frasnian]] - [[Famennian]]<ref>[http://hdl.handle.net/10919/19078 Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau]</ref>
| period = Late Devonian
| prilithology = [[Siltstone]], [[sandstone]], [[shale]]
| otherlithology = [[Conglomerate (geology)|Conglomerate]]
| namedfor = Fore Knobs of [[Allegheny Front]]
| namedby = J. M. Dennison, 1970
| region = [[Appalachian Mountains]]
| country =
| coordinates =
| unitof = Greenland Gap Group
| subunits = Mallow Member, Briery Gap Sandstone Member, Blizzard Member, Pound Sandstone Member, and Red Lick Member
| underlies = [[Catskill Formation]], or [[Hampshire Formation]] in VA
| overlies = [[Scherr Formation]], or [[Brallier Formation]] in VA
| thickness = 1321 ft at type section
| extent = [[Pennsylvania]], [[Maryland]], [[Virginia]], [[West Virginia]]
| area =
| map =
| map_caption =
}}
The [[Devonian]] '''Foreknobs Formation''' is a mapped [[bedrock]] unit in [[Pennsylvania]], [[Maryland]], [[Virginia]], and [[West Virginia]].

==Description==
The Foreknobs Formation contains massive [[sandstone]]s; [[siltstone]]; "redbeds" of brownish-gray sandstone, siltstone, and [[shale]] containing scattered marine fossils; and occasional quartz-pebble [[conglomerate (geology)|conglomerate]] or conglomeratic sandstone beds.<ref>Dennison, J.M., 1970, Stratigraphic divisions of Upper Devonian Greenland Gap Group ("Chemung Formation") along Allegheny Front in West Virginia, Maryland, and Highland County, Virginia: Southeastern Geology, v. 12, no. 1, p. 53-82.</ref>

===Stratigraphy===
Dennison (1970) renamed the old Chemung Formation the Greenland Gap Group and divided it into the lower [[Scherr Formation]] and the upper Foreknobs Formation. De Witt (1974) extended the Scherr and Foreknobs into Pennsylvania, but did not use the term Greenland Gap Group.<ref>de Witt, Wallace, Jr., 1974, Geologic map of the Beans Cove and Hyndman quadrangles and part of the Fairhope quadrangle, Bedford County, Pennsylvania: U.S. Geological Survey Miscellaneous Investigations Series Map, I-801, 6 p., 1 sheet, scale 1:24,000</ref>

Boswell, et al. (1987), does not recognize the Scherr and Foreknobs Formations in the subsurface of West Virginia and thus these formations are reduced from "group" to "formation" as the Greenland Gap Formation.<ref>Boswell, R.M., Donaldson, A.C., and Lewis, J.S., 1987, Subsurface stratigraphy of the Upper Devonian and Lower Mississippian of northern West Virginia: Southeastern Geology, v. 28, no. 2, p. 105-131.</ref>

Rossbach and Dennison (1994) extended the Foreknobs into the Catawba syncline of southwestern Virginia.<ref>Rossbach, T.J., and Dennison, J.M., 1994, Devonian strata of Catawba syncline, near Salem, Virginia, IN Schultz, Art, and Henika, Bill, Fieldguides to Southern Appalachian structure, stratigraphy, and engineering geology: Virginia Polytechnic Institute and State University, Department of Geological Sciences Guidebook, Geological Society of America, Southeastern Section, Annual Meeting, Blacksburg, VA, April 7–9, 1994, no. 10, p. 95-126.</ref>

The Foreknobs is divided into the following Members, in ascending order: Mallow Member, Briery Gap Sandstone Member, Blizzard Member, Pound Sandstone Member, and Red Lick Member

===Fossils===
[[Image:Foreknobs brachiopods.jpg|thumb|left|Foreknobs Formation containing abundant ''[[Mucrospirifer]]'' brachiopods, from near upper reservoir of [[Bath County Pumped Storage Station]]]]
Red beds within the Foreknobs contain scattered marine fossils, such as [[brachiopod]]s.

===Notable Exposures===
Type section: along WV Highway 42, 0.48 km northwest of [[Scherr, West Virginia|Scherr]], [[Grant County, West Virginia]]

== Age ==
Relative age dating places the Foreknobs in the [[Devonian|Late Devonian]].

== References ==
{{reflist}}

{{Chronostratigraphy of Maryland}}
{{Chronostratigraphy of Virginia}}
{{Stratigraphic column of West Virginia}}

[[Category:Sandstone formations of the United States]]
[[Category:Shale formations of the United States]]
[[Category:Siltstone formations of the United States]]
[[Category:Devonian Maryland]]
[[Category:Devonian geology of Pennsylvania]]
[[Category:Devonian geology of Virginia]]
[[Category:Devonian West Virginia]]
[[Category:Geologic formations of Maryland]]
[[Category:Geologic formations of Pennsylvania]]
[[Category:Geologic formations of Virginia]]
[[Category:Geologic formations of West Virginia]]
[[Category:Devonian southern paleotemperate deposits]]
[[Category:Conglomerate formations of the United States]]

{{Maryland-geologic-formation-stub}}

Foreknobs Formation - Revision history

imported>Volcanoguy: removed Category:Conglomerate formations; added Category:Conglomerate formations of the United States using HotCat