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Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Named
  • Dominant lithology:
    • Sandstone
    • Siltstone
  • AAPG geologic province:
    • Appalachian basin
Publication:

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.


Summary:

Unit here named for the topographic feature called Fore Knobs of Allegheny Front and assigned as upper formation of the newly named Greenland Gap Group, which replaces Chemung Formation in the report area. Unit exposed in outcrops from Allegany Co., MD, to Highland Co., VA. Contains abundant massive sandstones; considerable siltstone; substantial "redbeds" of brownish-gray sandstone, siltstone, and shale containing scattered marine fossils; and occasional quartz-pebble conglomerate or conglomeratic sandstone beds. Unit formerly called upper sandy part of Chemung Formation. Lower Foreknobs probably correlates with Elkins Member of Chemung Formation (Reger, 1928, 1931) west of Allegheny Front in Randolph Co. Subdivided into (ascending) Mallow Member, Briery Gap Sandstone Member, Blizzard Member, Pound Sandstone Member, and an unnamed member. Underlies Hampshire Formation; disconformably overlies Scherr Formation (named). 1321 ft (403 m) thick at type section; ranges to 585 m. Age is Late Devonian. Formation boundary is probably time-transgressive, becoming younger to the southwest.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation*
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

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, 1 sheet, 6 p., scale 1:24,000


Summary:

Scherr and Foreknobs Formations of Dennison (1970) here geographically extended into south-central PA and adopted for use by the USGS in the report area and in their type locality state of WV. Greenland Gap Group not used in this report.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Appalachian basin
Publication:

McGhee, G.R., Jr., and Dennison, J.M., 1976, The Red Lick Member, a new subdivision of the Foreknobs Formation (Upper Devonian) in Virginia, West Virginia, and Maryland: Southeastern Geology, v. 18, no. 1, p. 49-57.


Summary:

Red Lick Member here named and assigned to Foreknobs Formation as uppermost unit, overlying Pound Sandstone Member. Southwest of Rte 250 in VA, Foreknobs is not divided into members.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation*
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

Perry, W.J., Jr., 1978, Sequential deformation in the central Appalachians: American Journal of Science, v. 278, no. 4, p. 518-542.


Summary:

Scherr and Foreknobs Formations extended into west-central VA for USGS use. Greenland Gap Group not used in this report.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

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.


Summary:

Foreknobs and Scherr Formations are not recognized in the subsurface of WV; therefore, Greenland Gap is reduced to formation rank west of the Allegheny Front where it replaces use of the term "Chemung." Uppermost members of the Foreknobs (Red Lick and Pound) are retained as members of the Greenland Gap Formation.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Revised
    • Overview
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

Warne, A.G., and McGhee, G.R., Jr., 1991, Stratigraphic subdivisions of the Upper Devonian Scherr, Foreknobs, and Lock Haven Formations near the Allegheny Front of central Pennsylvania: Northeastern Geology, v. 13, no. 2, p. 96-109.


Summary:

In south-central PA, the Minnehaha Springs Member of the Scherr Formation and the Mallow, Briery Gap, Blizzard, Pound, and Red Lick Members of the Foreknobs Formation of the Greenland Gap Group are recognized. The Foreknobs is composed of variegated sandstone, siltstone, and shale with local quartz-pebble conglomerate. Unit ranges from 1320 to 2260 ft thick and averages about 1800 ft.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

Dennison, J.M., Filer, J.K., and Rossbach, T.J., 1994, Upper Devonian outcrop stratigraphy along the Appalachian basin margin in southeastern West Virginia and southwestern Virginia and implications for hydrocarbon exploration, IN Schultz, A.P., and Rader, E.K., eds., Studies in eastern energy and the environment: Virginia Division of Mineral Resources Publication, no. 132, p. 43-49., See also 1994 AAPG Eastern Section Spec. Vol. (Williamsburg, VA, Sept. 19-21, 1993)


Summary:

The term Foreknobs Formation is not used in the stratigraphic cross section south of Gap Mills, WV. Arbitrary cutoffs are drawn where diagnostic characteristics are lost by facies change. The Mallow Member coarsens upward and also becomes finer grained toward the southwest. Cutoffs of the base of the Mallow Member are drawn between Alleghany and White Sulphur Springs. All sandstone in the Mallow, Briery Gap, Blizzard, and Pound Members is lost southwest of White Sulphur Springs resulting in an arbitrary cutoff of the base of the Foreknobs, which jumps up to the base of the Red Lick Member near Gap Mills. The Red Lick then loses all of its sandstone between Gap Mills and Bluefield.

Source: GNU records (USGS DDS-6; Reston GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Foreknobs Formation
  • Modifications:
    • Areal extent
  • AAPG geologic province:
    • Appalachian basin
Publication:

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.


Summary:

Foreknobs Formation used in the Catawba syncline of southwestern VA to encompass the lower part of those rocks previously mapped as Chemung by Amato (1974). All five members are present. Overlies Brallier Formation, as Scherr Formation is not recognized in this area. Underlies Hampshire Formation, which replaces usage of the upper Chemung in this area.

Source: GNU records (USGS DDS-6; Reston GNULEX).


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Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

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