Geologic units in Morgan county, West Virginia

Additional scientific data in this geographic area

Chemung Group (Devonian) at surface, covers 32 % of this area

Gray to brown siltstone and sandstone with shale and conglomeratic interbeds; mainly marine and sparingly fossiliferous; boundaries gradational. Can be divided into the Voreknobs and Scherr Formations along the Allegheny Front. Parkhead Sandstone Member near base.

Hampshire Formation (Devonian) at surface, covers 24 % of this area

Non-marine shales and fine micaceous sandstones, mostly red to brownish-gray, including siltstone, sandstone and conglomerate. Generally distinguishable from the underlying Chemung by non-marine character and red color.

Pocono Group (Mississippian) at surface, covers 8 % of this area

Predominantly hard gray massive sandstones, with some shale. In the Eastern Panhandle, has been divided into the Hedges, Purslane, and Rockwell Formations.

Brallier Formation and Harrell Shale, undivided (Devonian) at surface, covers 7 % of this area

Brallier Formation : predominantly olive-gray to dark, thickly laminated marine shale, with considerable siltstone and thin sandstone lenses; mainly nonfossiliferous. Harrell Shale: dark gray to black thinly laminated to fissile shale. Calcareous shale and limestone lenses near the base (Tully).

McKenzie Formation and Clinton Group (Silurian) at surface, covers 7 % of this area

Includes the McKenzie Formation, consisting of shale with thin limestone lenses; the dark Rochester Shale; the white Keefer Sandstone; and the Rose Hill predominantly red shale, with thin sandstone interbeds, some of which are called "iron sandstones" from their reddish-brown color and hematite content.

Mahantango Formation (Devonian) at surface, covers 7 % of this area

(part of Millboro Shale) - thickly laminated marine shale, siltstone, very fine sandstone, and some limestone, with an occasional coral reef or biostrome. Contains the Clearville and Chaneysville Siltstone Members of Pennsylvania.

Tonoloway, Wills Creek, and Williamsport Formations (Silurian) at surface, covers 5 % of this area

Includes the thin-bedded platy argillaceous limestones of the Tonoloway, the thin-bedded shale with fossiliferous limestones of the Wills Creek, the Bloomsburg red clastic facies, and the greenish-brown to white Williamsport Sandstone. The Wills Creek contains anhydrite and rock salt, the latter supplying brine from deep wells along the Ohio River.

Tuscarora Sandstone (Silurian) at surface, covers 4 % of this area

Medium- to thick-bedded, white to gray or pinkish sandstone, fine to coarse, quartzitic, ridge-forming. Equivalent to the Clinch Sandstone of Tennessee.

Marcellus Formation and Needmore Shale, undivided (Devonian) at surface, covers 2 % of this area

Marcellus Formation (part of Millboro Shale): predominantly gray-black to black thinly laminated non-calcareous pyritic shale. Contains one or more thin-bedded limestones, including the Purcell Member of Pennsylvania. Needmore Shale (part of Onesquethaw ("Onondaga") Group): predominantly dark grey or green, calcitic, mostly non-fissile shale. Gives strong "kick" on gamma ray logs. Tioga Bentonite near the top. Includes the black Beaver Dam Shale Member. Grades westward into the Huntersville Chert. Not mappable at scale of this map. Included with Dmn.

Oriskany Sandstone and Helderberg Group, undivided (Devonian) at surface, covers 2 % of this area

Oriskany Sandstone: sometimes designated Ridgeley in eastern West Virginia. White to brown coarse- to fine-grained, partly calcareous sandstone, locally pebbly or conglomeratic, and ridge-forming. May be white, nearly pure silica, and a source of glass sand, as at Berkeley Springs, Morgan County. Helderburg Group: mostly cherty limestone, with some sandstone and shale. Contains several named stratigraphic units, including the Keyser Formation, which is partly Silurian and includes the Clifton Forge Sandstone and Big Mountain Shale Members.

Quaternary Alluvium (Quaternary) at surface, covers 0.7 % of this area

Alluvial deposits of sand, gravel, silt, and clay.

Juniata and Oswego Formations (Ordovician) at surface, covers 0.1 % of this area

The Juniata is a thin-bedded, blocky, red sandstone and shale. In places it is underlain by the thick-bedded, gray Oswego Sandstone.

"Chemung" Formation, Parkhead Sandstone, Brallier Formation, and Harrell Shale (Devonian) at surface, covers < 0.1 % of this area

"Chemung" Formation - Predominantly marine beds characterized by gray to olive-green graywacke, siltstone, and shale; thickened ranges from 2,000 to 3,000 feet; Parkhead Sandstone - Gray to olive-green sandy shale, conglomeratic sandstone and graywacke; present in Washington County, identification uncertain in west; thickness averages 400 feet; Brallier Fomation - (Woodmont Shale of earlier reports). Medium to dark gray, laminated shale and siltstone; weathers to light olive-gray; grain size coarsens upward; thickness about 2,000 feet in west, about 1,7000 feet in east; and Harrell Shale - Dark gray laminated shale; absent in east where Brallier lies directly on Mahantango, Tully Limestone lies near base in west, in subsurface of Garrett County; total thickness in west 140 to 300 feet.

Hampshire Formation (Devonian) at surface, covers < 0.1 % of this area

Interbedded red shale, red mudstone, and red to brown cross-bedded siltstone and sandstone; some thin green shale; greenish-gray sandstone and shale toward top; fragmentary plant fossils; thickness 1,400 to 2,000 feet in west, increases to 3,800 feet in east.

Wills Creek Shale and Bloomsburg Formation (Silurian) at surface, covers < 0.1 % of this area

Wills Creek Shale - Olive to yellowish-gray, thin-bedded mudstone, calcareous shale, argillaceous limestone, and sandstone; thickness 450 feet in west, increases to 600 feet in east; and Bloomsburg Formation - Bright red, hematitic, thin- to thick-bedded sandstone and shale; some dark sandstone and green shale; Cedar Creek Limestone Member - Dark gray, fine- to medium-grained argillaceous limestone, occurs in middle part of formation; total thickness 20 feet in west, increases to 200 feet in east.

McKenzie Formation (Silurian) at surface, covers < 0.1 % of this area

Gray, thin-bedded shale and argillaceous limestone; interbedded red sandstone and shale in east; thickness 160 feet in western Washington County, increases to 300 feet in east and 380 feet in west.

Clinton Group, including Rochester Shale (Silurian) at surface, covers < 0.1 % of this area

Gray, thin-bedded calcareous shale and dark gray, thin- to medium-bed7 ded lenticular limestone; thickness 25 to 40 feet; Keefer Sandstone - White to yellowish-gray, thick-bedded protoquartzite and orthoquartzite; calcareous to west; thickness 10 feet in west, increases to 35 feet in east; and Rose Hill Formation - Olive-gray to drab, thin-bedded shale; some purple shale and gray, thin-bedded sandstone; including Cresaptown Iron Sandstone Member - Purple, hematite-cemented, quartzose sandstone; thickness 5 to 30 feet; occurs in lower half of formation; total thickness 300 feet in east, increases to 570 feet in west.

Hamilton Group (including Mahantango Formation and Marcellus Shale), and including Tioga Metabentontite Bed, and Needmore Shale (Devonian) at surface, covers < 0.1 % of this area

Hamilton Group including Mahantango Formation - Dark gray, laminated shale, siltstone, and very fine-grained sandstone; thickness 600 feet in west, increases to 1,200 feet in east, and Marcellus Shale - Gray-black, thinly laminated, pyritic, carbonaceous shale; thickness 250 feet in east, increases to 500 feet in west. Also includes Tioga Metabentonite Bed - Brownish-gray, thinly laminated shale containing sand-size mica flakes; thickness less than one foot; and Needmore Shale - Olive-gray to black shale and dark, thin-bedded, fossiliferous, argillaceous limestone; thickness ranges from 70 to 145 feet.

Tonoloway Limestone (Silurian) at surface, covers < 0.1 % of this area

Gray, thin-bedded limestone, dolomitic limestone, and calcareous shale; thin sandstone member in east 20 feet above base; fossiliferous; thickness 400 feet in east, increases to 600 feet in west.

Oriskany Group including Ridgeley Sandstone and Shriver Chert (Devonian) at surface, covers < 0.1 % of this area

Oriskany Group, including Ridgeley Sandstone - White, medium- to coarse-grained, fossiliferous, calcareous orthoquartzite; thickness 160 feet in west. Medium to dark gray cherty, arenaceous limestone in east; thickness 50 feet; and Shriver Chert - Dark gray, brown, and black silty shales, cherty shales, and nodular and bedded black chert; fossiliferous; thickness 170 feet in west, upper boundary gradational with Ridgeley. Thickness 14 feet in east where the lower Shriver intertongues with the Licking Creek Limestone Member of the Helderberg Formation

Keefer, Rose Hill, and Tuscarora Formations (Silurian) at surface, covers < 0.1 % of this area

Keefer Sandstone (Ulrich, 1911). Sandstone, light-gray, fine-grained, cross-laminated, medium-bedded, very resistant. Thins northward and southwestward from a maximum of over 300 feet in Craig and western Botetourt counties. To the north it appears to interfinger with the Wills Creek and McKenzie Formations. The Keefer is equivalent to the upper portion of the Massanutten Sandstone. (The Keefer Sandstone, as used in this report, includes all of the quartzarenites with minor Skolithus-bearing red sand stone and minor calcite cemented quartzarenite in the interval above the Rose Hill Formation and below the Tonoloway Limestone in Botetourt, Rockbridge, and Augusta counties between Eagle Rock and Augusta Springs (Lampiris, 1976). Rose Hill Formation (Swartz, 1923). Sandstone, dark grayish-red, fine- to coarse-grained, poorly-sorted, argillaceous; hematite cemented, quartz sandstone interbedded with red or yellowish-green clay shale and greenish-gray, fine-grained sandstone. It is largely siltstone and shale with minor sandstone and thin limonitic iron ore beds in Southwest Virginia. Conformable with the underlying Tuscarora Formation, the Rose Hill Formation ranges up to 500 feet in thickness in northern and western Virginia but pinches-out in southwest ern Botetourt and Roanoke counties where the Keefer and Tuscarora For ma tions merge. It is present with other Silurian rocks everywhere except in the Massanutten Mountains or where an unconformity exists in exposures east of Walker Mountain. Tuscarora Formation (Darton and Taff, 1896). Quartzite, quartzarenite, and minor shale. Quartzite, light-gray with few nearly white, porcelaneous beds, fine- to medium-grained, with quartz-pebble conglomerate locally near base, quartz cemented, thick-bedded, and cross-bedded, resistant, cliff- and ledge-former, generally not more than 75 feet thick, comprises entire unit in many areas or is upper member where unconformably overlying a lower quartzarenite and shale member. Quartzarenite, light-yellowish-brown or medium-gray, fine-grained, thin-bedded, ranges in thickness from 0 to 175feet. Shale, light- to medium-brownish-gray, arenaceous, thin interbeds in quartzarenite. Conformably overlies the Juniata Formation in central western Virginia. Where lower member is absent the upper member unconformably overlies the Juniata, Oswego, Martinsburg, or Reedsville Formations or may be conformable with the Juniata Formation in northern Virginia. In southwestern Virginia grayish-red, fine-grained, ferruginous sandstone with lenses of coarse-grained, quartz sandstone and quartz-pebble conglomerate are included in the upper part of the formation. The Tuscarora is equivalent to the Clinch Formation and to the lower part of the Massanutten Sandstone.