The

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleoz ...

Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...

unit in

Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean t ...

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...

, and

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...

, USA.

Description

The Tuscarora is a thin- to thick-bedded fine-grained to coarse-grained

orthoquartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...

. It is a white to medium-gray or gray-green subgraywacke,

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, ...

and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...

, cross-stratified and conglomeratic

conglomerate Conglomerate or conglomeration may refer to: * Conglomerate (company) * Conglomerate (geology) * Conglomerate (mathematics) In popular culture: * The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes ** ...

in parts, containing a few

interbeds.Berg, T.M., Edmunds, W.E., Geyer, A.R. and others, compilers, (1980). Geologic Map of Pennsylvania: Pennsylvania Geologic Survey, Map 1, scale 1:250,000. Details of the type locality 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 Tuscarora and its lateral equivalents are the primary ridge-formers of the

Ridge-and-Valley Appalachians The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

in the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

It is typically 935 feet thick in Pennsylvania, and in Maryland varies from 60 feet to 400 feet thick from east to west.

Notable exposures

The Tuscarora Formation is commonly exposed on various ridge crests and in many

water gap A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a prac ...

s in the

Ridge and Valley The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian division and are also a belt within the Appalachian Mountains extending ...

physiographic province of the

Appalachians The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

of Pennsylvania, Maryland, and West Virginia, particularly along the Wills Mountain Anticline. In Pennsylvania, the Tuscarora is exposed along

US 30 U.S. Route 30 or U.S. Highway 30 (US 30) is an east–west main route in the system of the United States Numbered Highways, with the highway traveling across the northern tier of the country. With a length of , it is the third longest ...

on the north and south sides of the

Narrows A narrows or narrow (used interchangeably but usually in the plural form), is a restricted land or water passage. Most commonly a narrows is a strait, though it can also be a water gap. A narrows may form where a stream passes through a tilted ...

in central Bedford County, where it is nearly vertical. It is also well-exposed in the core of Jack's Mountain in Jack's Narrows, where the

Juniata River The Juniata River () is a tributary of the Susquehanna River, approximately long,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map , accessed August 8, 2011 in central Pennsylvania. The river is c ...

cuts through the mountain, just west of Mount Union. The

Standing Stone Trail The Standing Stone Trail is an linear hiking trail in south-central Pennsylvania, leading from Cowans Gap State Park in Fulton County, north to Detweiler Run Natural Area in Huntingdon County. Most of the trail follows rocky ridgetops in the ...

traverses this cut, and many of the "Thousand Steps" here are Tuscarora quartzite. In Maryland, the

National Road The National Road (also known as the Cumberland Road) was the first major improved highway in the United States built by the federal government. Built between 1811 and 1837, the road connected the Potomac and Ohio Rivers and was a main tran ...

(

US 40 U.S. Route 40 or U.S. Highway 40 (US 40), also known as the Main Street of America, is a major east–west United States Highway traveling across the United States from the Mountain States to the Mid-Atlantic States. As with most routes ...

) passes arched Tuscarora sandstone outcrops in the

Cumberland Narrows The Cumberland Narrows (or simply The Narrows) is a water gap in western Maryland in the United States, just west of Cumberland. Wills Creek cuts through the central ridge of the Wills Mountain Anticline at a low elevation here between Wills Mo ...

in Allegany County. In West Virginia, the River Knobs along the North Fork of the South Branch of the Potomac River in Pendleton County include dramatic outcrops of nearly vertical Tuscarora sandstone. Some of the better known of these exposures are Seneca Rocks, Champe Rocks, Judy Rocks, and Nelson Rocks. These cliffs are clearly visible along U.S. Route 33 and West Virginia Routes 28 and 55. North Fork Mountain, to the east of the River Knobs, is a long

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is t ...

ridge capped by Tuscarora sandstone. Two of the more comprehensive exposures of the Tuscarora Formation are in two quarries at the crest and south end of

Canoe Mountain 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 fo ...

Spruce Creek Quadrangle
.

Geographic Extent

The Tuscarora is present in

, and

, USA.

Stratigraphic Setting

The Tuscarora rests conformably atop the

Juniata Formation 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 t ...

and conformably below the

Clinton Group The Clinton Group (also referred to as the Clinton Formation or the Clinton Shale) 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 ...

. The Tuscarora is a lateral equivalent of the Minsi and Weiders members of the Shawangunk Formation in eastern

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delawa ...

, and

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

, and of the Massanutten Formation in

, and the Clinch Sandstone farther south. Butts (1940) indicated that in the Appalachian Valley and Ridge Province the name "Tuscarora Sandstone" should be applied to these strata from Pennsylvania in the north to 38deg N latitude, and that the name "Clinch Sandstone" should be applied to these strata south of 38deg N latitude. There is one named

member Member may refer to: * Military jury, referred to as "Members" in military jargon * Element (mathematics), an object that belongs to a mathematical set * In object-oriented programming, a member of a class ** Field (computer science), entries in ...

of the formation: Castanea, occurring at the top, leaving the Lower and Middle Tuscarora Formation at the bottom. This formation has been called the "White Medina Sandstone" in West Virginia.

Fossils

Very few fossils exist in the Tuscarora, and most of them are

trace fossils A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils ...

. At least two hughmilleriid Eurypterids (sea scorpions) have been discovered in the Tuscarora.Boucot, A.J., Gray, Jane, and Hoskins, D.M., 1994, New hughmilleriid (Eurypterida) occurrence from the Tuscarora Formation, central Pennsylvania, and its environmental interpretation, IN Landing, Ed, ed., Studies in stratigraphy and paleontology in honor of Donald W. Fisher: New York State Museum Bulletin, no. 481, p. 21-23.

Age

Relative age dating of the Tuscarora places it in the Lower

period, being deposited between 440 and 417 (±10) million years ago.

Interpretations of Depositional Environment

The

depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical, and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be ...

of the Tuscarora has always been interpreted as mostly terrestrial or shallow marine deposits resulting in a molasse sequence produced by the

Taconic orogeny The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the Unit ...

. It is thought to represent a vast sand shoal along the margin of the

Iapetus Ocean The Iapetus Ocean (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleo ...

. Ripple marks are seldom found, but do support interpretation as a shallow marine depositional environment.

Economic uses

The Tuscarora may have been used as a

ganister A ganister (or sometimes gannister ) is hard, fine-grained quartzose sandstone, or orthoquartzite,Jackson, J. A., 1997, ''Glossary of geology'', 4th ed. American Geological Institute, Alexandria. used in the manufacture of silica brick typically ...

for making furnace liners in 19th century

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a c ...

blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being "forced" or supplied above atmospheri ...

s of central Pennsylvania. The Tuscarora has become very important to the tourism industry of eastern West Virginia, where the formation has many conspicuous outcrops visible from such roads as U.S. Routes 33 and 50 and West Virginia Routes 28 and 55. Tuscarora-capped North Fork Mountain and various Tuscarora cliffs are prominent in scenic views from such sites as Spruce Knob and Dolly Sods. Seneca Rocks in Pendleton County, West Virginia, has become a world-renowned

rock climbing Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the summit of a formation or the endpoint of a usually pre-defined route without falling. Rock climbing is a physically a ...

location. It is the only "true peak" (a peak inaccessible except by technical

techniques) on the East Coast of the United States. Two climbing schools near the outcrop and many other guide services offer guided climbing trips on the 300+ climbing routes on the west-facing cliff. Seneca Rocks is managed by the

U.S. Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency inc ...

, and is located within the Spruce Knob–Seneca Rocks National Recreation Area of the Monongahela National Forest. The Nelson Rocks Preserve, located near Circleville, West Virginia, is a privately owned and operated nature preserve dedicated to preserving Nelson Rocks and the surrounding environment as a cultural, educational, and recreational resource. The preserve offers a

via ferrata A via ferrata ( Italian for "iron path", plural ''vie ferrate'' or in English ''via ferratas'') is a protected climbing route found in the Alps and certain other locations. The term "via ferrata" is used in most countries and languages except ...

climbing trail, one of six in the United States.

References

{{Stratigraphic column of West Virginia Silurian System of North America Quartzite formations Sandstone formations of the United States Shale formations of the United States Siltstone formations Silurian United States Silurian Maryland Silurian geology of Pennsylvania Silurian geology of Virginia Silurian West Virginia Cliff-formers Aeronian Telychian

Description

Notable exposures

Geographic Extent

Stratigraphic Setting

Fossils

Age

Interpretations of Depositional Environment

Economic uses

See also

References