The Allegheny Front is the major southeast- or east-facing

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. The terms ''scarp'' and ''scarp face'' are often used interchangeably with ''escar ...

in the

Allegheny Mountains The Allegheny Mountain Range (; also spelled Alleghany or Allegany), informally the Alleghenies, is part of the vast Appalachian Mountain Range of the Eastern United States and Canada and posed a significant barrier to land travel in less devel ...

in southern

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, ...

, western

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 to ...

, eastern

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 Bur ...

, and western

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 ar ...

, USA. The Allegheny Front forms the boundary between 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 ...

to its east and the

Appalachian Plateau The Appalachian Plateau is a series of rugged dissected plateaus located on the western side of the Appalachian Mountains. The Appalachian Mountains are a mountain range that run down the Eastern United States. The Appalachian Plateau is the nor ...

(locally called the

Allegheny Plateau The Allegheny Plateau , in the United States, is a large dissected plateau area of the Appalachian Mountains in western and central New York, northern and western Pennsylvania, northern and western West Virginia, and eastern Ohio. It is divide ...

) to its west. The Front is closely associated with the

Appalachian Mountains 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 ...

' Eastern Continental Divide, which in this area divides the waters of the

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

river system, flowing to the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

, from rivers flowing into

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the ...

and from there into the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

. The Allegheny Front and the Eastern Continental Divide do not always coincide; for example, the North Branch of the Potomac River begins well west of the Front, at the

Fairfax Stone Fairfax Stone Historical Monument State Park is a West Virginia state park commemorating the Fairfax Stone, a surveyor's marker and boundary stone at the source of the North Branch of the Potomac River. The original stone was placed on Octobe ...

near the southwestern tip of Maryland, about and across the actual divide from the headwaters of the

Youghiogheny River The Youghiogheny River , or the Yough (pronounced Yok ) for short, is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 tributary of the Monongahela River in the U.S. ...

draining northwards into the Monongahela and Ohio rivers. The Allegheny Front is one of the windiest spots east of the

, leading to the recent establishment of

wind farm A wind farm or wind park, also called a wind power station or wind power plant, is a group of wind turbines in the same location used Wind power, to produce electricity. Wind farms vary in size from a small number of turbines to several hundre ...

ing there. Allegheny Portage Railroad

Geography

The Allegheny Front forms part of the Appalachian Structural Front, separating the

from the Appalachians'

Ridge and Valley Province 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 ...

. The various other

s along this structural feature include the

Catskill Escarpment The Catskill Escarpment, often referred to locally as just the Escarpment or the Great Wall of Manitou, and known as the Catskill Front to geologists, is the range forming the northeastern corner of the Catskill Mountains in Greene and Ulster cou ...

to the northeast and the Cumberland Escarpment to the southwest. The Allegheny Front itself extends for about southwesterly from south-central

through

western Maryland upright=1.2, An enlargeable map of Maryland's 23 counties and one independent city Western Maryland, also known as the Maryland Panhandle, is the portion of the U.S. state of Maryland that typically consists of Washington, Allegany, and Garret ...

, then divides the

eastern panhandle of West Virginia The Eastern Panhandle is the eastern of the two panhandles in the U.S. state of West Virginia; the other is the Northern Panhandle. It is a small stretch of territory in the northeast of the state, bordering Maryland and Virginia. Some sources ...

from the rest of that state. The name "Allegheny Front" is applied to the escarpment throughout much of its extent, although it is little used in Maryland.

Elevations

The highest part of the crest of the Allegheny Front is also its southernmost high point, Mount Porte Crayon at , on the Pendleton/ Randolph county line in West Virginia. Its lowest point, , is along the North Branch of the Potomac River near

Keyser, West Virginia Keyser () is a city in and the county seat of Mineral County, West Virginia. It is part of the Cumberland, MD-WV Metropolitan Statistical Area. The population was 4,853 at the 2020 census. History Keyser, the county seat of Mineral County, is ...

. Other high points along the Front include the

Dolly Sods The Dolly Sods Wilderness – originally simply Dolly Sods – is a U.S. Wilderness Area in the Allegheny Mountains of eastern West Virginia, US, and is part of the Monongahela National Forest (MNF) of the U.S. Forest Service (USFS). Dolly Sods ...

area in West Virginia, a broad, rocky plateau at an elevation of about ; Dan's Rock on

Dans Mountain Dans Mountain is located in Allegany County, Maryland, USA between Georges Creek and the North Branch Potomac River. The highest point on Dans Mountain is called Dan's Rock which has an elevation of . The mountain rises above the town of LaVal ...

in Maryland at ; and

Blue Knob Blue Knob (elevation ) is a summit in the eastern United States with a broad dome that is the northernmost 3,000-footer in the Allegheny Mountains. It is the highest point in Bedford County, Pennsylvania. The mountain is the site of Blue Knob S ...

in northern Bedford County, Pennsylvania, with an elevation greater than .

Eastern Continental Divide

Local segments of the Eastern Continental Divide usually pass within a few miles of the Allegheny Front, and in many places coincide with it; this divide between waters of the

and the

separates the westward-flowing

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...

watershed from the eastward-flowing watersheds of the Susquehanna, Potomac, and

James James is a common English language surname and given name: *James (name), the typically masculine first name James * James (surname), various people with the last name James James or James City may also refer to: People * King James (disambiguati ...

rivers. A number of eastward-flowing creeks and rivers have their headwaters incised into Allegheny Front, displacing the Divide westward from the Front, including the North Branch of the Potomac River west of

Cumberland, Maryland Cumberland is a U.S. city in and the county seat of Allegany County, 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 s ...

, which originates well into the

at the

, just south of Maryland's southwestern tip. No waterway crosses the Front from east to west. 1827 Finley Map of Pennsylvania - Geographicus - Pennsylvania-finley-1827

1827 Finley Map of Pennsylvania - Geographicus - Pennsylvania-finley-1827

Course in detail

The Allegheny Front begins in central Pennsylvania just northwest of the town of

Lock Haven Lock Haven is the county seat of Clinton County, in the U.S. state of Pennsylvania. Located near the confluence of the West Branch Susquehanna River and Bald Eagle Creek, it is the principal city of the Lock Haven Micropolitan Statistical Area ...

and extends southwest paralleling, first,

Bald Eagle Mountain 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 al ...

, and then Brush Mountain to its east. The Front continues to a point a little north of the Pennsylvania/Maryland boundary where it is offset about to the east as it changes from the bold escarpment that characterized it west of Altoona to its more gentle rise in Maryland. Across the

Mason–Dixon line The Mason–Dixon line, also called the Mason and Dixon line or Mason's and Dixon's line, is a demarcation line separating four U.S. states, forming part of the borders of Pennsylvania, Maryland, Delaware, and West Virginia (part of Virginia ...

in Maryland, the Front becomes

, west of

Cumberland Cumberland ( ) is a historic county in the far North West England. It covers part of the Lake District as well as the north Pennines and Solway Firth coast. Cumberland had an administrative function from the 12th century until 1974. From 19 ...

, which reaches in elevation at Dan's Rock. Along Maryland's southern border, the North Branch of the Potomac River cuts down through the Front at just west of

. South of the Potomac, in West Virginia, the Front continues through the Mount Storm area, then passes along the eastern edge of

, a wide plateau of

Pottsville conglomerate 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 F ...

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

at about elevation. From the Sods, the front continues southward as an increasingly steep escarpment west of the North Fork of the South Branch of the Potomac River, with the Roaring Plains continuing the high plateaus of the Dolly Sods area along the escarpment's crest. The Allegheny Front's southern end is Mount Porte Crayon (), after which the land drops steeply to Seneca Creek, west of

Seneca Rocks Seneca Rocks is a large crag and local landmark in Pendleton County in the Eastern Panhandle of West Virginia, United States. The south peak is one of a small number of peaks inaccessible except by technical rock climbing techniques on the East ...

Escarpments southward

South of Mount Porte Crayon and Seneca Creek, the Appalachian Structural Front is less clearly unified. Pottsville-capped Spruce Mountain, south and east of Seneca Creek, continues the Allegheny Front's geology southward; this ridge reaches an elevation of at

Spruce Knob Spruce Mountain, located in eastern West Virginia, is the highest ridge of the Allegheny Mountains. The whale-backed ridge extends for only from northeast to southwest, but several of its peaks exceed in elevation. The summit, Spruce Knob (4863 ...

, West Virginia's highest point. Similarly steep escarpments sharing much of the same geologic structure are also present nearby along the eastern slopes of Allegheny Mountain and

Back Allegheny Mountain Back Allegheny Mountain is a long mountain ridge in eastern West Virginia. It is part of the Shavers Fork Mountain Complex in the Allegheny Mountains, Allegheny Range of the Appalachians. Geography Back Allegheny Mountain runs north to south a ...

(along with the southern end of

Shavers Mountain Shavers Mountain, is a high and rugged ridge situated in the Allegheny Mountains of eastern West Virginia. It is about long, north to south, and several of its peaks exceed in elevation. Shavers Mountain is notable for being "bookended", at its ...

), but these mountains lack the Pottsville caps characteristic of the Allegheny Front. Allegheny Mountain's long, nearly level crest is generally about in elevation, with Paddy Knob reaching . High points on Back Allegheny Mountain and adjacent Shavers Mountain include

Gaudineer Knob Gaudineer Knob is a mountain summit on the Randolph/ Pocahontas County line in eastern West Virginia, USA. It is the highest elevation (4,449 ft/1,356 m) of Shavers Mountain, a ridge of the Alleghenies, and is located about east of Cheat ...

() and

Bald Knob Bald Knob is the highest summit of Back Allegheny Mountain in Pocahontas County, West Virginia and is part of Cass Scenic Railroad State Park. At an altitude of above sea level, Bald Knob is the third-highest point in West Virginia and the Alle ...

(); these two mountains form a part of the divide between the

Monongahela River The Monongahela River ( , )—often referred to locally as the Mon ()—is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August 15, 2011 river on the Allegheny Plateau in North Cen ...

and New River portions of the Ohio River watershed.

Geology

Most of the Allegheny Front is capped by a nearly horizontal, erosion-resistant stratum (rock layer) of white

, sometimes where flat with younger

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

strata on top. The

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

-cemented

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

-containing Pottsville rock formed as part of a vast delta in the Pennsylvanian geologic period. The region was then uplifted and folded during the

Alleghenian Orogeny The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 195 ...

about 320-250 million years ago, during the

and

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

geological periods, forming the modern

as the ancient continents of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

collided due to plate tectonics processes. Subsequent

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

(for more than 200,000,000 years) has preferentially removed various softer surrounding rocks, especially the easily dissolved

Greenbrier limestone The Greenbrier Limestone, also known locally as the "Big Lime", is an extensive limestone unit deposited during the Middle Mississippian Epoch (345.3 ± 2.1 – 326.4 ± 1.6 Ma), part of the Carboniferous Period. This rock stratum is present be ...

, leaving areas of the hard Pottsville conglomerate as a caprock protecting softer rock strata immediately beneath. The Pottsville

outcrops conspicuously in various more exposed areas along the Front's eastern edge. Many of these clifftops offer broad scenic views, unlike most mountaintops within the generally forested Appalachians, and the more readily accessible are popular tourist destinations, including Dan's Rock on Dans Mountain in Maryland and the

and an overlook along

U.S. Route 50 in West Virginia U.S. Route 50 (US 50) in West Virginia runs from the border with Ohio to Virginia, passing briefly through Garrett County, Maryland, and following the Northwestern Turnpike. Prior to the U.S. Highway System it was West Virginia Route 1 and in th ...

. Since the eastern side of the Front is drained by

rivers that drop fairly rapidly through the

to the low-elevation waters of the

Great Appalachian Valley The Great Appalachian Valley, also called The Great Valley or Great Valley Region, is one of the major landform features of eastern North America. It is a gigantic trough—a chain of valley lowlands—and the central feature of the Appalachian M ...

, erosion on the eastern slope of this caprock layer has been much more intense than on the western slope, where drainage to low elevations is spread over a greater distance (particularly considering stream meanders) through the Appalachian Plateau to the Ohio River. These contrasting patterns of erosion produce a steep escarpment along much of the Front's eastern edge, with the mountains west of the Front generally grading more gently into the Appalachian Plateau.

Ecology

The nearly continuous high elevation and clifftop bedrock exposures of the Allegheny Front provide an important corridor of upland habitat in the central Appalachian Mountains.

Migratory bird flyway

During the fall, the Allegheny Front is associated with an important

flyway A flyway is a flight path used by large numbers of birds while migrating between their breeding grounds and their overwintering quarters. Flyways generally span continents and often pass over oceans. Although applying to any species of migrat ...

for migratory birds traveling from their northern breeding grounds to their southern wintering sites. In good weather, the birds can be seen from late morning, when they take advantage of the

thermals A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

— rising pockets of warm air — to facilitate flying, until the thermals cease in late afternoon. Among the bird-banding stations and migratory bird observatories associated with this flyway are: *Allegheny Front Hawk Watch on the border between

Bedford Bedford is a market town in Bedfordshire, England. At the 2011 Census, the population of the Bedford built-up area (including Biddenham and Kempston) was 106,940, making it the second-largest settlement in Bedfordshire, behind Luton, whilst ...

and

Somerset ( en, All The People of Somerset) , locator_map = , coordinates = , region = South West England , established_date = Ancient , established_by = , preceded_by = , origin = , lord_lieutenant_office =Lord Lieutenant of Somerset , lord_ ...

counties, Pennsylvania. On 20 September 2003, after the remnants of

Hurricane Isabel Hurricane Isabel was the strongest Atlantic hurricane since Mitch, and the deadliest, costliest, and most intense hurricane in the 2003 Atlantic hurricane season. Hurricane Isabel was also the strongest hurricane in the open waters of the Atlan ...

passed western Pennsylvania, 833 hawks were counted passing the site. The Allegheny Front Hawk Watch set three Eastern Flyway Golden Eagle records during the 2015 migration. The first was counting 74 Golden Eagle on October 24, 2015. This helped propel the hawk site to a new fall record of 320 Golden Eagles being counted during the fall migration. This coupled with the 66 goldens counted in the spring of 2015, yielded a total of 386 migrating birds for the year. *Allegheny Front Migratory Observatory (Bird Banding Station) near the Red Creek Campground at

, West Virginia. The station is open from August to October in good weather. Established in 1958, it is the only cooperative banding station in West Virginia.

The Dolly Sods area

In the

area of West Virginia, and southward toward Mount Porte Crayon, the Front is topped for more than by a broad, nearly flat plateau with many wide areas of exposed bedrock along the edge of the escarpment's drop to the North Fork River to the east, along the Front's base. Many of these windswept cliff-edge outcrops are sparsely vegetated, with occasional one-sided (

flagged Flagging may refer to: *Running out of time on a chess clock *Flagging (tape) Flagging is a coloured non-adhesive tape used in marking objects. It is commonly made of PVC or vinyl, though wood fibre cellulose-based biodegradable flagging also ex ...

) red spruce (''Picea rubens'') trees, and open habitats dominated by various low-growing

Appalachia Appalachia () is a cultural region in the Eastern United States that stretches from the Southern Tier of New York State to northern Alabama and Georgia. While the Appalachian Mountains stretch from Belle Isle in Newfoundland and Labrador, Ca ...

n and boreal plant species.

Economic importance

The long, steep, nearly continuous, often windswept escarpment of the Allegheny Front has both positive and negative effects on society and culture in the central Appalachians region.

Challenge to transportation and communication

Few roads or railroads cross the Allegheny Front, limiting transportation and communication between the regions to its east and west. Establishing passage of the Front was key to the development of the U.S. railroad network during the second half of the 19th century, thereby connecting the

Midwest The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four Census Bureau Region, census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of ...

by rail with the

Atlantic seaboard The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The eastern seaboard contains the coa ...

. The

Pennsylvania Railroad The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...

built the

Horseshoe Curve A horseshoe curve is a class of climbing curve in a roadbed which reverses turn direction (inflection) twice on either side of a single tight curve that varies through an angle of about 180 degrees or more. Such curves are more commonly found ...

track section west of Altoona, so that freight trains could ascend and descend to or from the Allegheny Plateau to the west.

Recreation and tourism

Substantial portions of the Allegheny Front's crest and slopes are parts of a national forest (the Monongahela in West Virginia) or various state, local, or private wildlands parks or preserves. The few readily accessible scenic viewpoints atop the Allegheny Front are popular tourist destinations. The Skyline Overlook along

is readily accessible by a major road. The Front is also a significant part of scenic views from various highways and mountains to its east, such as

North Fork Mountain North Fork Mountain is a quartzite-capped mountain ridge in the Ridge and Valley physiographic province of the Allegheny Mountains (or "High Alleghenies" or "Potomac Highlands") of eastern West Virginia. Kile Knob, at 4,588 feet (1,398 m), is th ...

in West Virginia.

Wind farming

The NedPower Mount Storm Wind Project in West Virginia includes 132

wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...

s along of the Allegheny Front in

Grant County Grant County may refer to: Places ;Australia * County of Grant, Victoria ;United States *Grant County, Arkansas *Grant County, Indiana * Grant County, Kansas *Grant County, Kentucky *Grant County, Minnesota *Grant County, Nebraska *Grant C ...

near Mount Storm. Constructed between 2006 and 2008, it generates up to 264

megawatt The watt (symbol: W) is the unit of Power (physics), power or radiant flux in the International System of Units, International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantification (science), ...

s of electricity for the mid-Atlantic

power grid An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power ...

, enough to service about 66,000 homes and businesses. In December 2016, Save Our Allegheny Ridges, a group that opposes energy development on forested mountaintops, said in a news release that Invenergy plans to install a series of wind turbines atop Shaffer Mountain in Somerset County just a few miles north of the Allegheny Front Hawk Watch.

References

External links

NedPower Mount Storm webpage
{{Monongahela National Forest Escarpments of the United States Ridges of Maryland Ridges of Pennsylvania Ridges of West Virginia Allegheny Plateau Monongahela National Forest