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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 ''esca ...
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, Ma ...
, western
Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), 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; ...
, 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 ...
, 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 East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...
, 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 extendin ...
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 no ...
(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 divided ...
) 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. The ...
' Eastern Continental Divide, which in this area divides the waters of the
Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...
/
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. Mis ...
river system, flowing to the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an 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 the United S ...
, 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#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
. 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 near the southwestern tip of Maryland, about and across the actual divide from the headwaters of the Youghiogheny River
draining Draining may refer to: * Drainage, the natural or artificial process of water removal from land * the urban exploration of sewers and storm drains See also * Drain (disambiguation) {{Disambiguation ...
northwards into the Monongahela and Ohio rivers. The Allegheny Front is one of the windiest spots east of the
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. Mis ...
, 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 to produce electricity. Wind farms vary in size from a small number of turbines to several hundred wind tur ...
ing there.


Geography

The Allegheny Front forms part of the Appalachian Structural Front, separating 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 no ...
from the Appalachians' Ridge and Valley Province. The various other
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 ''esca ...
s along this structural feature include the Catskill Escarpment to the northeast and the Cumberland Escarpment to the southwest. The Allegheny Front itself extends for about southwesterly from south-central
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, Ma ...
through western Maryland, then divides the eastern panhandle of West Virginia 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 Mount Porte Crayon is a mountain in the Roaring Plains Wilderness of the Monongahela National Forest in the northeastern corner of Randolph County, West Virginia, USA. It rises to an elevation of , the elevational climax of the Allegheny Front. T ...
at , on the
Pendleton Pendleton may refer to: Places ;United Kingdom *Pendleton, Lancashire, England *Pendleton, Greater Manchester, England ;United States *Pendleton, Indiana * Pendleton, Missouri *Pendleton, New York *Pendleton, Oregon *Pendleton, South Carolina *Pe ...
/
Randolph Randolph may refer to: Places In the United States * Randolph, Alabama, an unincorporated community * Randolph, Arizona, a populated place * Randolph, California, a village merged into the city of Brea * Randolph, Illinois, an unincorporated commun ...
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, i ...
. Other high points along the Front include the Dolly Sods area in West Virginia, a broad, rocky plateau at an elevation of about ; Dan's Rock on Dans Mountain in Maryland at ; and Blue Knob in northern
Bedford County, Pennsylvania Bedford County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 47,577. The county seat is Bedford. History In 1750 Robert MacRay, a Scots-Irish immigrant, opened the first trading post in Raystown ...
, 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
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#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...
and the
Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an 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 the United S ...
separates the westward-flowing Ohio River watershed from the eastward-flowing watersheds of the Susquehanna, Potomac, and James 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. It is the primary city of the Cumberland, MD-WV Metropolitan Statistical Area. At the 2020 census, the city had a population of 19,076. Located on the Potomac River, ...
, which originates well into 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 no ...
at the Fairfax Stone, just south of Maryland's southwestern tip. No waterway crosses the Front from east to west.


Course in detail

The Allegheny Front begins in central Pennsylvania just northwest of the town of Lock Haven 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 Brush Mountain may refer to: United States The USGS Geographical Names Information System lists 35 summits, including: Other countries * Brush Mountain (Alberta) Brush Mountain may refer to: United States The US ...
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 Virgini ...
in Maryland, the Front becomes Dans Mountain, west of Cumberland, 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
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, i ...
. South of the Potomac, in West Virginia, the Front continues through the Mount Storm area, then passes along the eastern edge of Dolly Sods, a wide plateau of Pottsville conglomerate
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 ...
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 The Roaring Plains West Wilderness is a U.S. Wilderness Area in the Allegheny Mountains of eastern West Virginia, USA. It is part of the Monongahela National Forest and includes Mount Porte Crayon, the sixth highest point in the state. Known as ...
continuing the high plateaus of the Dolly Sods area along the escarpment's crest. The Allegheny Front's southern end is
Mount Porte Crayon Mount Porte Crayon is a mountain in the Roaring Plains Wilderness of the Monongahela National Forest in the northeastern corner of Randolph County, West Virginia, USA. It rises to an elevation of , the elevational climax of the Allegheny Front. T ...
(), after which the land drops steeply to Seneca Creek, west of Seneca Rocks.


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, 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 (along with the southern end of Shavers Mountain), 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 () 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 ...
(); 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-c ...
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 Pottsville conglomerate, sometimes where flat with younger Carboniferous 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 o ...
-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 classif ...
-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 19 ...
about 320-250 million years ago, during the Carboniferous 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 Pale ...
geological periods, forming the modern
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. The ...
as the ancient continents of North America 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 di ...
(for more than 200,000,000 years) has preferentially removed various softer surrounding rocks, especially the easily dissolved Greenbrier limestone, leaving areas of the hard Pottsville conglomerate as a caprock protecting softer rock strata immediately beneath. The Pottsville
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 ...
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 Dolly Sods and an overlook along U.S. Route 50 in West Virginia. Since the eastern side of the Front is drained by
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 ...
rivers that drop fairly rapidly through the Ridge and Valley Province 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 ...
, 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 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 , lor ...
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 Atlant ...
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 Dolly Sods, 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 Dolly Sods area of West Virginia, and southward toward
Mount Porte Crayon Mount Porte Crayon is a mountain in the Roaring Plains Wilderness of the Monongahela National Forest in the northeastern corner of Randolph County, West Virginia, USA. It rises to an elevation of , the elevational climax of the Allegheny Front. T ...
, 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) 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, ...
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 regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. ...
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 co ...
. 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 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 U.S. Route 50 in West Virginia 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 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 year. W ...
s along of the Allegheny Front in Grant County near Mount Storm. Constructed between 2006 and 2008, it generates up to 264
megawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after Jame ...
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