The Allegheny Front is the major southeast- or east-facing
escarpment in the
Allegheny Mountains 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 t ...
, 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 Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
, USA. The Allegheny Front forms the boundary between the
Ridge-and-Valley Appalachians to its east and the
Appalachian Plateau (locally called the
Allegheny Plateau) 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. Miss ...
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 ...
, 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 region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
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 near the southwestern tip of Maryland, about and across the actual divide from the headwaters of the
Youghiogheny River draining 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. Miss ...
, leading to the recent establishment of
wind farming there.
Geography
The Allegheny Front forms part of the
Appalachian Structural Front, separating the
Appalachian Plateau from the Appalachians'
Ridge and Valley Province.
The various other
escarpments 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
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, ...
through
western Maryland, 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 sourc ...
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. ...
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. 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, 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's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
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 ...
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, which originates well into the
Appalachian Plateau 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 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
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.
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 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
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. ...
(), 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
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 All ...
(); these two mountains form a part of the divide between the
Monongahela River 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 ...
-cemented
gravel-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 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 Paleo ...
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
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 th ...
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 d ...
(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 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 region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
rivers that drop fairly rapidly through the
Ridge and Valley Province to the low-elevation waters of the
Great Appalachian Valley, 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 t ...
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 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. ...
, 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
Appalachian and
boreal
Boreal may refer to:
Climatology and geography
*Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch
*Boreal climate, a climate characterized by long winters and short, cool to mild ...
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 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 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. ...
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 James ...
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