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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 developed eras. The Allegheny Mountains have a northeast–southwest orientation, running for about 300 mi from north-central Pennsylvania southward, through western Maryland and eastern West Virginia.

The Alleghenies comprise the rugged western-central portion of the Appalachians. They rise to approximately 4,862 ft in northeastern West Virginia. In the east, they are dominated by a high, steep escarpment known as the Allegheny Front. In the west, they slope down into the closely associated Allegheny Plateau, which extends into Ohio and Kentucky. The principal settlements of the Alleghenies are Altoona, State College, and Johnstown, Pennsylvania; and Cumberland, Maryland.

Using the USGS classification of physical geography (physiography), the Allegheny Mountain range is part of the Appalachian Plateau province of the Appalachian Highlands physiographic division.

Etymology
The name is derived from the Allegheny River, which drains only a small portion of the Alleghenies in west-central Pennsylvania. The meaning of the word, which comes from the Lenape (Delaware) Native Americans, is not definitively known but is usually translated as "fine river". The closest approximation which makes sense is some context from the Jesuit Relations showing that Alligeh was one of several accepted renderings of the name of the Erie people among the early 17th century missionaries among the Native peoples throughout the eastern Great Lakes region, along with Rique, Yenresh and Erichronon. The suffix -ni means "of the," in Lenape, despite the irony that geh is also Iroquoian for "of the." So, most likely, Alligehni, or Oligini, would probably be the Lenape name for the original homeland of the Erie people.

The word "Allegheny" was once commonly used to refer to the whole of what are now called the Appalachian Mountains. John Norton used it (spelled variously) around 1810 to refer to the mountains in Tennessee and Georgia. Around the same time, Washington Irving proposed renaming the United States either "Appalachia" or "Alleghania". In 1861, Arnold Henry Guyot published the first systematic geologic study of the whole mountain range. His map labeled the range as the "Alleghanies", but his book was titled On the Appalachian Mountain System. As late as 1867, John Muir—in his book A Thousand Mile Walk to the Gulf—used the word "Alleghanies" in referring to the southern Appalachians.

There was no general agreement about the "Appalachians" versus the "Alleghanies" until the late 19th century.

Extent
From northeast to southwest, the Allegheny Mountains run about 300 mi. From west to east, at their widest, they are about 100 mi. When combining the Allegheny Province with the Kanawa Province, they run 400 mi.

The USGS physiographic classification of all land in the United States lists the Allegheny Mountains as a section within the larger Appalachian Plateau province. It may generally defined to the south by the Allegheny Front, and to the east by the Susquehanna River valley. To the west, the Alleghenies grade down into the dissected Allegheny Plateau. The westernmost ridges are considered to be the Laurel Highlands and Chestnut Ridge in Pennsylvania, and Laurel Mountain and Rich Mountain in West Virginia.

Big Stone Ridge marks the southern extent of the Alleghenies and is an outlier of Flat Top Mountain, with the Tug Fork river running along its western flank. The land to the south and to the west of the Alleghenies is the Valley and Ridge physiographic province.

Allegheny Front and Allegheny Highlands
The eastern edge of the Alleghenies is marked by the Allegheny Front, which is also sometimes considered the eastern terminus of the Allegheny Plateau. This great escarpment roughly follows a portion of the Eastern Continental Divide in this area. A number of impressive gorges and valleys drain the Alleghenies: to the east, Smoke Hole Canyon (South Branch Potomac River), and to the west the New River Gorge and the Blackwater and Cheat Canyons. Thus, about half the precipitation falling on the Alleghenies makes its way west to the Mississippi and half goes east to Chesapeake Bay and the Atlantic seaboard.

The highest ridges of the Alleghenies are just west of the Front, which has an east/west elevational change of up to 3000 ft. Absolute elevations of the Allegheny Highlands reach nearly 5000 ft, with the highest elevations in the southern part of the range. The highest point in the Allegheny Mountains is Spruce Knob (4,863 ft), on Spruce Mountain in West Virginia. Other notable Allegheny highpoints include Thorny Flat on Cheat Mountain (4,848 ft), Bald Knob on Back Allegheny Mountain (4,842 ft), and Mount Porte Crayon (4,770 ft), all in West Virginia; Dans Mountain (2,898 ft) in Maryland, Backbone Mountain (3360 ft), the highest point in Maryland; Mount Davis (3,213 ft), the highest point in Pennsylvania, and the second highest, Blue Knob (3,146 ft).

Development
There are very few sizable cities in the Alleghenies. The four largest are (in descending order of population): Altoona, State College, Johnstown (all in Pennsylvania) and Cumberland (in Maryland). In the 1970s and '80s, the Interstate Highway System was extended into the northern portion of the Alleghenies, and the region is now served by a network of federal expressways—Interstates 80, 70/76 and 68. Interstate 64 traverses the southern extremity of the range, but the Central Alleghenies (the "High Alleghenies" of eastern West Virginia) have posed special problems for highway planners owing to the region's very rugged terrain and environmental sensitivities (see Corridor H). This region is still served by a rather sparse secondary highway system and remains considerably lower in population density than surrounding regions.

In the telecommunications field, a unique impediment to development in the central Allegheny region is the United States National Radio Quiet Zone (NRQZ), a large rectangle of land—about 13000 sqmi—that straddles the border area of Virginia and West Virginia. Created in 1958 by the Federal Communications Commission, the NRQZ severely restricts all omnidirectional and high-power radio transmissions, although cell phone service is allowed throughout much of the area.

Protected areas
Much of the Monongahela (West Virginia), George Washington (West Virginia, Virginia) and Jefferson (Virginia) National Forests lie within the Allegheny Mountains. (No part of the wooded Alleghenies in Maryland or Pennsylvania, however, is managed by the U.S. Forest Service.) The Alleghenies also include a number of federally designated wilderness areas, such as the Dolly Sods Wilderness, Laurel Fork Wilderness, and Cranberry Wilderness in West Virginia.

The mostly completed Allegheny Trail, a project of the West Virginia Scenic Trails Association since 1975, runs the length of the range within West Virginia. The northern terminus is at the Mason–Dixon line and the southern is at the West Virginia-Virginia border on Peters Mountain.

Geology
The bedrock of the Alleghenies is mostly sandstone and metamorphosed sandstone, quartzite, which is extremely resistant to weathering. Prominent beds of resistant conglomerate can be found in some areas, such as the Dolly Sods. When it weathers, it leaves behind a pure white quartzite gravel. The rock layers of the Alleghenies were formed during the Appalachian orogeny.

Because of intense freeze-thaw cycles in the higher Alleghenies, there is little native bedrock exposed in most areas. The ground surface usually rests on a massive jumble of sandstone rocks, with air space between them, that are gradually moving down-slope. The crest of the Allegheny Front is an exception, where high bluffs are often exposed.

Mineral springs in the High Alleghenies attracted Native Americans and 18th century white settlers and provided a modest incentive to the local economy. The spas developing around these geological features include celebrated resorts that continue to cater to an exclusive clientele, such as The Greenbrier (White Sulphur Springs, West Virginia; hotel built 1858) and The Homestead (Hot Springs, Virginia; original lodge built 1766).

Flora
The High Alleghenies are noted for their forests of red spruce, balsam fir, and mountain ash, trees typically found much farther north. Hardwood forests also include yellow birch, sugar and red maple, eastern hemlock, and black cherry. American beech, pine and hickory can also be found. The forests of the entire region are now almost all second- or third-growth forests, the original trees having been removed in the late 19th and (in West Virginia) early 20th centuries. The wild onion known as the ramp (Allium tricoccum) is also present in the deeper forests.

Certain isolated areas in the High Alleghenies are well known for their open expanses of sphagnum bogs and heath shrubs (e.g., Dolly Sods, Cranberry Glades). Many plant communities are indeed similar to those of sea-level eastern Canada. But the ecosystems within the Alleghenies are remarkably varied. In recent decades, the many stages of ecologic succession throughout the area have made the region one of enduring interest to botanists.

Fauna
The larger megafauna which once inhabited the High Alleghenies—elk, bison, mountain lion—were all exterminated during the 19th century. They survived longer in this area, however, than in other parts of the eastern United States. Naturalist John James Audubon reported that by 1851 a few eastern elk (Cervus canadensis canadiensis) could still be found in the Alleghany Mountains but that by then they were virtually gone from the remainder of their range. Mammals in the Allegheny region today include whitetail deer, chipmunk, raccoon, skunk, groundhog, opossum, weasel, field mouse, flying squirrel, cottontail rabbit, gray foxes, red foxes, gray squirrels, red squirrels and a cave bat. Bobcat, snowshoe hare, wild boar and black bear and coyote are also found in the forests and parks of the Alleghenies. Mink and beaver are much less often seen.

These mountains and plateau have over 20 species of reptiles represented as lizard, skink, turtle and snake. Some of the icterid birds visit the mountains as well as the hermit thrush and wood thrush. North American migrant birds live throughout the mountains during the warmer seasons. Occasionally, osprey and eagles can be found nesting along the streams. The hawks and owls are the most common birds of prey.

The water habitats of the Alleghenies hold 24 families of fish. Amphibian species number about 21, among them hellbenders, lungless salamanders, and various toads and frogs. The Alleghenies provide habitat for about 54 species of common invertebrate. These include Gastropoda, slugs, leech, earthworms and grub worm. Cave crayfish (Cambarus nerterius) live alongside a little over seven dozen cave invertebrates.

Pre-contact Native Americans
The indigenous people inhabiting the Allegheny Mountains emerged from the greater region's archaic and mound building cultures, particularly the Adena and Eastern Woodland peoples with a later Hopewellian influence. These Late Middle Woodland culture people have been called the Montaine (c. A.D. 500 to 1000) culture. Their neighbors, the woodland Buck Garden culture, lived in the western valleys of the central Allegheny range. The Montaine sites extend from the tributaries of the upper Potomac River region south to the New River tributaries. These also were influenced by the earlier Armstrong culture of the more southwestern portions northern sub-range of the Ouasioto (Cumberland) Mountains and by the more easterly Virginia Woodland people. The Late Woodland Montaine were less influenced by Hopewellian trade from Ohio, although similarly polished stone tools have been found among the Montaine sites in the Tygart Valley. Small groups of Montaine people appear to have lingered much beyond their classically defined period in parts of the most mountainous valleys.

The watershed of the Monongahela River is within the northwestern Alleghenies, and it is from it that the Monongahela culture takes its name. The Godwin-Portman site (36AL39) located in Allegheny County, Pennsylvania, had a possible Fort Ancient (c. AD 850 to 1680) presence during the 15th century. Washington Boro ceramics have been found on the Barton (18AG3) and Llewellyn (18AG26) sites in Maryland on the northeastern slopes of the late Susquehannock sequence. The early Monongahela (c. AD 900 to 1630) are called the Drew Tradition in Pennsylvania. According to archeologist Richard L. George: "I believe that some of the Monongahela were of Algonquin origin.... Other scholars have suggested that Iroquoian speakers were interacting with Late Monongahela people, and additional evidence is presented to confirm this. I conclude that the archaeologically conceived term, Monongahela, likely encompasses speakers of several languages, including Siouan." According to Dr Maslowski of West Virginia in 2009: "The New River Drainage and upper Potomac represents the range of the Huffman Phase (Page) hunting and gathering area or when it is found in small amounts on village sites, trade ware or Page women being assimilated into another village (tribe)." Finally, according to Prof Potter of Virginia, they [the people represented by the Huffman Phase of Page pottery] had occupied the eastern slopes of the Alleghenies on the upper Potomac to the northern, lower Shenandoah Valley region before the A.D. 1300 Luray phase (Algonquian) peoples' "invasion". It is thought that these ancient Alleghenians were pushed from the classic Huffman Phase of the eastern slopes of the Alleghenies to the Blue Ridge Mountains in western Virginia, which was eastern Siouan territory.

In 1669, John Lederer and members of his party became the first Europeans to crest the Blue Ridge Mountains and the first to see the Shenandoah Valley and the Allegheny Mountains beyond.

Native Americans in the 17th century
The proto-historic Alleghenies can be exampled by the earliest journals of the colonists. According to Batts and Fallows' September, 1671 Expedition, they found Mehetan Indians of Mountain "Cherokee-Iroquois" mix on the New River tributaries. This journal does not identify the "Salt Village", but, that the "Mehetan" were associated with these and today thought to be "Monetons", Siouans. However, this journal does not identify the "Salt Village" below the Kanawha Falls, but, that simply the "Mehetan" were associated with these. He explained, below the "Salt Villages", a mass of hostile Indians had, implied, arrived and some believe these to be "Shanwans" of Vielles Expedition of 1692~94, ancient Shawnee. In 1669, John Lederer of Maryland for the Virginia Colony and the Tennessee Cherokee had visited the mouth of the Kanawha and reported no hostilities on the lower streams of the Alleghenies. The Mohetan representative through a Siouan translator explained to Mr Batts and Mr Fallon, Colonel Abraham Woods explorers 1671–2, that he (Moheton Native American) could not say much about the people below the "Salt Village" because they (Mountain Cherokee) were not associated with them. The Mohetan was armed by this time of 1671 for the Mohetan Representative was given several pouches of ammunition for his and the other's weapons as a token of friendship. Somebody had already been trading within the central Alleghenies before the Virginians historical record begins in the Allegheny Mountains. Some earlier scholars found evidence these Proto-historics were either Cistercians of Spanish Ajacan Occuquan outpost on the Potomac River or Jesuits and their Kahnawake Praying Indians (Mohawk) on the Riviere de la Ronceverte. The "Kanawha Madonna" may date from this period or earlier. Where the New River breaks through Peters' Mountain, near Pearisburg Virginia the 1671 journal mentions the "Moketans had formerly lived".

According to a number of early 17th century maps, the Messawomeake or "Mincquas" (Dutch) occupied the northern Allegheny Mountains. The "Shatteras" (an ancient Tutelo) occupied the Ouasioto Mountains and the earliest term Canaraguy (Kanawhans otherwise Canawest ) on the 1671 French map occupied the southerly Alleghenies. They were associated with the Allegheny "Cherokee" and Eastern Siouan as trade-movers and canoe transporters. The Calicuas, an ancient most northern Cherokee, migrated or was pushed from the Central Ohio Valley onto the north eastern slopes of the Alleghenies of the ancient Messawomeake, Iroquois tradesmen to 1630s Kent Island, by 1710 maps. Sometime before 1712, the Canawest ("Kanawhans"-"Canallaway"-"Canaragay") had moved to the upper Potomac and made a Treaty with the newly established trading post of Fort Conolloway which would become a part of western Maryland during the 1740s.

Trading posts and other settlements
Prior to European exploration and settlement, trails through the Alleghenies had been transited for many generations by American Indian tribes such as the Iroquois, Shawnee, Delaware, Catawba and others, for purposes of trade, hunting and, especially, warfare. Western Virginia "Cherokee" were reported at Cherokee Falls, today's Valley Falls of the Tygart Valley. Indian trader Charles Poke's trading post dates from 1731 with the Calicuas of Cherokee Falls still in the region from the previous century.

The "London Scribes" (The Crown's taxation records) vaguely mentions the colonial Alleghenian location of only a few other early colonial trading locations. A general knowledge of these few outposts are more of traditional telling of some local people. However, an example is the "Van Metre" trading house mentioned in an earlier edition of the "Wonderful West Virginia Magazine" being on the South Branches of the upper reaches of the Potomac. Another very early trading house appears on a lower Greenbrier Valley map during the earlier decades of the 18th century.

As early as 1719, new arrivals from Europe began to cross the lower Susquehanna River and settle illegally in defiance of the Board of Property in Pennsylvania, on un-warranted land of the northeastern drainage rivers of the Allegheny Mountains. Several Indian Nations requested the removal of "Maryland Intruders". Some of these moved onward as territory opened up beyond the Alleghenies.

The first permanent European settlers west of the Alleghenies have traditionally been considered to have been two New Englanders: Jacob Marlin and Stephen Sewell, who arrived in the Greenbrier Valley in 1749. They built a cabin together at what would become Marlinton, West Virginia, but after disputing over religion, Sewell moved into a nearby hollowed-out sycamore tree. In 1751, surveyor John Lewis (father of Andrew Lewis) discovered the pair. Sewell eventually settled on the eastern side of Sewell Mountain, near present-day Rainelle, West Virginia. They may well have been the first to settle what was then called the "western waters"—i.e., in the regions where streams flowed westward to the Gulf of Mexico rather than eastward to the Atlantic.

First surveys
Among the first whites to penetrate into the Allegheny Mountains were surveyors attempting to settle a dispute over the extent of lands belonging to either Thomas Fairfax, 6th Lord Fairfax of Cameron or to the English Privy Council. An expedition of 1736 by John Savage established the location of the source of the North Branch Potomac River. In March 1742, a frontiersman named John Howard—along with his son and others—had been commissioned by Governor Gooch to explore the southwest of Virginia as far as the Mississippi River. Following Cedar Creek through the Natural Bridge, they floated in buffalo-skin boats down the New, Coal, Kanawha, and Ohio Rivers to the Mississippi. Although captured by the French before he reached Natchez, Howard was eventually released and (in 1745) was interviewed by Fairfax. Howard's description of the South Branch Potomac River resulted in the definite decision by Fairfax to secure his lands in the region. An expedition under Peter Jefferson and Thomas Lewis in the following year emplaced the "Fairfax Stone" at the source of the North Branch and established a line of demarcation (the "Fairfax Line") extending from the stone south-east to the headwaters of the Rappahannock River. Lewis' journal of that expedition provides a valuable view of the Allegheny country before its settlement. Jefferson and Joshua Fry's "Fry-Jefferson Map" of 1751 accurately depicted the Alleghenies for the first time. In the following decades, pioneer settlers arrived in the Alleghenies, especially during Colonial Virginia's Robert Dinwiddie era (1751–58). These included squatters by the Quit-rent Law. Some had preceded the official surveyors using a "hack on the tree and field of corn" marking land ownership approved by the Virginia Colonial Governor who had to be replaced with Governor John Murray, 4th Earl of Dunmore.

First roads

Trans-Allegheny travel had been facilitated when a military trail—Braddock Road—was blazed and opened by the Ohio Company in 1751. (It followed an earlier Indian and pioneer trail known as Nemacolin's Path.) Braddock Road connected Cumberland, Maryland (the upper limit of navigation on the Potomac River) and the forks of the Ohio River (the future Pittsburgh, Pennsylvania). It received its name from the British leader of the French and Indian War (1754–63), General Edward Braddock, who led the ill-fated Braddock expedition four years later.

In addition to the war, hunting and trading with Indians were primary motivations for white movement across the mountains. Permanent white settlement of the northern Alleghenies was facilitated by the explorations and stories of such noted Marylanders as the Indian fighter and trader Thomas Cresap (1702–90) and the backwoodsman and hunter Meshach Browning (1781–1859). In the late 18th century, a massive migration to the Monongahela River basin took place over three main routes: along the old Braddock Road via Winchester, Virginia; through the Shenandoah Valley to the head of the Cheat River and from there to the Monongahela; and along the Lincoln Highway to Ligonier, Pennsylvania, and thence along Jacob's Creek to the Monongahela. These immigrants were predominantly Scotch-Irish, German, and, to a lesser extent, British stock.

The Braddock Road was superseded by the Cumberland Road—also called the National Road—one of the first major improved highways in the United States to be built by the federal government. Construction began in 1811 at Cumberland and the road reached Wheeling, Virginia (now West Virginia) on the Ohio River in 1818. Just to the south, the state-funded Staunton and Parkersburg Turnpike was constructed to provide a direct route for the settlements of the Shenandoah Valley to the Ohio River by way of the Tygart Valley and Little Kanawha Rivers. Planned and approved in 1826 and completed in 1848, the Staunton and Parkersburg was maintained by fees (tolls) collected at toll houses placed at regular intervals.

First railroads and canals
Construction on the Baltimore and Ohio Railroad began at Baltimore in 1828; the B&O traversed the Alleghenies, changing the economy and society of the Mountains forever. The B&O had reached Martinsburg, (West) Virginia by May 1842, Hancock, (West) Virginia, by June, Cumberland, Maryland, on November 5, 1842, Piedmont, (West) Virginia on July 21, 1851, and Fairmont, (West) Virginia on June 22, 1852. (It finally reached its Ohio River terminus at Wheeling, (West) Virginia on January 1, 1853.)

The Chesapeake and Ohio Canal—also begun in 1828, but at Georgetown—was also a public work of enormous economic and social significance for the Alleghenies. It approached Hancock, Maryland, by 1839. From the beginning, the B&O Railroad and the Chesapeake and Ohio Canal operated in bitter legal and commercial competition with one another as they vied for rights to the narrow strips of land along the Potomac. When the Canal finally reached Cumberland in 1850, the Railroad had already arrived eight years before. Debt-ridden, the Canal company dropped its plan to continue construction of the next 180 mi of the Canal into the Ohio Valley. The company had long realized—especially with the difficult experience of digging the Paw Paw Tunnel—that the original plan of construction over the mountains and all the way down the Youghiogheny River to Pittsburgh was "wildly unrealistic".

Public works financed at the state level were not lacking during this period. The Main Line of Public Works was a railroad and canal system across southern Pennsylvania between Philadelphia and Pittsburgh. Built between 1826 and 1834 by the Commonwealth of Pennsylvania, it included the Philadelphia and Columbia Railroad, the Allegheny Portage Railroad and the Pennsylvania Canal system.

Civil War
Lying astride the border separating the Union and Confederacy, the Alleghenies were among the areas most directly affected by the American Civil War (1861–1865). One of the earliest campaigns of the War was fought for control of the Staunton and Parkersburg Turnpike and for the access it provided to the B&O Railroad. The Battle of Rich Mountain (July 11, 1861) gave the Federals control of the turnpike, of Tygart's Valley, and of all of the territory of western Virginia to the north and west, including the railroad. (Union General George McClellan's victory in this theater would ultimately bring him promotion to commander the Army of the Potomac.) The Federals fortified at Cheat Summit, and the Confederates established strongholds at Camp Bartow and Camp Allegheny. Here they faced each other warily through the fall of 1861 and the following winter. General Robert E. Lee's attempt to attack Cheat Summit Fort (September 12–15, 1861) and Federal attempts to attack Bartow and Allegheny, all failed to change the strategic stalemate. Finally, the harsh, high elevation winter achieved what the troops had failed to accomplish, and in the spring of 1862 both armies moved on down the pike to the Battle of McDowell (May 8, 1862), and then on to fight what became General Stonewall Jackson's Shenandoah Valley Campaign (spring 1862). Two years later, much of this contested area (along with much else) became part of the new state of West Virginia. The very rugged terrain of the Alleghenies was not at all amenable to a large-scale maneuver war and so the actions that the area witnessed for the remainder of the conflict were generally guerrilla in nature.

Coal and timber industries
With the further spread of the railroad networks in the 1890s and early 1900s, many new towns developed and thrived in the Alleghenies. The lumbering and coal industries that boomed in the wake of the railroads brought a measure of prosperity to the region, but most of the revenues flowed out of the mountains to the cities of the eastern seaboard where the captains of industry were headquartered. This inequity created a bitter legacy that would last for generations and form the foundation of the mountaineers' poverty and the area's immense environmental degradation.

The most momentous disaster to afflict the people of the Alleghenies was the Johnstown Flood—locally known as the "Great Flood of 1889"—which occurred on May 31 of that year after the catastrophic failure of the South Fork Dam on the Little Conemaugh River 14 mi upstream of the town of Johnstown, Pennsylvania. The dam broke after several days of extremely heavy rainfall, unleashing 20 million tons of water (18 million cubic meters) from the reservoir known as Lake Conemaugh. (This body of water had been built as part of the Main Line of Public Works, then abandoned.) With a flow rate that temporarily equalled that of the Mississippi River, the flood killed 2,209 people and caused US$17 million of damage (about $425 million in 2012 dollars). The American Red Cross, led by Clara Barton and with 50 volunteers, undertook a major disaster relief effort. Support for victims came from all over the United States and 18 foreign countries. After the flood, survivors suffered a series of legal defeats in their attempts to recover damages from the dam's owners. Public indignation at that failure prompted the development in American law changing a fault-based regime to strict liability.

20th century
In the 1920s and '30s, Allegheny highways were extensively paved to provide access for automobiles.

From the 1950s to 1992, the United States government maintained a top secret continuity program known as Project Greek Island at The Greenbrier hotel in the Alleghenies of southern West Virginia.

In August 1963, at the March on Washington for Jobs and Freedom, Dr. Martin Luther King Jr. referenced the Alleghenies—among several in an evocative list of mountains—in his famous "I Have a Dream" speech, when he said "Let freedom ring from the heightening Alleghenies of Pennsylvania!"

21st century
The Flight 93 National Memorial is located at the site of the crash of United Airlines Flight 93—which was hijacked in the September 11 attacks—in Stonycreek Township, Pennsylvania, about 2 mi north of Shanksville. The memorial honors the passengers and crew of Flight 93, who stopped Al-Qaeda terrorists from reaching their intended target.

Folklore

 * McNeill, G.D. (Douglas), The Last Forest, Tales of the Allegheny Woods, n.p., 1940. (Reprinted with preface by Louise McNeill, Pocahontas Communications Cooperative Corporation, Dunmore, W. Va. and McClain Printing Company, Parsons, W. Va, 1989.)

Botany

 * Core, Earl L. (1967), "Wildflowers of the Alleghenies", J. Alleghenies, 4(l):I, 2–4.
 * Core, Earl L. (1943), "Botanizing in the Higher Alleghenies", Sci. Monthly, 57:119-125.

title: Allegheny Mountains


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Trinity University (Texas)

Trinity University is a private liberal arts college in San Antonio, Texas. Founded in 1869, its student body consists of about 2,600 undergraduate and 200 graduate students. Trinity offers 49 majors and 61 minors among six degree programs, and has an endowment of $1.725 billion.

History
Cumberland Presbyterians founded Trinity in 1869 in Tehuacana, Texas, from the remnants of three small Cumberland Presbyterian colleges that had lost significant enrollment during the Civil War: Chapel Hill College (founded 1849), Ewing College (founded 1848), and Larissa College (founded 1855). John Boyd, who had served in the Congress of the Republic of Texas from 1836 to 1845 and in the Texas Senate from 1862 to 1863, donated 1,100 acres of land and financial assistance to establish the new university.

Believing that the school needed the support of a larger community, the university moved in 1902 to Waxahachie, Texas. In 1906, the university, along with many Cumberland Presbyterian churches, affiliated with the United Presbyterian Church. The Stock Market Crash of 1929, however, severely hindered the university's growth. Enrollment declined sharply, indebtedness and faculty attrition mounted, and trustees began using endowment funds to maintain daily operations. Consequently, the Southern Association of Colleges and Schools placed Trinity's accreditation status on probation in 1936, jeopardizing its future. Once again, its leaders began to consider relocation to a larger community to improve the university's viability.

Meanwhile, in 1942, the Methodist-affiliated University of San Antonio was failing. San Antonio community leaders, who wished to maintain a Protestant-affiliated college in the city, approached Trinity with a relocation offer. The university left Waxahachie and took over the campus and alumni of the University of San Antonio. (The old Waxahachie campus is currently home to Southwestern Assemblies of God University). For the next decade, the Woodlawn campus, on the city's near-west side, was Trinity's home while it developed a permanent home. Lacking adequate facilities, the university functioned by using military barracks and quonset huts to house students and to provide library and classroom space.

In 1945, Trinity acquired a former limestone quarry for a new campus and hired Texas architect O'Neil Ford to design a master plan and many of the buildings. Construction began in 1950, and the current campus opened in 1952.

When it moved, the campus was largely undeveloped (one classroom building, one dorm, and a nearly empty library were the only completed buildings). Yet, under the leadership of James W. Laurie, the university's 14th president, Trinity took advantage of its new location in a rapidly growing major urban center to grow in academic stature. Laurie was responsible for drastically increasing Trinity's endowment, largely funded by the James A. and Leta M. Chapman Charitable Trust of Tulsa, Oklahoma. The stronger endowment allowed Trinity to construct a new, modern campus on its "University on the Hill" location and to increase the quality and range of its faculty while maintaining a high faculty to student ratio. In 1969, Trinity entered into a covenant agreement with the regional synod of the Presbyterian Church (USA) that affirmed historical connections, but transformed Trinity into a private, independent university with a self-perpetuating board of trustees. The campus continues to be a "historically connected" member of the Association of Presbyterian Colleges and Universities.

Trinity's growth continued under Ronald Calgaard, who followed Laurie's successor, Duncan Wimpress. Under Calgaard, the university implemented a number of changes to raise its profile. For example, Trinity transformed into a residential undergraduate school, requiring all freshmen to live on campus and cutting the number of master's programs offered from more than 20 to four. Also, Trinity decreased its student population from about 3,300 to 3,000 (and eventually to 2,700), increased merit scholarships, increased the focus on national student recruitment, and began scheduling a strong series of speakers and cultural events open to the public.

Calgaard's successor, John R. Brazil, focused on replacing outdated campus buildings and improving the school's financial resources. The "Campaign for Trinity University", which launched in September 2005, sought to raise US$200 million for a variety of purposes. At its conclusion on September 25, 2009, the campaign raised $205.9 million, surpassing the original goal. Brazil served as Trinity's president through January 2010. Upon announcement of his retirement, the board of trustees awarded him its Distinguished Service Award, Trinity's most prestigious honor.

Dennis A. Ahlburg served as president from January 2010 to January 2015. During Ahlburg's presidency, Trinity developed and executed a strategic plan to shape the future of the university. Academically, Trinity refined its curriculum to further define a liberal arts education, developed an entrepreneurship program, and realigned the business program. Trinity also refocused its marketing to raise the university's national profile. Finally, under Ahlburg, Trinity built the Center for Sciences and Innovation, which modernized and combined science facilities to ease collaboration across disciplines.

Danny J. Anderson, a Latin American literature scholar and dean of the College of Liberal Arts and Sciences at the University of Kansas, succeeded Ahlburg as president in May 2015, serving until May 31, 2022. During his tenure, improvements included the construction of Dicke Hall, home for Humanities studies; transformation of the Halsell Center into a modern learning environment, and creation of the Michael Neidorff School of Business, an AACSB-accredited undergraduate business school. The school was named a National Historic District during Anderson's tenure. Anderson also implemented several initiatives aimed at increasing the school's inclusivity, and by the end of his term 40% of Trinity's student body came from underrepresented backgrounds.

Vanessa Beasley, former vice provost for academic affairs, dean of residential faculty, and associate professor of communication studies at Vanderbilt University was named Anderson's successor on May 31, 2022. She will be the first female to lead Trinity and began her term at the beginning of the 2022–23 school year. Megan Mustain, provost and vice president for academic affairs, was interim president until then.

Campus
Trinity overlooks downtown San Antonio and is adjacent to the Monte Vista Historic District and just south of the cities of Olmos Park and Alamo Heights. The 125 acre Skyline Campus, the university's fourth location, is noted for its distinctive red-brick architecture and well-maintained grounds, modeled after an Italian village, by late architect O'Neil Ford.

Sustainability
The environmental movement at Trinity is known as Red Bricks, Green Campus. Trinity is a member of the Presidents' Climate Commitment and is actively working toward carbon neutrality. Trinity was ranked fifth in the RecycleMania Challenge. Students pushed for fair-trade options, and now all coffee sold at the university is certified fair trade. In 2011, Trinity University scored a B− on the College Sustainability Report Card, also known as the Green Report Card.

Miller Residence Hall, home to first-year students at Trinity University, was renovated and updated in 2010, earning gold Leadership in Energy and Environmental Design (LEED) certification by the U.S. Green Building Council in the process. In addition, Calvert Hall, the Thomas-Lightner complex, and The Center for the Sciences and Innovation have been registered with the Green Building Council's LEED program and are awaiting certification.

Notable buildings and structures

 * The 166 ft tall Murchison Tower is the most dominant landmark on the campus, designed, as many other buildings on campus, by O'Neil Ford, who also designed San Antonio landmark the Tower of the Americas a few years later based on this design. It was previously the highest point in San Antonio. The tower is now lit at night (excepting evenings when the lighting interferes with on-campus astronomical observances), a tradition begun on September 22, 2002, to commemorate Trinity's 60th anniversary in San Antonio.
 * Laurie Auditorium seats 2,865 and hosts both campus and community events. The university has many lecture series, such as the high-profile Trinity Distinguished Lecture Series, Stieren Arts Enrichment Series, Nobel Economists Lecture Series, and Flora Cameron Lecture on Politics and Public Affairs.

 * The 164000 sqft Elizabeth Huth Coates Library houses more than 1 million books and bound periodical volumes. The library, an advanced facility for a school of Trinity's size, also houses over 200,000 volumes of government documents, over 1.3 million microforms, over 65,000 media items, and maintains 2,400 periodical subscriptions and access to over 20,000 electronic periodicals. The library's annual acquisition budget is over US$1.8 million.
 * In 2006, the Ruth Taylor Fine Arts Center, consisting of the Jim and Janet Dicke Art Building, the Campbell and Eloise Smith Music Building, and the Ruth Taylor Recital Hall was substantially renovated under the guidance of Kell Muñoz Architects, providing 20,000 additional square feet of space. The building subsequently won a merit award for design from the City of San Antonio in 2008.
 * The Center for Sciences and Innovation (CSI), completed in 2014, modernized the university's science, engineering, and laboratory facilities and helped ease collaboration across disciplines. Renovations to connect existing buildings allow for a 300,000 square-foot science facility. The complex, certified LEED Gold, features a rooftop observatory, a living "green" roof and rooftop greenhouse, and an open-air innovation and design studio. The new building helped Trinity earn a top-five ranking in the Princeton Review for best science lab facilities.
 * The Margarite B. Parker Chapel seats six hundred and is known for its large Hofmann-Ballard pipe organ, the largest pipe organ in South Texas, comprising 5 divisions, 102 stops, 112 ranks, and over 6,000 pipes. A state-of-the-art four-manual console was installed in summer 2007, with the aid of the university's Calvert Trust Fund. Non-denominational services are led by the campus chaplain Sunday evenings.
 * In the Fall 2022, Trinity opened its latest building, Dicke Hall, which houses the Humanities Collective, the English Department, and the Religion Department. The building is 3 stories with 40,000 square feet, 6 classrooms, and 1 lecture hall. It was designed by the San Antonio architectural firm Lake Flato using a mass-timber structural system also known as Engineered wood.

Academics and rankings
As defined by the Carnegie Foundation's classification, Trinity University is a small, highly residential university with a majority of enrollments coming from undergraduate students. The full-time, four-year undergraduate program is classified as "more selective, lower transfer-in" and has an arts and sciences focus with some graduate student coexistence. Trinity is accredited by the Southern Association of Colleges and Schools and is a member of the Phi Beta Kappa Society. Full-time undergraduate tuition is $44,680 for the 2019–20 academic year; room and board are an additional $13,584.

Academics
Trinity offers 47 majors and 59 minors in the traditional liberal arts, business, sciences, fine arts, and engineering, and graduate programs in accounting, teaching, school psychology, school administration, and health care administration and is the only university in San Antonio to offer a minor in creative writing. Trinity stresses close interaction between students and faculty members across all disciplines, with a 9:1 student/faculty ratio. The full-time faculty numbers 228, 98% of whom hold a Ph.D. or other terminal degree in their field. About 47% of the student body has studied abroad in over 35 countries.

Its most popular undergraduate majors, based on 2021 graduates, were:
 * Research and Experimental Psychology (47)
 * Accounting (34)
 * Computer and Information Sciences (30)
 * Neuroscience (28)
 * Engineering Science
 * Finance (27)
 * Economics (27)

40 percent of students attend graduate school immediately after earning their bachelor's, and 65 percent of all students attend within five years of graduation.

An analysis by the Office of Institutional Research indicated that Trinity has made considerable progress in the number of graduates going on to earn doctoral degrees. Of students earning a bachelor's between 1982 and 1986, 2.9% went on to earn doctorates; of those earning a bachelor's between 1997 and 2001, 8.5% had. Trinity improved its ranking in this category from 328th to 38th among other colleges and universities.

Rankings

 * Trinity was ranked 1st overall in the West in U.S. News & World Report's 2021 "Regional University" rankings, 2nd for "Best Value", tied for 3rd for "Best Undergraduate Teaching", tied for 8th for "Most Innovative", and tied for 117th for "Top Performers on Social Mobility". Its undergraduate engineering program was ranked tied for 33rd out of 220 schools in the U.S. where doctorates are not offered.
 * Washington Monthly ranked Trinity 7th out of 614 master's universities in 2020 for "promoting the public good," based on social mobility, research, and civic engagement.
 * Kiplinger's Personal Finance places Trinity 37th in its 2019 ranking of 177 best value private universities in the United States.
 * Forbes ranks Trinity 110th nationally in its 2021 rankings of 650 colleges and universities. Forbes evaluates a college investment from a consumer perspective, focusing on the quality of teaching, career prospects, graduation rates, and levels of debt at graduation.
 * The Princeton Review recognized Trinity in its 2017 edition of The Best 381 Colleges, its annual college guide, and has been featured in the guide since its first publication.

Student body and admissions
Trinity's 2,582 undergraduate students come from 49 U.S. states plus 48 countries. Students of color account for 38.9 percent of undergraduate students. 72 percent of the undergraduate student body is from Texas; the next six states represented are California, Colorado, Louisiana, Arizona, and Missouri/Oregon.

The admissions office received 9,626 applications for the class of 2025 and accepted 34%. Test scores for the enrolled class of 2025 were 1300-1450 for the SAT and 29-33 for the ACT and 78 percent ranked in the top 20% of their high school graduating class.

Approximately 98 percent of the student body receives financial aid.

Greek life
Trinity hosts fourteen Greek organizations, seven fraternities and seven sororities. U.S. News & World Report estimates that 14% of men and 19% of women were members, or about 17% of total undergraduate enrollment. The current fraternities and sororities are as follows:

Fraternities:
 * Bengal Lancers
 * Chi Delta Tau
 * Iota Chi Rho
 * Kappa Kappa Delta
 * Omega Phi
 * Phi Sigma Chi
 * Triniteers

Sororities:
 * Alpha Chi Lambda
 * Chi Beta Epsilon
 * Delta Theta Nu
 * Gamma Chi Delta
 * Phi Delta Kappa
 * Sigma Theta Tau
 * Spurs
 * Zeta Chi

On occasion, fraternities and sororities have been mired in conflict at Trinity. In 1991, the New York Times reported that Trinity had discontinued campus Greek organizations right to pledge new members as a result of being in violation of the university's alcohol use policy. In 2012, two fraternities and two sororities had their charters temporarily revoked for hazing violations. These violations were said to have taken place over many years.

Student media
Trinity's radio station, KRTU-FM, broadcasts jazz during the day, and indie rock overnight. TigerTV serves as the campus TV station. In addition to movies, the channel broadcasts three main shows: Newswave, Studio 21, and the Not So Late Show. The Trinitonian has been the weekly campus newspaper for 103 years, and has a print circulation of 2,500.

Athletics
The Trinity Tigers is the nickname for the sports teams of Trinity University. They participate in the NCAA's Division III and the Southern Collegiate Athletic Conference (SCAC). The school mascot is LeeRoy, a Bengal tiger. In the 1950s, LeeRoy was an actual tiger who was brought to sporting events, but today LeeRoy is portrayed by a student wearing a tiger suit.

Trinity fields strong teams, evidenced by its finishes in the National Association of Collegiate Directors of Athletics (NACDA) Learfield Directors' Cup, which recognizes the strength of athletic programs by division. Since the Directors' Cup inception in 1995, Trinity has finished in the top 10 on five occasions out of over 400 Division Ill programs; it finished 31st in 2017–18.

Trinity has historically had a strong tennis program. In 1963, Al G. Hill Jr, grandson of oilman H L Hunt, entered as a Freshman Tennis Player. When he graduated in 1967 as Tiger Captain, the College Tennis Courts were named after him. Under the tutelage of Coach Clarence Mabry, Trinity Player Chuck McKinley won the Wimbledon Singles Championship in 1963 and was rated the #1 men's Singles Player in the World. With partner Dennis Ralston, McKinley won the US Men's Doubles Championship in 1961, 1963, and 1964. McKinley and Ralston also played all of the matches while winning the Davis Cup for the US in 1963. All of these accomplishments occurred while McKinley was a Trinity undergraduate.

In 1970, as a freshman at Trinity, Brian Gottfried won the USTA boys 18s Singles Championship, as well as the Doubles Championship with Alexander Mayer. In 1972 Trinity won the NCAA Division I Men's Tennis Championship. The Tiger Captain that year, Dick Stockton, won the NCAA Men's Singles Championship. The Women's Team won the NCAA Collegiate National championship in 1968, 1969, 1973, 1975, and 1976. As recently as 2000, the men's and women's programs each won NCAA Division III National Championships.

In the 2007 Trinity v. Millsaps football game on October 27, 2007, trailing by two points with two seconds left, the Tigers used 15 laterals covering 60 yards for a touchdown to give Trinity the win as time expired. The unlikely play was named the top sports moment of the year by Time Magazine as well as the "Game Changing Performance of the Year" by Pontiac.

In November 2015, Trinity and Austin College announced they would affiliate with the Southern Athletic Association for football in 2017. This alliance renews a relationship that ended when the SAA schools split from the SCAC. As a result, the SCAC will no longer offer football as a sport.

In May 2016, the Trinity Baseball Team won the Division III College World Series in a best-of-three format, beating Keystone College 14–6 in game 1 and 10–7 in game 2. Trinity defeated the 2015 champion, SUNY Cortland twice in the bracket rounds of the tournament en route to the championship.

Trinity also has won national championships in women's basketball (spring 2003) and men's soccer (fall 2003). Club sports include men's and women's tennis, lacrosse, water polo, fencing, ultimate frisbee, and trap and skeet.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Trinity University (Texas)


text:
Donghae Nambu Line

The Donghae Nambu Line is a railway line connecting Busan to Pohang in South Korea. The line runs along South Korea's east coast. On December 30, 2016, it was merged into Donghae Line.

History
On October 31, 1918, an extension of the Daegu Line reached Pohang. The section from Gyeongju to Pohang would become the oldest part of the future Donghae Nambu Line. On October 25, 1921, a branch of the Daegu Line from Gyeongju to Ulsan (Taehwagang) was opened. On December 16, 1935, Busan and Ulsan were linked up through the opening of the section Jwacheon–Ulsan. The new line and the two older sections built as part of the Daegu Line were combined into the new Donghae Nambu Line, with a length of 145.8 km from Busanjin to Pohang.

Upgrade
As of 2010, most of the line remains single-track and unelectrified. The entire line is to be upgraded to an electrified-double-tracked railway.

Busan–Ulsan
Planning for the upgrading of the line started in 1990 already, with the primary aim to improve commuter traffic; construction started in June 2003. The section gets a new 72.1 km long alignment with several tunnels. Korea Rail Network Authority, Busan, and Ulsan city government is undertaking the upgrade. As of 2010, construction progress reached 32% of the total budget of 2,268.9 billion won. The completion of the upgrade is foreseen for 2015.

On September 1, 2010, the South Korean government announced a strategic plan to reduce travel times from Seoul to 95% of the country to under 2 hours by 2020. As part of the plan, the Busan–Ulsan section of the Donghae Nambu Line is to be further upgraded for 230 km/h.

Ulsan–Gyeongju–Pohang
The line is to be replaced by a completely new alignment that circumvents downtown Gyeongju and connects to the Gyeongbu high-speed railway at Gyeongju station. In 2003, a feasibility study was prepared for the section. Detailed design was started, and in May 2007, the government expected to realise the project from 2008 to 2011 at the earliest. The project was finally approved by the government on April 23, 2009, and a ground-breaking ceremony was held. The altogether 76.56 km line was slated to be opened in December 2014, with a total budget of 2,328.899 billion won. In January 2010, the early completion of the Pohang branch was confirmed by the government.

Stations
Major stations and junctions along the line include (in order):

 * Busan station, terminus of the Gyeongbu Line;
 * Busanjin station, also on the Gyeongbu Line, just north of Busan Station;
 * Beomil station, terminus of the Gaya Line;
 * Bujeon station, terminus of the Bujeon Line;
 * Dongnae station
 * Sinhaeundae station, a popular resort beach in eastern Busan;
 * Gijang station
 * Namchang station, terminus of the Onsan Line;
 * Taehwagang station (formerly Ulsan), major industrial city and terminus of the Jangsaengpo and Ulsanhang Lines;
 * Gyeongju station, historic city and terminus of the Jungang Line;
 * Hyoja station, terminus of the Goedong Line; and
 * Pohang station, seaport and industrial city.

Services
The line sees passenger and freight traffic. As of October 2010, from Bujeon station in Busan, cross-country Mugunghwa-ho trains travel in around 1 hour 25 minutes to Ulsan and in around 2 hours 40 minutes to Pohang. Via the Gyeongbu, Daegu and Jungang Lines, Pohang and Ulsan are connected to Seoul with both intercity Saemaul-ho and cross-country Mugunghwa-ho services. As of 2010, the shortest travel times from Seoul to Pohang are around 5 hours 15 minutes by direct Saemaul service and around 3 hours 40 minutes with transfer to KTX trains at Dongdaegu.

After its upgrade is finished, the role of the line as a corridor for freight traffic will be enhanced.

Reuse abandoned old railroad of Donghae Nambu Line
This is an abandoned railroad. Between Ulsan and Busan Donghae Nambu Line a scrapped ship to utilize the space between East-Busan resort complex and that they would work together to Haeundae with connecting the invigoration of the local economy by creating a tourist resources. Haeundae Olympic Intersections created a green rail road that runs through Haeundae Station, the coastal spectacular Mi-po, Cheongsa-po, and Gudeok-po to provide pleasant and energetic spaces for tourists and local residents visiting Haeundae Beach.

Project

 * 1) Busan Green Rail Way Project 1  -  Section is from Haeundae Olympic Junction to Busan Mechanical Technical High School. Period is from Sep 23. 2015 to Dec. 29. 2016. Budget of this step is 3.41 Billion KRW.
 * 2) Busan Green Rail Way Project 2  -  Section is from Busan Mechanical Technical High School to East Busan Tourist District Entrance. Period is from Jun. 27. 2016 to Dec. 11. 2017. Budget of this step is 8.1 Billion KRW.

title: Donghae Nambu Line


text:
Internal conversion

Internal conversion is an atomic decay process where an excited nucleus interacts electromagnetically with one of the orbital electrons of an atom. This causes the electron to be emitted (ejected) from the atom. Thus, in internal conversion (often abbreviated IC), a high-energy electron is emitted from the excited atom, but not from the nucleus. For this reason, the high-speed electrons resulting from internal conversion are not called beta particles, since the latter come from beta decay, where they are newly created in the nuclear decay process.

IC is possible whenever gamma decay is possible, except if the atom is fully ionized. In IC, the atomic number does not change, and thus there is no transmutation of one element to another. Also, neutrinos and the weak force are not involved in IC.

Since an electron is lost from the atom, a hole appears in an electron aura which is subsequently filled by other electrons that descend to the empty, yet lower energy level, and in the process emit characteristic X-ray(s), Auger electron(s), or both. The atom thus emits high-energy electrons and X-ray photons, none of which originate in that nucleus. The atom supplies the energy needed to eject the electron, which in turn causes the latter events and the other emissions.

Since primary electrons from IC carry a fixed (large) part of the characteristic decay energy, they have a discrete energy spectrum, rather than the spread (continuous) spectrum characteristic of beta particles. Whereas the energy spectrum of beta particles plots as a broad hump, the energy spectrum of internally converted electrons plots as a single sharp peak (see example below).

Mechanism
In the quantum model of the electron, there is non-zero probability of finding the electron within the nucleus. In internal conversion, the wavefunction of an inner shell electron (usually an s electron) penetrates the nucleus. When this happens, the electron may couple to an excited energy state of the nucleus and take the energy of the nuclear transition directly, without an intermediate gamma ray being first produced. The kinetic energy of the emitted electron is equal to the transition energy in the nucleus, minus the binding energy of the electron to the atom.

Most IC electrons come from the K shell (the 1s state), as these two electrons have the highest probability of being within the nucleus. However, the s states in the L, M, and N shells (i.e., the 2s, 3s, and 4s states) are also able to couple to the nuclear fields and cause IC electron ejections from those shells (called L or M or N internal conversion). Ratios of K-shell to other L, M, or N shell internal conversion probabilities for various nuclides have been prepared.

An amount of energy exceeding the atomic binding energy of the s electron must be supplied to that electron in order to eject it from the atom to result in IC; that is to say, internal conversion cannot happen if the decay energy of the nucleus is less than a certain threshold.

Though s electrons are more likely for IC due to their superior nuclear penetration compared to electrons with greater orbital angular momentum, spectral studies show that p electrons (from shells L and higher) are occasionally ejected in the IC process. There are also a few radionuclides in which the decay energy is not sufficient to convert (eject) a 1s (K shell) electron, and these nuclides, to decay by internal conversion, must decay by ejecting electrons from the L or M or N shells (i.e., by ejecting 2s, 3s, or 4s electrons) as these binding energies are lower.

After the IC electron is emitted, the atom is left with a vacancy in one of its electron shells, usually an inner one. This hole will be filled with an electron from one of the higher shells, which causes another outer electron to fill its place in turn, causing a cascade. Consequently, one or more characteristic X-rays or Auger electrons will be emitted as the remaining electrons in the atom cascade down to fill the vacancies.

Example: decay of $203$Hg

The decay scheme on the left shows that $203$Hg produces a continuous beta spectrum with maximum energy 214 keV, that leads to an excited state of the daughter nucleus $203$Tl. This state decays very quickly (within 2.8×10$203$ s) to the ground state of $203$Tl, emitting a gamma quantum of 279 keV.

The figure on the right shows the electron spectrum of $−10$Hg, measured by means of a magnetic spectrometer. It includes the continuous beta spectrum and K-, L-, and M-lines due to internal conversion. Since the binding energy of the K electrons in $203$Tl is 85 keV, the K line has an energy of 279 − 85 = 194 keV. Due to lesser binding energies, the L- and M-lines have higher energies. Due to the finite energy resolution of the spectrometer, the "lines" have a Gaussian shape of finite width.

When the process is expected
Internal conversion is favored whenever the energy available for a gamma transition is small, and it is also the primary mode of de-excitation for 0$203$→0$203$ (i.e. E0) transitions. The 0$+$→0$+$ transitions occur where an excited nucleus has zero-spin and positive parity, and decays to a ground state which also has zero-spin and positive parity (such as all nuclides with even number of protons and neutrons). In such cases, de-excitation cannot take place by emission of a gamma ray, since this would violate conservation of angular momentum, hence other mechanisms like IC predominate. This also shows that internal conversion (contrary to its name) is not a two-step process where a gamma ray would be first emitted and then converted.

The competition between IC and gamma decay is quantified in the form of the internal conversion coefficient which is defined as $$\alpha = e/{\gamma}$$ where $$e$$ is the rate of conversion electrons and $$\gamma$$ is the rate of gamma-ray emission observed from a decaying nucleus. For example, in the decay of the excited state at 35 keV of $+$Te (which is produced by the decay of $+$I), 7% of decays emit energy as a gamma ray, while 93% release energy as conversion electrons. Therefore, this excited state of has an IC coefficient of $$\alpha = 93/7 = 13.3$$.

For increasing atomic number (Z) and decreasing gamma-ray energy, IC coefficients increase. For example, calculated IC coefficients for electric dipole (E1) transitions, for Z = 40, 60, and 80, are shown in the figure.

The energy of the emitted gamma ray is a precise measure of the difference in energy between the excited states of the decaying nucleus. In the case of conversion electrons, the binding energy must also be taken into account: The energy of a conversion electron is given as $$E = (E_i - E_f)-E_B$$, where $$E_i$$ and $$E_f$$ are the energies of the nucleus in its initial and final states, respectively, while $$E_B$$ is the binding energy of the electron.

Similar processes
Nuclei with zero-spin and high excitation energies (more than about 1.022 MeV) also can't rid themselves of energy by (single) gamma emission due to the constraint imposed by conservation of momentum, but they do have enough decay energy to decay by pair production. In this type of decay, an electron and positron are both emitted from the atom at the same time, and conservation of angular momentum is solved by having these two product particles spin in opposite directions.

IC should not be confused with the similar photoelectric effect. When a gamma ray emitted by the nucleus of an atom hits another atom, it may be absorbed producing a photoelectron of well-defined energy (this used to be called "external conversion"). In IC, however, the process happens within one atom, and without a real intermediate gamma ray.

Just as an atom may produce an IC electron instead of a gamma ray if energy is available from within the nucleus, so an atom may produce an Auger electron instead of an X-ray if an electron is missing from one of the low-lying electron shells. (The first process can even precipitate the second one.) Like IC electrons, Auger electrons have a discrete energy, resulting in a sharp energy peak in the spectrum.

Electron capture also involves an inner shell electron, which in this case is retained in the nucleus (changing the atomic number) and leaving the atom (not nucleus) in an excited state. The atom missing an inner electron can relax by a cascade of X-ray emissions as higher energy electrons in the atom fall to fill the vacancy left in the electron cloud by the captured electron. Such atoms also typically exhibit Auger electron emission. Electron capture, like beta decay, also typically results in excited atomic nuclei, which may then relax to a state of lowest nuclear energy by any of the methods permitted by spin constraints, including gamma decay and internal conversion decay.

title: Internal conversion