University of Virginia
The University of Virginia is a public research university in Charlottesville, Virginia. It was founded in 1819 by Declaration of former President Thomas Jefferson. UVA is a World Heritage site of the United States, it is known for its historic foundations, student-run honor code, secret societies. The original governing Board of Visitors included Jefferson, James Madison, James Monroe. Monroe was the sitting President of the United States at the time of its foundation and earlier Presidents Jefferson and Madison were UVA's first two rectors. Jefferson designed the original courses of study and Academical Village; as the first elected member to the research-driven Association of American Universities in the American South, since 1904, it remains the only AAU member in Virginia. The university is classified as a Research University with Very High Research by the Carnegie Foundation, its recent research efforts have been recognized by such scientific media as the journal Science, which credited UVA faculty with two of the top ten global breakthroughs of 2015.
UVA faculty and alumni have founded a large number of companies, such as Reddit. UVA offers 121 majors across three professional schools; the historic 1,682-acre campus is internationally protected by UNESCO and has been ranked as one of the most beautiful collegiate grounds in the country. UVA additionally maintains 2,913 acres southeast of the city, at Morven Farm; the university manages the College at Wise in Southwest Virginia, until 1972 operated George Mason University and the University of Mary Washington in Northern Virginia. Virginia student athletes compete in 27 collegiate sports and the Cavaliers lead the Atlantic Coast Conference in men's team NCAA championships with 18, additionally placing second in women's national titles with seven. UVA was awarded the men's Capital One Cup in 2015 after fielding the top overall men's athletics program in the nation. In 1802, while serving as President of the United States, Thomas Jefferson wrote to artist Charles Willson Peale that his concept of the new university would be "on the most extensive and liberal scale that our circumstances would call for and our faculties meet," and that it might attract talented students from "other states to come, drink of the cup of knowledge".
Virginia was home to the College of William and Mary, but Jefferson lost all confidence in his alma mater because of its religious nature – it required all its students to recite a catechism – and its stifling of the sciences. Jefferson had flourished under William and Mary professors William Small and George Wythe decades earlier, but the college was in a period of great decline and his concern became so dire by 1800 that he expressed to British chemist Joseph Priestley, "we have in that State, a college just well enough endowed to draw out the miserable existence to which a miserable constitution has doomed it." These words would ring true some seventy years when William and Mary fell bankrupt after the Civil War and the Williamsburg college was shuttered in 1881 being revived in a limited capacity as a small college for teachers until well into the twentieth century. In 1817, three Presidents and Chief Justice of the United States Supreme Court John Marshall joined 24 other dignitaries at a meeting held in the Mountain Top Tavern at Rockfish Gap.
After some deliberation, they selected nearby Charlottesville as the site of the new University of Virginia. Farmland just outside Charlottesville was purchased from James Monroe by the Board of Visitors as Central College; the school laid its first building's cornerstone late in that same year, the Commonwealth of Virginia chartered the new university on January 25, 1819. John Hartwell Cocke collaborated with James Madison and Joseph Carrington Cabell to fulfill Jefferson's dream to establish the university. Cocke and Jefferson were appointed to the building committee to supervise the construction. Like many of its peers, the university owned slaves, they served students and professors. The university's first classes met on March 7, 1825. In contrast to other universities of the day, at which one could study in either medicine, law, or divinity, the first students at the University of Virginia could study in one or several of eight independent schools – medicine, mathematics, ancient languages, modern languages, natural philosophy, moral philosophy.
Another innovation of the new university was that higher education would be separated from religious doctrine. UVA had no divinity school, was established independently of any religious sect, the Grounds were planned and centered upon a library, the Rotunda, rather than a church, distinguishing it from peer universities still functioning as seminaries for one particular strain of Protestantism or another. Jefferson opined to philosopher Thomas Cooper that "a professorship of theology should have no place in our institution", never has there been one. There were two degrees awarded by the university: Graduate, to a student who had completed the courses of one school. Jefferson was intimately involved in the university to the end, hosting Sunday dinners at his Monticello home for faculty and students until his death. So taken with the import of what he viewed the university's foundations and potential to be, counting it amongst his greatest accomplishments, Jefferson insisted his grave mention only his status as author of the Declaration of Independence and Virginia Statute for Religious Fre
U.S. National Geodetic Survey
"United States Coast Survey" and "United States Coast and Geodetic Survey" redirect here. They are former scientific agencies of the United States government which should not be confused with the United States Coast Guard, a seagoing U. S. government law enforcement and safety agency, the modern Coast Survey, a U. S. government agency that makes nautical charts, or the United States Geological Survey, a U. S. government agency that studies earth science and makes topographical maps. The National Geodetic Survey the United States Survey of the Coast, United States Coast Survey, United States Coast and Geodetic Survey, is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication. Since its foundation in its present form in 1970, it has been part of the National Oceanic and Atmospheric Administration, of the United States Department of Commerce; the National Geodetic Survey's history and heritage are intertwined with those of other NOAA offices.
As the U. S. Coast Survey and U. S. Coast and Geodetic Survey, the agency operated a fleet of survey ships, from 1917 the Coast and Geodetic Survey was one of the uniformed services of the United States with its own corps of commissioned officers. Upon the creation of the Environmental Science Services Administration in 1965, the commissioned corps was separated from the Survey to become the Environmental Science Services Administration Corps. Upon the creation of NOAA in 1970, the ESSA Corps became the National Oceanic and Atmospheric Administration Commissioned Officer Corps. Thus, the National Geodetic Survey's ancestor organizations are the ancestors of today's NOAA Corps and Office of Coast Survey and are among the ancestors of today's NOAA fleet. In addition, today's National Institute of Standards and Technology, although long since separated from the Survey, got its start as the Survey's Office of Weights and Measures; the National Geodetic Survey is an office of NOAA's National Ocean Service.
Its core function is to maintain the National Spatial Reference System, "a consistent coordinate system that defines latitude, height, scale and orientation throughout the United States." NGS is responsible for defining the NSRS and its relationship with the International Terrestrial Reference Frame. The NSRS enables precise and accessible knowledge of where things are in the United States and its territories; the NSRS may be divided into its geometric and physical components. The official geodetic datum of the United States, NAD83 defines the geometric relationship between points within the United States in three-dimensional space; the datum may be accessed via NGS's network of survey marks or through the Continuously Operating Reference Station network of GPS reference antennas. NGS is responsible for computing the relationship between NAD83 and the ITRF; the physical components of the NSRS are reflected in its height system, defined by the vertical datum NAVD88. This datum is a network of orthometric heights obtained through spirit leveling.
Because of the close relationship between height and Earth's gravity field, NGS collects and curates terrestrial gravity measurements and develops regional models of the geoid and its slope, the deflection of the vertical. NGS is responsible for ensuring the accuracy of the NSRS over time as the North American plate rotates and deforms over time due to crustal strain, post-glacial rebound, elastic deformation of the crust, other geophysical phenomena. NGS will release new datums in 2022; the North American Terrestrial Reference Frame of 2022 will supersede NAD83 in defining the geometric relationship between the North American plate and the ITRF. United States territories on the Pacific and Mariana plates will have their own respective geodetic datums; the North American-Pacific Geopotential Datum of 2022 will separately define the height system of the United States and its territories, replacing NAVD88. It will use a geoid model accurate to 1 centimeter to relate orthometric height to ellipsoidal height measured by GPS, eliminating the need for future leveling projects.
This geoid model will be based on airborne and terrestrial gravity measurements collected by NGS's GRAV-D program as well as satellite-based gravity models derived from observations collected by GRACE, GOCE, satellite altimetry missions. NGS provides a number of other public services, it maps changing shorelines in the United States and provides aerial imagery of regions affected by natural disasters, enabling rapid damage assessment by emergency managers and members of the public. The Online Positioning and User Service processes user-input GPS data and outputs position solutions within the NSRS; the agency offers other tools for conversion between datums. The original predecessor agency of the National Geodetic Survey was the United States Survey of the Coast, created within the United States Department of the Treasury by an Act of Congress on February 10, 1807, to conduct a "Survey of the Coast." The Survey of the Coast, the United States government's first scientific agency, represented the interest of the administration of President Thomas Jefferson in science and the stimulation of international trade by using scientific surveying methods to chart t
Grandfather Mountain is a mountain, a non-profit attraction, a North Carolina state park near Linville, North Carolina. At 5,946 feet, it is the highest peak on the eastern escarpment of the Blue Ridge Mountains, one of the major chains of the Appalachian Mountains; the Blue Ridge Parkway passes by the south side of the mountain and passes over the nearby Grandmother Gap. It is located at the meeting point of Avery and Watauga counties; until 2008, Grandfather Mountain was owned and operated as a nature preserve and tourist attraction. It was and still is best known for its mile-high swinging bridge, the highest in America, built in 1952 by Hugh Morton; the bridge links two of the mountain's rocky peaks, is known as the "swinging" bridge due to its tendency to sway in high winds. Morton developed the tourist attractions, he died on June 1, 2006 at the age of 85. After Morton's death, he donated all of his photographs, including many of Grandfather Mountain, Mildred the Bear, many other aspects of life on the Mountain to the University of North Carolina at Chapel Hill.
On September 29, 2008, North Carolina Governor Mike Easley announced that the state had agreed to purchase 2,600 acres of the undeveloped portions of Grandfather Mountain from the Morton family for $12 million. The area has been added to the North Carolina State Park system, becoming the 34th North Carolina state park; the Morton family established the Grandfather Mountain Stewardship Foundation to continue to operate the travel destination as an educational nature park. Grandfather Mountain State Park was established in 2009; the "backcountry" portion of the mountain that comprises the state park is now patrolled by state park rangers and other state law enforcement personnel. As part of the purchase agreement, the state acquired part of the mountain referred to as the "backcountry" in fee simple, it acquired a conservation easement and right of first refusal over the remaining "attraction side" of the mountain. In addition, the Morton family agreed to form a new non-profit organization and transfer ownership of the attraction to it.
This arrangement was made as an alternative to the state acquiring the entire mountain, because some of the traditional activities at Grandfather Mountain conflict with state park management policies. On September 18, 2011, the park had a grand opening celebration for its first office area, 3 miles from the Profile Trail-head on NC 105; the Grandfather Mountain Stewardship Foundation is the 501 nonprofit organization established by the Morton family in 2009 to operate the scenic travel attraction Grandfather Mountain in Linville, N. C; the Foundation manages the 720-acre property that includes the Mile High Swinging Bridge, Nature Museum and Animal Habitats. All proceeds from sales of tickets and souvenirs go toward preserving Grandfather Mountain and sharing its wonders in ways that deepen visitors' appreciation of nature and inspire good stewardship of the Earth; the mission statement of the Grandfather Mountain Stewardship Foundation, adopted in 2014, is: "Inspiring conservation of the natural world by helping guests explore and value the wonders of Grandfather Mountain."The Stewardship Foundation is managed by a seven-member Board of Directors, which in turn employs the leadership and staff of the Grandfather Mountain attraction.
Grandfather Mountain rises 5,946 feet above sea level, due to the considerable elevation gain the mountain boasts 16 distinct ecological communities. The mountain is famous for its rugged character, is home to many hidden caves and significant cliffs, it has been reported that Grandfather Mountain has experienced some of the "highest surface wind speeds recorded," with unverified speeds in excess of 200 mph. More Grandfather Mountain has upgraded their wind equipment in order to help resolve controversy over these high wind recordings. Notably however, the new equipment is located on the Swinging Bridge of the attraction; the new instruments may not record the highest wind speeds on the mountain, which extends another 684 vertical feet above the current location of the equipment. The primary massif of the mountain is oriented north to south, features four named peaks: Calloway Peak, Attic Window Peak, MacRae Peak, Linville Peak. Although not as high as the adjacent Calloway and Attic Window Peaks, MacRae is much more difficult to reach due to difficult and exposed approaches from both the north and south.
Two rivers have headwaters on Grandfather Mountain, the Linville River, flowing east, the Watauga River, flowing west. Many lesser streams originate on the slopes of Grandfather, including: Upper Boone Fork, Little Wilson Creek, Wilson Creek, Stack Rock Creek, others. On top of Grandfather Mountain, like many mountain peaks above 5000' in North Carolina, grows an "island" of Southern Appalachian spruce-fir forest. Though the forest was devastated during the 20th century by the introduction of the non-native balsam wooly adelgid, a remnant of this biome still exists on Grandfather Mountain. Many of these fir trees have been permanently bent by the high winds that prevail from the west. In addition to fir trees, these "mountaintop island" biomes are a valuable and threatened habitat for many other flora and fauna suited to survival at higher elevation; the attraction side of the mountain, which includes the Mile High Swinging Bridge, is accessed via Grandfather Mountain Entrance Road. Admittance fees are charged at the main gate.
Part or all of the attraction is sometimes closed du
Black Mountains (North Carolina)
The Black Mountains are a mountain range in western North Carolina, in the southeastern United States. They are part of the Blue Ridge Province of the Southern Appalachian Mountains; the Blacks are the highest mountains in the Eastern United States. The range takes its name from the dark appearance of the red spruce and Fraser fir trees that form a spruce-fir forest on the upper slopes which contrasts with the brown or lighter green appearance of the deciduous trees at lower elevations; the Eastern Continental Divide, which runs along the eastern Blue Ridge crest, intersects the southern tip of the Black Mountain range. The Black Mountains are home to Mount Mitchell State Park, which protects the range's highest summit and adjacent summits in the north-central section of the range. Much of the range is protected by the Pisgah National Forest; the Blue Ridge Parkway passes along the range's southern section, is connected to the summit of Mount Mitchell by North Carolina Highway 128. The Black Mountains are located in Yancey County, although the range's southern and western extremes are part of Buncombe County.
The Black Mountains form a J-shaped semicircle. The Blacks rise southward from the Little Crabtree Creek Valley in the north to the steep 6,327-foot summit of Celo Knob. A few miles south of Celo, the crest drops to 5,700 feet at Deep Gap before rising steeply again to the summit of Potato Hill in the north-central section of the range; the crest continues southward across the north-central section, which contains 6 of the 10 highest summits in the eastern United States, including the highest, Mount Mitchell, the second-highest, Mount Craig. South of Mount Mitchell, the crest drops to just under 6,000 feet at Stepp's Gap before rising again to 6,520 feet at the summit of Mount Gibbes. On the slopes of Potato Knob, just south of Clingmans Peak, the Black Mountain crest bends northwestward across Blackstock Knob before dropping again to 5,320 feet at Balsam Gap, where it intersects the Great Craggy Mountains to the southwest; the crest turns northward across Point Misery and Big Butt before descending to the Cane River Valley.
The northern section of the Black Mountains are drained by the Cane River to the west and the South Toe River to the east, both of which are part of the upper Nolichucky River watershed. The southwestern part of the range is drained by the upper French Broad River which, like the Nolichucky, is west of the Eastern Continental Divide and thus its waters wind up in the Gulf of Mexico. A few of the streams in the southeastern section of the range are part of the Catawba River watershed, are thus east of the Eastern Continental Divide. While the crest of the Black Mountain range is just 15 miles long, within these fifteen miles are 18 peaks climbing to at least 6300 feet above sea level; the Black Mountains rise prominently above the surrounding lower terrain. This is noticeable from the range's eastern side, which rises over 4500 feet above the Catawba River Valley and Interstate 40, providing some impressive mountain scenery; the Black Mountains consist of Precambrian gneiss and schists formed over a billion years ago from primordial sea sediments.
The mountains themselves were formed 200-400 million years ago during the Alleghenian orogeny, when the collision of two continental plates thrust what is now the Appalachian Mountains upward to form a large plateau. Weathering and minor geologic events in subsequent periods carved out the mountains. During the last Ice Age 20,000-16,000 years ago, glaciers did not advance into Southern Appalachia, but the change in temperatures drastically changed the forests in the region. A tree-less tundra existed in the Black Mountains and surrounding mountains in elevations above 3,500 feet. Spruce-fir forests dominated the lower elevations during this period, while hardwoods "fled" to warmer refuges in the coastal plains; as the ice sheets began retreating 16,000 years ago and temperatures started to rise, the hardwoods returned to the river valleys and lower slopes, the spruce-fir forest retreated to the higher elevations. Today, the spruce-fir forest atop the Black Mountains is one of ten or so spruce-fir "islands" remaining in the mountains of Southern Appalachia.
The forests of the Black Mountains are divided into three zones based on altitude: the spruce-fir forest, the northern hardwoods, the Appalachian hardwoods. The southern Appalachian spruce-fir forest, though sometimes referred to as "boreal" or "Canadian," is a unique plant community endemic to a few high peaks of the Southern Appalachians. In fact, it is more akin to a high elevation cloud forest, it is dominated by red spruce and Fraser fir, coats the elevations above 5,500 feet. The northern hardwoods, which consist of beech, yellow birch, buckeye, thrive between 4,500 feet and 5,500 feet; the more diverse Appalachian hardwoods, which include yellow poplar and various species of hickory and maple, dominate the slopes and stream valleys below 3,000 feet. Pine forests, consisting chiefly of Table Mountain pine, pitch pine, Virginia pine, are found on the drier south-facing slopes. Mountain paper birch, rare in North Carolina, grows sporadically on the slopes of Mount Mitchell. Wildlife in the Black Mountains is typical of the Appalachian highlands.
Mammals include black bears, white-tailed deer, river otters, minks and the endangered northern flying squirrel. Bird species include the wild turkey, the northern saw-whet owl, the pileated woodpecker, although peregrine fal
Rhyolite is an igneous, volcanic rock, of felsic composition. It may have any texture from glassy to aphanitic to porphyritic; the mineral assemblage is quartz and plagioclase. Biotite and hornblende are common accessory minerals, it is the extrusive equivalent to granite. Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock, outcrops of rhyolite may bear a resemblance to granite. Due to their high content of silica and low iron and magnesium contents, rhyolitic magmas form viscous lavas, they occur as breccias or in volcanic plugs and dikes. Rhyolites that cool too to grow crystals form a natural glass or vitrophyre called obsidian. Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic and lithophysal structures; some rhyolite is vesicular pumice. Many eruptions of rhyolite are explosive and the deposits may consist of fallout tephra/tuff or of ignimbrites. Eruptions of rhyolite are rare compared to eruptions of less felsic lavas.
Only three eruptions of rhyolite have been recorded since the start of the 20th century: at the St. Andrew Strait volcano in Papua New Guinea, Novarupta volcano in Alaska, Chaiten in southern Chile. Rhyolite has been found on islands far from land. Etsch Valley Vulcanite Group near Bolzano and the surrounding area Gréixer rhyolitic complex at Moixeró range Vosges Iceland: all active and extinct central volcanoes, e.g. Torfajökull, Leirhnjúkur / Krafla, Breiddalur central volcano Papa Stour in Shetland Copper Coast Geopark in southeast Ireland various locations around Snowdonia, Wales Massif de l'Esterel, France the Thuringian Forest consists of rhyolites and pyroclastic rocks of the Rotliegendes Saxony the north west Saxony-Anhalt north of Halle Saar-Nahe Basin e.g. the Königstuhl on the Donnersberg mountain Black Forest e.g. on the Karlsruher Grat Odenwald Andes Cascade Range Cobalt, Ontario Sheep Creek, Idaho Rocky Mountains Jemez Mountains Rhyolite, Nevada was named after a rhyolite deposit that characterised the area.
Wichita Mountains within the Southern Oklahoma Aulacogen St. Francois Mountains Mount Jasper, New Hampshire Yellowstone Crater Lake, Oregon Palisade Head, a formation found at Tettegouche State Park, Minnesota; the Taupo Volcanic Zone in New Zealand has a large concentration of young rhyolite volcanoes Glass House Mountains National Park, Australia the Gondwana Rainforests of Australia World Heritage Area contains rhyolite-restricted flora along the Great Dividing Range the Flinders Peak Group in the Teviot Range in the Fassifern Valley is a rhyolite of varying colours. The Malani Igneous Suite, India; the Yandang Shan mountain chain, near the town of Wenzhou, Zhejiang province, China Tambora, Indonesia Mount Kilimanjaro, Kenya/Tanzania The name rhyolite was introduced into geology in 1860 by the German traveler and geologist Ferdinand von Richthofen from the Greek word rhýax and the rock name suffix "-lite". In North American pre-historic times, rhyolite was quarried extensively in eastern Pennsylvania in the United States.
Among the leading quarries was the Carbaugh Run Rhyolite Quarry Site in Adams County. Rhyolite was mined there starting 11,500 years ago. Tons of rhyolite were traded across the Delmarva Peninsula, because the rhyolite kept a sharp point when knapped and was used to make spear points and arrowheads. Comendite – A hard, peralkaline igneous rock, a type of light blue grey rhyolite List of rock types – A list of rock types recognized by geologists Pantellerite – A peralkaline rhyolite type of volcanic rock Thunderegg – A nodule-like rock, formed within rhyolitic volcanic ash layers University of North Dakota description of rhyolite Information from rocks-rock.com
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are sometimes described as lava; the molten rock is formed in the interior of some planets, including Earth, some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption; when it has stopped moving, lava solidifies to form igneous rock. The term lava flow is shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows; the word lava comes from Italian, is derived from the Latin word labes which means a fall or slide.
The first use in connection with extruded magma was in a short account written by Francesco Serao on the eruption of Vesuvius in 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain; the composition of all lava of the Earth's crust is dominated by silicate minerals feldspars, pyroxenes, amphiboles and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: felsic and mafic; these classes are chemical, the chemistry of lava tends to correlate with the magma temperature, its viscosity and its mode of eruption. Felsic or silicic lavas such as rhyolite and dacite form lava spines, lava domes or "coulees" and are associated with pyroclastic deposits. Most silicic lava flows are viscous, fragment as they extrude, producing blocky autobreccias; the high viscosity and strength are the result of their chemistry, high in silica, potassium and calcium, forming a polymerized liquid rich in feldspar and quartz, thus has a higher viscosity than other magma types.
Felsic magmas can erupt at temperatures as low as 650 to 750 °C. Unusually hot rhyolite lavas, may flow for distances of many tens of kilometres, such as in the Snake River Plain of the northwestern United States. Intermediate or andesitic lavas are lower in aluminium and silica, somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, commonly hotter, they tend to be less viscous. Greater temperatures tend to destroy polymerized bonds within the magma, promoting more fluid behaviour and a greater tendency to form phenocrysts. Higher iron and magnesium tends to manifest as a darker groundmass, occasionally amphibole or pyroxene phenocrysts. Mafic or basaltic lavas are typified by their high ferromagnesian content, erupt at temperatures in excess of 950 °C. Basaltic magma is high in iron and magnesium, has lower aluminium and silica, which taken together reduces the degree of polymerization within the melt.
Owing to the higher temperatures, viscosities can be low, although still thousands of times higher than water. The low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent; the thickness of a basalt lava on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of pāhoehoe types, rather than block lavas. Underwater, they can form pillow lavas, which are rather similar to entrail-type pahoehoe lavas on land. Ultramafic lavas such as komatiite and magnesian magmas that form boninite take the composition and temperatures of eruptions to the extreme. Komatiites contain over 18% magnesium oxide, are thought to have erupted at temperatures of 1,600 °C.
At this temperature there is no polymerization of the mineral compounds, creating a mobile liquid. Most if not all ultramafic lavas are no younger than the Proterozoic, with a few ultramafic magmas known from the Phanerozoic. No modern komatiite lavas are known, as the Earth's mantle has cooled too much to produce magnesian magmas; some lavas of unusual composition have erupted onto the surface of the Earth. These include: Carbonatite and natrocarbonatite lavas are known from Ol Doinyo Lengai volcano in Tanzania, the sole example of an active carbonatite volcano. Iron oxide lavas are thought to be the source of the iron ore at Kiruna, Sweden which formed during the Proterozoic. Iron oxide lavas of Pliocene age occur at the El Laco volcanic complex on the Chile-Argentina border. Iron oxide lavas are thought to be the result of immiscible separation of iron oxide magma from a parental magma of calc-alkaline or alkaline composition. Sulfur lava flows up to 250 metres 10 metres wide occur at Lastarria volcano, Chile.
They were formed by the melting of sulfur deposits at temperatures as low as 113 °C
Lewis Fork Wilderness
The Lewis Fork Wilderness is an area in the Mount Rogers National Recreation Area protected by the Eastern Wilderness Act of Congress to maintain its present, natural condition. As part of the wilderness system, it is intended to preserve a variety of natural life forms and contribute to a diversity of plant and animal gene pools. Over half of the ecosystems in the United States exist within designated wilderness; the highlight of the wilderness is Mount Rogers, which at 5729 feet is the tallest mountain in Virginia and the highest point in the Appalachians between North Carolina and New Hampshire. With frequent cloud cover and moist moss draping from rocks and tree limbs, the wooded area at the top of the mountain creates a sense of awe in a silence so quiet that a finger snap can produce an echo; the area is part of the Mount Rogers Cluster. The wilderness is on the southeast side of the Mount Rogers National Recreation Area, near the town of Konnarock in Grayson and Smyth Counties, it is bounded by Whitetop Road on the west, Laurel Valley Road on the north, Pine Mountain on the southeast.
The Appalachian Trail passes in an out of the wilderness for a total 5.5 miles in the wilderness. Trailheads are near Grayson Highlands State Park on the north. Other Trails in the area include: Cliffside Trail, FS 4533B, 1.4 miles, difficult, no blazes Grassy Branch Trail, FS 4535, 3.2 miles, moderate, no blazes Helton Creek Trail, FS 4538, 3.4 miles, moderate, no blazes Lewis Fork Triil, FS 4533, 5.5 miles, moderate/difficult, no blazes Mount Rogers Trail, FS 166, 4.1 miles, difficult, no blazes Old Orchard Trail, FS 4533A, 1.6 miles, moderate, no blazes Pine Mountain Trail, FS 4595, 2 miles, blue blazes Sugar Maple Trail, FS 4572, 2.3 miles, moderate, no blazes Habitats created by high elevations, extended slopes and streams support a large biological diversity. The wilderness and surrounding country are considered one of the most important centers for biological diversity in the eastern United States. Besides the oak-hickory forest common in eastern deciduous woodlands, a variety of forest communities include cove forests in rich, moist secluded areas.
Frazer firs on the summit of Mt. Rogers are beginning to decline because of infestation by the balsam woolly adelgid, an exotic insect pest. Streams in the area have been recognized for their high water quality. Wild natural trout streams in Virginia are classified by the Department of Game and Inland Fisheries by their water quality, with class i the highest and class iv the lowest. Lewis Fork is a class i stream and Charlies Branch, Daves Branch, Grindstone Branch and Helton Creek are class ii streams. Grayson Highlands State Park, adjacent to the wilderness, contains balds, large open grassy areas at a high elevation with good views in many directions. Ponies have been allowed to run wild while grazing the balds. Mount Rogers is a roundish knob with multiple ridges radiating in all directions. Wilburn Ridge, Cabin Ridge and Briar Ridge are on the south side of Pine Mountain, Elk Ridge is on the north side of Pine Mountain, Elk Garden Ridge is on the west. Big Laurel Creek, the drainage on the west slope of Elk Ridge, is part of the Holston River watershed.
The wilderness, in the Southern Blue Ridge Mountains Subsection within the Central Appalachian Broadleaf Coniferous Forest-Meadow Province, has elevations ranging from 3400 feet near Big Laurel Creek to 5700 feet on Mt Rogers. A tectonic uplift of the mountains created. Designated by Congress in 1984, the wilderness now has a total of 6076 acres, is managed by the Forest Service through the Mount Rogers National Recreation Area. There are some regulations to maintain the integrity of the area as a wilderness. For example, motorized equipment, motor vehicles and mountain bikes are prohibited, group size is limited to ten people, limits are placed on camping. Devil's Den-Ewing Mountain Horse Heaven Little Dry Run Wilderness Addition Shaw Gap Feathercamp Mount Rogers Crest Zone Whitetop Mountain Whitetop Laurel Rogers Ridge London Bridge Branch Beaverdam Creek