Cirque
A cirque is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are cwm. A cirque may be a shaped landform arising from fluvial erosion; the concave shape of a glacial cirque is open on the downhill side, while the cupped section is steep. Cliff-like slopes, down which ice and glaciated debris combine and converge, form the three or more higher sides; the floor of the cirque ends up bowl-shaped as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens: hence it experiences somewhat greater erosion forces, is most overdeepened below the level of the cirque's low-side outlet and its down slope valley. If the cirque is subject to seasonal melting, the floor of the cirque most forms a tarn behind a dam which marks the downstream limit of the glacial overdeepening: the dam itself can be composed of moraine, glacial till, or a lip of the underlying bedrock; the fluvial cirque or makhtesh, found in karst landscapes, is formed by intermittent river flow cutting through layers of limestone and chalk leaving sheer cliffs.
A common feature for all fluvial-erosion cirques is a terrain which includes erosion resistant upper structures overlying materials which are more eroded. Glacial cirques are found amongst mountain ranges throughout the world. Situated high on a mountainside near the firn line, they are partially surrounded on three sides by steep cliffs; the highest cliff is called a headwall. The fourth side forms the lip, threshold or sill, the side at which the glacier flowed away from the cirque. Many glacial cirques contain tarns dammed by a bedrock threshold; when enough snow accumulates it can flow out the opening of the bowl and form valley glaciers which may be several kilometers long. Cirques form in conditions; these areas are sheltered from heat. The process of nivation follows, whereby a hollow in a slope may be enlarged by ice segregation weathering and glacial erosion. Ice segregation erodes the rock vertical rock face and causes it to disintegrate, which may result in an avalanche bringing down more snow and rock to add to the growing glacier.
This hollow may become large enough that glacial erosion intensifies. The enlarging of this open ended concavity creates a larger leeward deposition zone, furthering the process of glaciation. Debris in the ice may abrade the bed surface; the hollow may become a large bowl shape in the side of the mountain, with the headwall being weathered by ice segregation, as well as being eroded by plucking. The basin will become deeper as it continues to be eroded by ice abrasion. Should ice segregation and abrasion continue, the dimensions of the cirque will increase, but the proportion of the landform would remain the same. A bergschrund forms when the movement of the glacier separates the moving ice from the stationary ice forming a crevasse; the method of erosion of the headwall lying between the surface of the glacier and the cirque’s floor has been attributed to freeze-thaw mechanisms. The temperature within the bergschrund changes little, studies have shown that ice segregation may happen with only small changes in temperature.
Water that flows into the bergschrund can be cooled to freezing temperatures by the surrounding ice allowing freeze-thaw mechanisms to occur. If two adjacent cirques erode toward one another, an arête, or steep sided ridge, forms; when three or more cirques erode toward one another, a pyramidal peak is created. In some cases, this peak will be made accessible by one or more arêtes; the Matterhorn in the European Alps is an example of such a peak. Where cirques form one behind the other, a cirque stairway results as at the Zastler Loch in the Black Forest; as glaciers can only originate above the snowline, studying the location of present-day cirques provides information on past glaciation patterns and on climate change. Although a less common usage, the term cirque is used for amphitheatre-shaped, fluvial-erosion features. For example, an 200 square kilometres anticlinal erosion cirque is at 30°35′N 34°45′E on the southern boundary of the Negev highlands; this erosional cirque or makhtesh was formed by intermittent river flow in the Makhtesh Ramon cutting through layers of limestone and chalk, resulting in cirque walls with a sheer 200 metres drop.
The Cirque du Bout du Monde is another such a feature, created in karst terraine in the Burgundy region of the department of Côte-d'Or in France. Yet another type of fluvial erosion formed cirque is found on Réunion island, which includes the tallest volcanic structure in the Indian Ocean; the island consists of an active shield-volcano and an extinct eroded volcano. Three cirques have eroded there in a sequence of agglomerated, fragmented rock and volcanic breccia associated with pillow-lavas overlain by more coherent, solid lavas. A common feature for all fluvial-erosion cirques is a terrain which includes erosion resistant
United States Forest Service
The United States Forest Service is an agency of the U. S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands, which encompass 193 million acres. Major divisions of the agency include the National Forest System and Private Forestry, Business Operations, the Research and Development branch. Managing 25% of federal lands, it is the only major national land agency, outside the U. S. Department of the Interior; the concept of the National Forests was born from Theodore Roosevelt’s conservation group and Crockett Club, due to concerns regarding Yellowstone National Park beginning as early as 1875. In 1876, Congress formed the office of Special Agent in the Department of Agriculture to assess the quality and conditions of forests in the United States. Franklin B. Hough was appointed the head of the office. In 1881, the office was expanded into the newly formed Division of Forestry; the Forest Reserve Act of 1891 authorized withdrawing land from the public domain as "forest reserves," managed by the Department of the Interior.
In 1901, the Division of Forestry was renamed the Bureau of Forestry. The Transfer Act of 1905 transferred the management of forest reserves from the General Land Office of the Interior Department to the Bureau of Forestry, henceforth known as the United States Forest Service. Gifford Pinchot was the first United States Chief Forester in the Presidency of Theodore Roosevelt. Significant federal legislation affecting the Forest Service includes the Weeks Act of 1911, the Multiple Use – Sustained Yield Act of 1960, P. L. 86-517. L. 88-577. L. 94-588. L. 91-190. L. 95-313. L. 95-307. In February 2009, the Government Accountability Office evaluated whether the Forest Service should be moved from the Department of Agriculture to the Department of the Interior, which includes the National Park Service, the Fish and Wildlife Service, the Bureau of Land Management, managing some 438,000,000 acres of public land; as of 2009, the Forest Service has a total budget authority of $5.5 billion, of which 42% is spent fighting fires.
The Forest Service employs 34,250 employees in 750 locations, including 10,050 firefighters, 737 law enforcement personnel, 500 scientists. The mission of the Forest Service is "To sustain the health and productivity of the Nation's forests and grasslands to meet the needs of present and future generations." Its motto is "Caring for the land and serving people." As the lead federal agency in natural resource conservation, the US Forest Service provides leadership in the protection and use of the nation's forest and aquatic ecosystems. The agency's ecosystem approach to management integrates ecological and social factors to maintain and enhance the quality of the environment to meet current and future needs. Through implementation of land and resource management plans, the agency ensures sustainable ecosystems by restoring and maintaining species diversity and ecological productivity that helps provide recreation, timber, fish, wildlife and aesthetic values for current and future generations of people.
The everyday work of the Forest Service balances resource extraction, resource protection, providing recreation. The work includes managing 193,000,000 acres of national forest and grasslands, including 59,000,000 acres of roadless areas. Further, the Forest Service fought fires on 2,996,000 acres of land in 2007; the Forest Service organization includes ranger districts, national forests, research stations and research work units and the Northeastern Area Office for State and Private Forestry. Each level has responsibility for a variety of functions; the Chief of the Forest Service is a career federal employee. The Chief reports to the Under Secretary for Natural Resources and Environment in the U. S. Department of Agriculture, an appointee of the President confirmed by the Senate; the Chief's staff provides broad policy and direction for the agency, works with the Administration to develop a budget to submit to Congress, provides information to Congress on accomplishments, monitors activities of the agency.
There are five deputy chiefs for the following areas: National Forest System and Private Forestry and Development, Business Operations, Finance. The Forest Service Research and Development deputy area includes five research stations, the Forest Products Laboratory, the International Institute of Tropical Forestry, in Puerto Rico. Station directors, like regional foresters, report to the Chief. Research stations include Northern, Pacific Northwest, Pacific Southwest, Rocky Mountain, Southern. There are 92 research work units located at 67 sites throughout the United States. There are 80 Experimental Forests and Ranges that have been established progressively since 1908; the system provides places for long-term science and management studies in major vegetation types of the 195 million acres of public land administered by the Forest Service. Individual sites range from 47 to 22,500 ha in size. Operations of Experimental Forests and Ranges are directed by local research teams for the individual sites, by Research Stations for the regions in which they are located, at the level of the Forest Service.
Major themes in
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth from an ore body, vein, reef or placer deposit. These deposits form a mineralized package, of economic interest to the miner. Ores recovered by mining include metals, oil shale, limestone, dimension stone, rock salt, potash and clay. Mining is required to obtain any material that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or water. Mining of stones and metal has been a human activity since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, final reclamation of the land after the mine is closed. De Re Metallica, Georgius Agricola, 1550, Book I, Para. 1Mining operations create a negative environmental impact, both during the mining activity and after the mine has closed.
Hence, most of the world's nations have passed regulations to decrease the impact. Work safety has long been a concern as well, modern practices have improved safety in mines. Levels of metals recycling are low. Unless future end-of-life recycling rates are stepped up, some rare metals may become unavailable for use in a variety of consumer products. Due to the low recycling rates, some landfills now contain higher concentrations of metal than mines themselves. Since the beginning of civilization, people have used stone and metals found close to the Earth's surface; these were used to make early weapons. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries; the mines at Grimes Graves and Krzemionki are famous, like most other flint mines, are Neolithic in origin. Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District; the oldest-known mine on archaeological record is the Ngwenya Mine in Swaziland, which radiocarbon dating shows to be about 43,000 years old.
At this site Paleolithic humans mined hematite to make the red pigment ochre. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. Ancient Egyptians mined malachite at Maadi. At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were found at Wadi Hammamat, Tura and various other Nubian sites on the Sinai Peninsula and at Timna. Mining in Egypt occurred in the earliest dynasties; the gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by the Greek author Diodorus Siculus, who mentions fire-setting as one method used to break down the hard rock holding the gold. One of the complexes is shown in one of the earliest known maps.
The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust. Mining in Europe has a long history. Examples include the silver mines of Laurium. Although they had over 20,000 slaves working them, their technology was identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos, marble was quarried by the Parians after they arrived in the 7th century BC; the marble was shipped away and was found by archaeologists to have been used in buildings including the tomb of Amphipolis. Philip II of Macedon, the father of Alexander the Great, captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns, he captured gold mines in Thrace for minting coinage producing 26 tons per year. However, it was the Romans who developed large scale mining methods the use of large volumes of water brought to the minehead by numerous aqueducts; the water was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining, as well as washing comminuted, or crushed and driving simple machinery.
The Romans used hydraulic mining methods on a large scale to prospect for the veins of ore a now-obsolete form of mining known as hushing. They built numerous aqueducts to supply water to the minehead. There, the water stored in large tanks; when a full tank was opened, the flood of water sluiced away the overburden to expose the bedrock underneath and any gold veins. The rock was worked upon by fire-setting to heat the rock, which would be quenched with a stream of water; the resulting thermal shock cracked the rock, enabling it to be removed by further streams of water from the overhead tanks. The Roman miners used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines; the methods had been developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas, where seven long aqueducts tapped local rivers and sluiced the deposits. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited.
In Great Britain the natives had mined minerals for millennia, but after the Roman conquest, the scale of the operations increased as the Romans needed Britannia's resources gold, silver
Interstate 70
Interstate 70 is a major east–west Interstate Highway in the United States that runs from I-15 near Cove Fort, Utah, to I-695 near Baltimore, Maryland. I-70 traces the path of U. S. Route 40 east of the Rocky Mountains. West of the Rockies, the route of I-70 was derived from multiple sources; the Interstate runs through or near many major cities, including Denver, Kansas City, St. Louis, Columbus and Baltimore; the sections of the interstate in Missouri and Kansas have laid claim to be the first interstate in the United States. The Federal Highway Administration has claimed the section of I-70 through Glenwood Canyon, completed in 1992, was the last piece of the Interstate Highway system, as planned, to open to traffic; the construction of I-70 in Colorado and Utah is considered an engineering marvel, as the route passes through the Eisenhower Tunnel, Glenwood Canyon, the San Rafael Swell. The Eisenhower Tunnel is the highest point along the Interstate Highway system, with an elevation of 11,158 ft. Interstate 70 begins at an interchange with Interstate 15 near Cove Fort.
Heading east, I-70 crosses between the Tushar and Pahvant ranges via Clear Creek Canyon and descends into the Sevier Valley, where I-70 serves Richfield, the only town of more than a few hundred people along I-70's path in Utah. Upon leaving the valley near Salina, I-70 crosses the 7,923 ft Salina Summit and crosses a massive geologic formation called the San Rafael Swell. Prior to the construction of I-70, the swell was inaccessible via paved roads and undiscovered. Once this 108 mi section was opened to traffic in 1970, it became the longest stretch of interstate highway with no services and the first highway in the U. S. built over a new route since the Alaska Highway. It became the longest piece of interstate highway to be opened at one time. Although opened in 1970, this section was not formally complete until 1990, when a second steel arch bridge spanning Eagle Canyon was opened to traffic. Since I-70's construction, the swell has been noted for its desolate beauty; the swell has since been nominated for National Park or National Monument status on multiple occasions.
If the swell is granted this status, it arguably would be the first time a National Park owes its existence to an interstate highway. Most of the exits in this span are rest areas, brake check areas, runaway truck ramps with few traditional freeway exits. I-70 exits the swell near Green River. From Green River to the Colorado state line, I-70 follows the southern edge of the Book Cliffs. Entering from Utah, I-70 descends into the Grand Valley, where it meets the Colorado River, which provides its path up the western slope of the Rocky Mountains. Here I-70 serves the Grand Junction metro area before traversing more mountainous terrain; the last section of I-70 to be completed was the 15-mile Glenwood Canyon. This stretch was completed in 1992 and was an engineering marvel, due to the difficult terrain and narrow space in the canyon, which requires corners that are sharper than normal Interstate standards. Construction was delayed for many years due to environmental concerns; the difficulties in building the road in the canyon were compounded by the fact the Denver & Rio Grande Western railroad occupied the south bank, many temporary construction projects took place to keep US 6 open, at the time the only east–west road in the area.
Much of the highway is elevated above the Colorado River. The speed limit in this section is due to the limited sight distance and sharp corners; the Eisenhower–Johnson Memorial Tunnel, the highest vehicular tunnel in North America and the longest tunnel built under the Interstate program, passes through the Continental Divide. Because of the rugged and narrow terrain of the Rocky Mountains, I-70 is one of few roads connecting Colorado's ski resorts with Denver. Descending through the eastern foothills of the Rocky Mountains, one can see the Denver skyline on a clear day; this can fool truckers and other unsuspecting drivers, because one must still traverse 10 miles of steep grade road before reaching the city. A series of signs warns truckers of the steep grade; as I-70 leaves the foothills, it goes through Denver and intersects Interstate 25, serving as the central east-west artery through the city. Leaving Denver, I-70 levels out and traverses the wide plains through eastern Colorado. East of Denver, I-70 makes a broad turn to the south-southeast for 30 miles before reaching Limon and resuming its eastward journey toward Kansas.
Coming from Colorado, I-70 enters the prairie and rolling hills of Kansas. This portion of I-70 was the first segment to start being paved and to be completed in the Interstate Highway System, it is given the nickname "Main Street of Kansas", as the interstate extends from the western border to the eastern border of the state, covering 424 miles and passing through most of the state's principal cities in the process. In Salina, I-70 intersects with I-135, the longest "spur" route in the Interstate system, forming the latter's northern terminus. In Topeka, I-70 intersects I-470, twice. At the eastern intersection, the Kansas Turnpike merges, with I-70 becoming a toll road; this is one of only two sections of I-70. I-70 carries this designation from Topeka to the eastern terminus of the turnpike. About halfway between Topeka and Kansas City, Kansas, I-70 passes through Lawrence; the tolled portion of the turnpike ends near Bonner Springs, just west of Kansas City. There is a third child route in Topeka, I-335, which runs from I-470 south to meet up wit
Los Angeles
Los Angeles the City of Los Angeles and known by its initials L. A. is the most populous city in California, the second most populous city in the United States, after New York City, the third most populous city in North America. With an estimated population of four million, Los Angeles is the cultural and commercial center of Southern California; the city is known for its Mediterranean climate, ethnic diversity and the entertainment industry, its sprawling metropolis. Los Angeles is the largest city on the West Coast of North America. Los Angeles is in a large basin bounded by the Pacific Ocean on one side and by mountains as high as 10,000 feet on the other; the city proper, which covers about 469 square miles, is the seat of Los Angeles County, the most populated county in the country. Los Angeles is the principal city of the Los Angeles metropolitan area, the second largest in the United States after that of New York City, with a population of 13.1 million. It is part of the Los Angeles-Long Beach combined statistical area the nation's second most populous area with a 2015 estimated population of 18.7 million.
Los Angeles is one of the most substantial economic engines within the United States, with a diverse economy in a broad range of professional and cultural fields. Los Angeles is famous as the home of Hollywood, a major center of the world entertainment industry. A global city, it has been ranked 6th in the Global Cities Index and 9th in the Global Economic Power Index; the Los Angeles metropolitan area has a gross metropolitan product of $1.044 trillion, making it the third-largest in the world, after the Tokyo and New York metropolitan areas. Los Angeles hosted the 1932 and 1984 Summer Olympics and will host the event for a third time in 2028; the city hosted the Miss Universe pageant twice, in 1990 and 2006, was one of 9 American cities to host the 1994 FIFA men's soccer World Cup and one of 8 to host the 1999 FIFA women's soccer World Cup, hosting the final match for both tournaments. Home to the Chumash and Tongva, Los Angeles was claimed by Juan Rodríguez Cabrillo for Spain in 1542 along with the rest of what would become Alta California.
The city was founded on September 4, 1781, by Spanish governor Felipe de Neve. It became a part of Mexico in 1821 following the Mexican War of Independence. In 1848, at the end of the Mexican–American War, Los Angeles and the rest of California were purchased as part of the Treaty of Guadalupe Hidalgo, becoming part of the United States. Los Angeles was incorporated as a municipality on April 4, 1850, five months before California achieved statehood; the discovery of oil in the 1890s brought rapid growth to the city. The completion of the Los Angeles Aqueduct in 1913, delivering water from Eastern California assured the city's continued rapid growth; the Los Angeles coastal area was settled by the Chumash tribes. A Gabrieleño settlement in the area was called iyáangẚ, meaning "poison oak place". Maritime explorer Juan Rodríguez Cabrillo claimed the area of southern California for the Spanish Empire in 1542 while on an official military exploring expedition moving north along the Pacific coast from earlier colonizing bases of New Spain in Central and South America.
Gaspar de Portolà and Franciscan missionary Juan Crespí, reached the present site of Los Angeles on August 2, 1769. In 1771, Franciscan friar Junípero Serra directed the building of the Mission San Gabriel Arcángel, the first mission in the area. On September 4, 1781, a group of forty-four settlers known as "Los Pobladores" founded the pueblo they called El Pueblo de Nuestra Señora la Reina de los Ángeles,'The Town of Our Lady the Queen of the Angels'; the present-day city has the largest Roman Catholic Archdiocese in the United States. Two-thirds of the Mexican or settlers were mestizo or mulatto, a mixture of African and European ancestry; the settlement remained a small ranch town for decades, but by 1820, the population had increased to about 650 residents. Today, the pueblo is commemorated in the historic district of Los Angeles Pueblo Plaza and Olvera Street, the oldest part of Los Angeles. New Spain achieved its independence from the Spanish Empire in 1821, the pueblo continued as a part of Mexico.
During Mexican rule, Governor Pío Pico made Los Angeles Alta California's regional capital. Mexican rule ended during the Mexican–American War: Americans took control from the Californios after a series of battles, culminating with the signing of the Treaty of Cahuenga on January 13, 1847. Railroads arrived with the completion of the transcontinental Southern Pacific line to Los Angeles in 1876 and the Santa Fe Railroad in 1885. Petroleum was discovered in the city and surrounding area in 1892, by 1923, the discoveries had helped California become the country's largest oil producer, accounting for about one-quarter of the world's petroleum output. By 1900, the population had grown to more than 102,000; the completion of the Los Angeles Aqueduct in 1913, under the supervision of William Mulholland, assured the continued growth of the city. Due to clauses in the city's charter that prevented the City of Los Angeles from selling or providing water from the aqueduct to any area outside its borders, many adjacent city and communities became compelled to annex themselves into Los Angeles.
Los Angeles created the first municipal zoning ordinance in the United States. On September 14, 1908, the Los Angeles City Council promulgated residential and industrial land use zones; the new ordinance established three residential zones of a single type, where industrial uses were
United States
The United States of America known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U. S. is the third most populous country. The capital is Washington, D. C. and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico; the State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean; the U. S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The diverse geography and wildlife of the United States make it one of the world's 17 megadiverse countries.
Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago. European colonization began in the 16th century; the United States emerged from the thirteen British colonies established along the East Coast. Numerous disputes between Great Britain and the colonies following the French and Indian War led to the American Revolution, which began in 1775, the subsequent Declaration of Independence in 1776; the war ended in 1783 with the United States becoming the first country to gain independence from a European power. The current constitution was adopted in 1788, with the first ten amendments, collectively named the Bill of Rights, being ratified in 1791 to guarantee many fundamental civil liberties; the United States embarked on a vigorous expansion across North America throughout the 19th century, acquiring new territories, displacing Native American tribes, admitting new states until it spanned the continent by 1848. During the second half of the 19th century, the Civil War led to the abolition of slavery.
By the end of the century, the United States had extended into the Pacific Ocean, its economy, driven in large part by the Industrial Revolution, began to soar. The Spanish–American War and World War I confirmed the country's status as a global military power; the United States emerged from World War II as a global superpower, the first country to develop nuclear weapons, the only country to use them in warfare, a permanent member of the United Nations Security Council. Sweeping civil rights legislation, notably the Civil Rights Act of 1964, the Voting Rights Act of 1965 and the Fair Housing Act of 1968, outlawed discrimination based on race or color. During the Cold War, the United States and the Soviet Union competed in the Space Race, culminating with the 1969 U. S. Moon landing; the end of the Cold War and the collapse of the Soviet Union in 1991 left the United States as the world's sole superpower. The United States is the world's oldest surviving federation, it is a representative democracy.
The United States is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, other international organizations. The United States is a developed country, with the world's largest economy by nominal GDP and second-largest economy by PPP, accounting for a quarter of global GDP; the U. S. economy is post-industrial, characterized by the dominance of services and knowledge-based activities, although the manufacturing sector remains the second-largest in the world. The United States is the world's largest importer and the second largest exporter of goods, by value. Although its population is only 4.3% of the world total, the U. S. holds 31% of the total wealth in the world, the largest share of global wealth concentrated in a single country. Despite wide income and wealth disparities, the United States continues to rank high in measures of socioeconomic performance, including average wage, human development, per capita GDP, worker productivity.
The United States is the foremost military power in the world, making up a third of global military spending, is a leading political and scientific force internationally. In 1507, the German cartographer Martin Waldseemüller produced a world map on which he named the lands of the Western Hemisphere America in honor of the Italian explorer and cartographer Amerigo Vespucci; the first documentary evidence of the phrase "United States of America" is from a letter dated January 2, 1776, written by Stephen Moylan, Esq. to George Washington's aide-de-camp and Muster-Master General of the Continental Army, Lt. Col. Joseph Reed. Moylan expressed his wish to go "with full and ample powers from the United States of America to Spain" to seek assistance in the revolutionary war effort; the first known publication of the phrase "United States of America" was in an anonymous essay in The Virginia Gazette newspaper in Williamsburg, Virginia, on April 6, 1776. The second draft of the Articles of Confederation, prepared by John Dickinson and completed by June 17, 1776, at the latest, declared "The name of this Confederation shall be the'United States of America'".
The final version of the Articles sent to the states for ratification in late 1777 contains the sentence "The Stile of this Confederacy shall be'The United States of America'". In June 1776, Thomas Jefferson wrote the phrase "UNITED STATES OF AMERICA" in all capitalized letters in the headline of his "original Rough draught" of the Declaration of Independence; this draft of the document did not surface unti
Mountain range
A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form and alignment that have arisen from the same cause an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are found on many planetary mass objects in the Solar System and are a feature of most terrestrial planets. Mountain ranges are segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not have the same geologic structure or petrology, they may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, volcanic landforms resulting in a variety of rock types. Most geologically young mountain ranges on the Earth's land surface are associated with either the Pacific Ring of Fire or the Alpide Belt.
The Pacific Ring of Fire includes the Andes of South America, extends through the North American Cordillera along the Pacific Coast, the Aleutian Range, on through Kamchatka, Taiwan, the Philippines, Papua New Guinea, to New Zealand. The Andes is 7,000 kilometres long and is considered the world's longest mountain system; the Alpide belt includes Indonesia and Southeast Asia, through the Himalaya, Caucasus Mountains, Balkan Mountains fold mountain range, the Alps, ends in the Spanish mountains and the Atlas Mountains. The belt includes other European and Asian mountain ranges; the Himalayas contain the highest mountains in the world, including Mount Everest, 8,848 metres high and traverses the border between China and Nepal. Mountain ranges outside these two systems include the Arctic Cordillera, the Urals, the Appalachians, the Scandinavian Mountains, the Great Dividing Range, the Altai Mountains and the Hijaz Mountains. If the definition of a mountain range is stretched to include underwater mountains the Ocean Ridges form the longest continuous mountain system on Earth, with a length of 65,000 kilometres.
The mountain systems of the earth are characterized by a tree structure, where mountain ranges can contain sub-ranges. The sub-range relationship is expressed as a parent-child relationship. For example, the White Mountains of New Hampshire and the Blue Ridge Mountains are sub-ranges of the Appalachian Mountains. Equivalently, the Appalachians are the parent of the White Mountains and Blue Ridge Mountains, the White Mountains and the Blue Ridge Mountains are children of the Appalachians; the parent-child expression extends to the sub-ranges themselves: the Sandwich Range and the Presidential Range are children of the White Mountains, while the Presidential Range is parent to the Northern Presidential Range and Southern Presidential Range. The position of mountains influences climate, such as snow; when air masses move up and over mountains, the air cools producing orographic precipitation. As the air descends on the leeward side, it warms again and is drier, having been stripped of much of its moisture.
A rain shadow will affect the leeward side of a range. Mountain ranges are subjected to erosional forces which work to tear them down; the basins adjacent to an eroding mountain range are filled with sediments which are buried and turned into sedimentary rock. Erosion is at work while the mountains are being uplifted until the mountains are reduced to low hills and plains; the early Cenozoic uplift of the Rocky Mountains of Colorado provides an example. As the uplift was occurring some 10,000 feet of Mesozoic sedimentary strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to the east; this mass of rock was removed as the range was undergoing uplift. The removal of such a mass from the core of the range most caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment.
Computer simulation has shown that as mountain belts change from tectonically active to inactive, the rate of erosion drops because there are fewer abrasive particles in the water and fewer landslides. Mountains on other planets and natural satellites of the Solar System are isolated and formed by processes such as impacts, though there are examples of mountain ranges somewhat similar to those on Earth. Saturn's moon Titan and Pluto, in particular exhibit large mountain ranges in chains composed of ices rather than rock. Examples include the Mithrim Montes and Doom Mons on Titan, Tenzing Montes and Hillary Montes on Pluto; some terrestrial planets other than Earth exhibit rocky mountain ranges, such as Maxwell Montes on Venus taller than any on Earth and Tartarus Montes on Mars, Jupiter's moon Io has mountain ranges formed from tectonic processes including Boösaule Montes, Dorian Montes, Hi'iaka Montes and Euboea Montes. Peakbagger Ranges Home Page Bivouac.com
Definitions from Wiktionary
Media from Wikimedia Commons
News from Wikinews
Quotations from Wikiquote
Texts from Wikisource
Textbooks from Wikibooks
Resources from Wikiversity
