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
The Russian-American Company Under the Supreme Patronage of His Imperial Majesty was a state-sponsored chartered company formed on the basis of the United American Company. The company was chartered by Tsar Paul I in the Ukase of 1799, its mission was to establish new settlements in Russian America, conduct trade with natives, carry out an expanded colonization program. This was Russia's first joint-stock company, it came under the direct authority of the Ministry of Commerce of Imperial Russia; the Minister of Commerce Nikolai Petrovich Rumyantsev was a pivotal influence upon the early Company's affairs. In 1801, the company's headquarters were moved from Irkutsk to Saint Petersburg, the merchants who were the major stockholders were soon replaced by Russia's nobility and aristocracy. Count Rumyantsev funded Russia's first naval circumnavigation under the joint command of Adam Johann von Krusenstern and Nikolai Rezanov in 1803–1806, he funded and directed the voyage of the Ryurik's circumnavigation of 1814–1816, which provided substantial scientific information on Alaska's and California's flora and fauna, important ethnographic information on Alaskan and Californian natives.
During the Russian-California period when they operated Fort Ross, the Russians named present-day Bodega Bay, California as "Rumyantsev Bay" in his honor. In 1799 the Russian government appointed an official, with the title'Correspondent', to maintain oversight of company affairs, the first being Nikolai Rezanov; this role was soon expanded to a three-seat board of directors, with two elected by the stockholders and one appointed by the government. Additionally the directors had to send reports of the company's activities directly to the tsar, they appointed a Chief Manager of the company, stationed in North America to directly administer the forts, trade stations and outposts. Alexander Andreyevich Baranov was appointed as the first Chief Manager. During his tenure, he founded both Pavlovskaya and New Archangel, settlements that became operating bases for the company, he was replaced in 1818 by an officer appointed from the Imperial Russian Navy. The position of Chief Manager was thereafter reserved for Imperial Naval officers.
The Ukase of 1799 granted the company a monopoly over trade in Russian America, defined with a southern border of 55° N latitude. Tsar Alexander I in the Ukase of 1821 asserted its domain to 45°50′ N latitude, revised by 1822 to 51° N latitude; this border was challenged by both Great Britain and the United States, which resulted in the Russo-American Treaty of 1824 and the Russo-British Treaty of 1825. These established 54°40′ as the ostensible southward limit of Russian interests; the only attempt by the Russians to enforce the ukase of 1821 was the seizure of the U. S. brig Pearl in 1822, by the Russian sloop Apollon. The Pearl, a vessel of the maritime fur trade, was sailing from Boston, Massachusetts to New Archangel/Sitka; when the U. S. government protested, the Russians paid compensation. Due to treaty violations in 1833 with the British by the company's governor, Baron Ferdinand von Wrangel, the Russians leased the southeastern sector of what is now the Alaska Panhandle, to the Hudson's Bay Company in 1838 as part of a damages settlement.
The lease gave the HBC authority as far north as 56° 30' N. Under Baranov, who governed the region between 1790 and 1818, a permanent settlement was established in 1804 at "Novo-Arkhangelsk", a thriving maritime trade was organized. Alutiiq and Aleut men from the Kodiak and the Aleutian Islands were forcibly conscripted to work for the company for three-year periods because they were "among the most sophisticated and effective sea otter hunters in the world." During its initial years, the company had problems in maintaining a pool of skilled crewmen for its ships. The limited number of Russian men proficient in naval craft in the Empire sought employment in the Imperial Russian Navy; the RAC had difficulty recruiting men for naval training, in part due to the continued practise of serfdom in the Empire, which kept most peasants tied to the land. In 1802 the Imperial government directed the Imperial Navy to send officers for employment in the RAC, with half of their pay to come from the company.
Russian merchants were excluded from the port of Guangzhou and its valuable markets, something the RAC endeavoured to change. The company funded a circumnavigation that lasted from 1803 to 1806, with the goals of expanding Russian navigational knowledge, supplying the RAC stations, opening commercial relations with the Qing Empire. While the expedition did sell its wares at the Chinese port, "no noticeable progress" towards securing Russian trading rights was made during the next half century. Due to the closed Chinese ports, the RAC had to ship its furs to the Russian port of Okhotsk. From there caravans took more than a year to reach Ayan and the Siberian Route; the majority of the pelts were traded in Kyakhta, where Chinese trade goods, principally cotton and tea, were traded. Fort Elizabeth was built in Hawaii by Georg Anton Schäffer, an agent of the RAC, his actions to attempt to overthrow the Kingdom of Hawaii is known as the Schäffer affair. Over the course of the RAC's first decade of enterprise, its officials became concerned about American ships trading in adjacent coastal regions their sale of firearms to natives.
Throughout 1808 to 1810
The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west and the Americas in the east. At 165,250,000 square kilometers in area, this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about one-third of its total surface area, making it larger than all of Earth's land area combined; the centers of both the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean. The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific, its mean depth is 4,000 meters. The Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 meters; the western Pacific has many peripheral seas. Though the peoples of Asia and Oceania have traveled the Pacific Ocean since prehistoric times, the eastern Pacific was first sighted by Europeans in the early 16th century when Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and discovered the great "southern sea" which he named Mar del Sur.
The ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favorable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means "peaceful sea". Important human migrations occurred in the Pacific in prehistoric times. About 3000 BC, the Austronesian peoples on the island of Taiwan mastered the art of long-distance canoe travel and spread themselves and their languages south to the Philippines and maritime Southeast Asia. Long-distance trade developed all along the coast from Mozambique to Japan. Trade, therefore knowledge, extended to the Indonesian islands but not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of this trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality. From 1404 to 1433 Zheng He led expeditions into the Indian Ocean; the first contact of European navigators with the western edge of the Pacific Ocean was made by the Portuguese expeditions of António de Abreu and Francisco Serrão, via the Lesser Sunda Islands, to the Maluku Islands, in 1512, with Jorge Álvares's expedition to southern China in 1513, both ordered by Afonso de Albuquerque from Malacca.
The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and reached a new ocean. He named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. In 1519, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Spanish expedition to the Spice Islands that would result in the first world circumnavigation. Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters; the ocean was called the Sea of Magellan in his honor until the eighteenth century. Although Magellan himself died in the Philippines in 1521, Spanish Basque navigator Juan Sebastián Elcano led the remains of the expedition back to Spain across the Indian Ocean and round the Cape of Good Hope, completing the first world circumnavigation in a single expedition in 1522. Sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, Papua New Guinea.
In 1542–43 the Portuguese reached Japan. In 1564, five Spanish ships carrying 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi, sailed to the Philippines and Mariana Islands. For the remainder of the 16th century, Spanish influence was paramount, with ships sailing from Mexico and Peru across the Pacific Ocean to the Philippines via Guam, establishing the Spanish East Indies; the Manila galleons operated for two and a half centuries, linking Manila and Acapulco, in one of the longest trade routes in history. Spanish expeditions discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, the Admiralty Islands in the South Pacific. In the quest for Terra Australis, Spanish explorations in the 17th century, such as the expedition led by the Portuguese navigator Pedro Fernandes de Queirós, discovered the Pitcairn and Vanuatu archipelagos, sailed the Torres Strait between Australia and New Guinea, named after navigator Luís Vaz de Torres. Dutch explorers, sailing around southern Africa engaged in discovery and trade.
In the 16th and 17th centuries Spain considered the Pacific Ocean a mare clausum—a sea closed to other naval powers. As the only known entrance from the Atlantic, the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western side of the Pacific Ocean the Dutch threatened the Spanish Philippines; the 18th cen
Alaska is a U. S. state in the northwest extremity of North America, just across the Bering Strait from Asia. The Canadian province of British Columbia and territory of Yukon border the state to the east and southeast, its most extreme western part is Attu Island, it has a maritime border with Russia to the west across the Bering Strait. To the north are the Chukchi and Beaufort seas—southern parts of the Arctic Ocean; the Pacific Ocean lies to southwest. It is the largest U. S. state by the seventh largest subnational division in the world. In addition, it is the most sparsely populated of the 50 United States. Half of Alaska's residents live within the Anchorage metropolitan area. Alaska's economy is dominated by the fishing, natural gas, oil industries, resources which it has in abundance. Military bases and tourism are a significant part of the economy; the United States purchased Alaska from the Russian Empire on March 30, 1867, for 7.2 million U. S. dollars at two cents per acre. The area went through several administrative changes before becoming organized as a territory on May 11, 1912.
It was admitted as the 49th state of the U. S. on January 3, 1959. The name "Alaska" was introduced in the Russian colonial period when it was used to refer to the Alaska Peninsula, it was derived from an Aleut-language idiom. It means object to which the action of the sea is directed. Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U. S. state on continental North America. It is technically part of the continental U. S. but is sometimes not included in colloquial use. S. called "the Lower 48". The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system; the state is bordered by Yukon and British Columbia in Canada, to the east, the Gulf of Alaska and the Pacific Ocean to the south and southwest, the Bering Sea, Bering Strait, Chukchi Sea to the west and the Arctic Ocean to the north.
Alaska's territorial waters touch Russia's territorial waters in the Bering Strait, as the Russian Big Diomede Island and Alaskan Little Diomede Island are only 3 miles apart. Alaska has a longer coastline than all the other U. S. states combined. Alaska is the largest state in the United States by total area at 663,268 square miles, over twice the size of Texas, the next largest state. Alaska is larger than all but 18 sovereign countries. Counting territorial waters, Alaska is larger than the combined area of the next three largest states: Texas and Montana, it is larger than the combined area of the 22 smallest U. S. states. There are no defined borders demarcating the various regions of Alaska, but there are six accepted regions: The most populous region of Alaska, containing Anchorage, the Matanuska-Susitna Valley and the Kenai Peninsula. Rural unpopulated areas south of the Alaska Range and west of the Wrangell Mountains fall within the definition of South Central, as do the Prince William Sound area and the communities of Cordova and Valdez.
Referred to as the Panhandle or Inside Passage, this is the region of Alaska closest to the rest of the United States. As such, this was where most of the initial non-indigenous settlement occurred in the years following the Alaska Purchase; the region is dominated by the Alexander Archipelago as well as the Tongass National Forest, the largest national forest in the United States. It contains the state capital Juneau, the former capital Sitka, Ketchikan, at one time Alaska's largest city; the Alaska Marine Highway provides a vital surface transportation link throughout the area, as only three communities enjoy direct connections to the contiguous North American road system. Designated in 1963; the Interior is the largest region of Alaska. Fairbanks is the only large city in the region. Denali National Park and Preserve is located here. Denali is the highest mountain in North America. Southwest Alaska is a sparsely inhabited region stretching some 500 miles inland from the Bering Sea. Most of the population lives along the coast.
Kodiak Island is located in Southwest. The massive Yukon–Kuskokwim Delta, one of the largest river deltas in the world, is here. Portions of the Alaska Peninsula are considered part of Southwest, with the remaining portions included with the Aleutian Islands; the North Slope is tundra peppered with small villages. The area is known for its massive reserves of crude oil, contains both the National Petroleum Reserve–Alaska and the Prudhoe Bay Oil Field; the city of Utqiagvik known as Barrow, is the northernmost city in the United States and is located here. The Northwest Arctic area, anchored by Kotzebue and containing the Kobuk River valley, is regarded as being part of this region. However, the respective Inupiat of the No
Wrangell–St. Elias National Park and Preserve
Wrangell–St. Elias National Park and Preserve is an American national park and preserve managed by the National Park Service in south central Alaska; the park and preserve were established in 1980 by the Alaska National Interest Lands Conservation Act. The protected areas are included in an International Biosphere Reserve and are part of the Kluane/Wrangell–St. Elias/Glacier Bay/Tatshenshini-Alsek UNESCO World Heritage Site; the park and preserve form the largest area managed by the National Park Service with a total of 13,175,799 acres, an expanse that could encapsulate a total of six Yellowstone National Parks. The park includes a large portion of the Saint Elias Mountains, which include most of the highest peaks in the United States and Canada, yet are within 10 miles of tidewater, one of the highest reliefs in the world. Wrangell–St. Elias borders on Canada's Kluane National Park and Reserve to the east and approaches another American national park to the south, Glacier Bay; the chief distinction between park and preserve lands is that sport hunting is prohibited in the park and permitted in the preserve.
In addition, 9,078,675 acres of the park are designated as the largest single wilderness in the United States. Wrangell–St. Elias National Monument was designated on December 1, 1978, by President Jimmy Carter using the Antiquities Act, pending final legislation to resolve the allotment of public lands in Alaska. Establishment as a national park and preserve followed the passage of the Alaska National Interest Lands Conservation Act in 1980; the park has long cold winters and a short summer season. Plate tectonics are responsible for the uplift of the mountain ranges; the park's extreme high point is Mount Saint Elias at 18,008 feet, the second tallest mountain in both the United States and Canada. The park has been shaped by the competing forces of glaciation. Mount Wrangell is one of several volcanoes in the western Wrangell Mountains. In the St. Elias Range, Mount Churchill has erupted explosively within the past 2,000 years; the park's glacial features include Malaspina Glacier, the largest piedmont glacier in North America, Hubbard Glacier, the longest tidewater glacier in Alaska, Nabesna Glacier, the world's longest valley glacier.
The Bagley Icefield covers much of the park's interior, which includes 60% of the permanently ice-covered terrain in Alaska. At the center of the park, the boomtown of Kennecott exploited one of the world's richest deposits of copper from 1903 to 1938, exposed by and in part incorporated into Kennicott Glacier; the abandoned mine buildings and mills comprise a National Historic Landmark district. Wrangell–St. Elias National Park and Preserve includes the entire Wrangell range, the western portion of the Saint Elias Mountains and the eastern portion of the Chugach Mountains. Lesser ranges in the park or preserve include the Nutzotin Mountains, which are an extension of the Alaska Range, the Granite Range and the Robinson Mountains. Broad rivers run in glacial valleys between the ranges, including the Chitina River, Chisana River and the Nabesna River. All but the Chisana and Nabesna are tributaries to the Copper River, which flows along the western margin of the park and which has its headwaters within the park, at the Copper Glacier.
The park includes dozens of icefields. The Bagley Icefield covers portions of the St. Elias and Chugach ranges, Malaspina Glacier covers most of the southeastern extension of the park, with Hubbard Glacier at the park's extreme eastern boundary, the largest tidewater glacier in North America; the eastern boundary of the park is Alaska's border with Canada, where it is adjoined by Kluane National Park and Reserve. On the southeast the park is bounded by Tongass National Forest and the Gulf of Alaska; the remainder of the southern boundary follows the crest of the Chugach Mountains, adjoining Chugach National Forest. The western boundary is the Copper River, the northern boundary follows the Mentasta Mountains and borders Tetlin National Wildlife Refuge. Mount St. Elias is the second highest mountain in the United States. In total nine of the 16 highest peaks on U. S. soil are located in the park, along with North America's largest subpolar icefield, rivers, an active volcano, the historic Kennecott copper mines.
Both the St. Elias and Wrangell ranges have seen volcanic activity; the St. Elias volcanoes are considered extinct, but some of the volcanoes of the Wrangell Range have been active in Holocene time. Ten separate volcanoes have been documented in the western Wrangell Range, of which Mount Blackburn is the highest and Mount Wrangell is the most active. Mount St. Elias is situated on the border of Wrangell–St. Elias National Park and Kluane National Park and Reserve. At 18,074 feet,Nearly 66 percent of park and preserve land is designated as wilderness. Wrangell–St. Elias Wilderness is the largest designated wilderness in the United States; the park region is divided between national park lands, which only allow subsistence hunting by local rural residents, preserve lands, which allow sport hunting by the general public. Preserve lands include the Chitina valley north of the river, two parts of the Copper River valley east of the river, most of the Chisana and Nabesna valleys, lands along Yakutat Bay.
The park is accessible by highway from Anchorage. Chartered aircraft fly into the park. Wrangell–St. Elias received 79,450 visitors in 2018; the park area includes a few small settlements. Nabesna and Chisana are in the nort
For the extinct cephalopod genus, see Andesites. Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and rhyolite, ranges from 57 to 63% silicon dioxide as illustrated in TAS diagrams; the mineral assemblage is dominated by plagioclase plus pyroxene or hornblende. Magnetite, apatite, ilmenite and garnet are common accessory minerals. Alkali feldspar may be present in minor amounts; the quartz-feldspar abundances in andesite and other volcanic rocks are illustrated in QAPF diagrams. Classification of andesites may be refined according to the most abundant phenocryst. Example: hornblende-phyric andesite, if hornblende is the principal accessory mineral. Andesite can be considered as the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs; the average composition of the continental crust is andesitic.
Along with basalts they are a major component of the Martian crust. The name andesite is derived from the Andes mountain range. Magmatism in island arc regions comes from the interplay of the subducting plate and the mantle wedge, the wedge-shaped region between the subducting and overriding plates. During subduction, the subducted oceanic crust is submitted to increasing pressure and temperature, leading to metamorphism. Hydrous minerals such as amphibole, chlorite etc. dehydrate as they change to more stable, anhydrous forms, releasing water and soluble elements into the overlying wedge of mantle. Fluxing water into the wedge lowers the solidus of the mantle material and causes partial melting. Due to the lower density of the molten material, it rises through the wedge until it reaches the lower boundary of the overriding plate. Melts generated in the mantle wedge are of basaltic composition, but they have a distinctive enrichment of soluble elements which are contributed from sediment that lies at the top of the subducting plate.
Although there is evidence to suggest that the subducting oceanic crust may melt during this process, the relative contribution of the three components to the generated basalts is still a matter of debate. Basalt thus formed can contribute to the formation of andesite through fractional crystallization, partial melting of crust, or magma mixing, all of which are discussed next. Andesite is formed at convergent plate margins but may occur in other tectonic settings. Intermediate volcanic rocks are created via several processes: Fractional crystallization of a mafic parent magma. Partial melting of crustal material. Magma mixing between felsic rhyolitic and mafic basaltic magmas in a magma reservoir To achieve andesitic composition via fractional crystallization, a basaltic magma must crystallize specific minerals that are removed from the melt; this removal can take place in a variety of ways, but most this occurs by crystal settling. The first minerals to crystallize and be removed from a basaltic parent are amphiboles.
These mafic minerals settle out of the magma. There is geophysical evidence from several arcs that large layers of mafic cumulates lie at the base of the crust. Once these mafic minerals have been removed, the melt no longer has a basaltic composition; the silica content of the residual melt is enriched relative to the starting composition. The iron and magnesium contents are depleted; as this process continues, the melt becomes more and more evolved becoming andesitic. Without continued addition of mafic material, the melt will reach a rhyolitic composition. Molten basalt in the mantle wedge moves upwards until it reaches the base of the overriding crust. Once there, the basaltic melt can either underplate the crust, creating a layer of molten material at its base, or it can move into the overriding plate in the form of dykes. If it underplates the crust, the basalt can cause partial melting of the lower crust due to the transfer of heat and volatiles. Models of heat transfer, show that arc basalts emplaced at temperatures 1100–1240 °C cannot provide enough heat to melt lower crustal amphibolite.
Basalt can, melt pelitic upper crustal material. Andesitic magmas generated in island arcs, are the result of partial melting of the crust. In continental arcs, such as the Andes, magma pools in the shallow crust creating magma chambers. Magmas in these reservoirs become evolved in composition through both the process of fractional crystallization and partial melting of the surrounding country rock. Over time as crystallization continues and the system loses heat, these reservoirs cool. In order to remain active, magma chambers must have continued recharge of hot basaltic melt into the system; when this basaltic material mixes with the evolved rhyolitic magma, the composition is returned to andesite, its intermediate phase. In 2009, researchers revealed that andesite was found in two meteorites that were discovered in the Graves Nunataks icefield during the US Antarctic Search for Meteorites 2006/2007 field season; this points to a new mechanism to generate andesite crust. Andesite line Basaltic andesite Continental crust – Layer of rock that forms the continents and continental shelves Fractional crystallization – One of the main processes of magmatic differentiation List of rock types – A list of rock types recognized by geologists Metamorphism – The change of minerals in pre-existing rocks w
Cambridge University Press
Cambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the world's oldest publishing house and the second-largest university press in the world, it holds letters patent as the Queen's Printer. The press mission is "to further the University's mission by disseminating knowledge in the pursuit of education and research at the highest international levels of excellence". Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. With a global sales presence, publishing hubs, offices in more than 40 countries, it publishes over 50,000 titles by authors from over 100 countries, its publishing includes academic journals, reference works and English language teaching and learning publications. Cambridge University Press is a charitable enterprise that transfers part of its annual surplus back to the university. Cambridge University Press is both the oldest publishing house in the world and the oldest university press.
It originated from letters patent granted to the University of Cambridge by Henry VIII in 1534, has been producing books continuously since the first University Press book was printed. Cambridge is one of the two privileged presses. Authors published by Cambridge have included John Milton, William Harvey, Isaac Newton, Bertrand Russell, Stephen Hawking. University printing began in Cambridge when the first practising University Printer, Thomas Thomas, set up a printing house on the site of what became the Senate House lawn – a few yards from where the press's bookshop now stands. In those days, the Stationers' Company in London jealously guarded its monopoly of printing, which explains the delay between the date of the university's letters patent and the printing of the first book. In 1591, Thomas's successor, John Legate, printed the first Cambridge Bible, an octavo edition of the popular Geneva Bible; the London Stationers objected strenuously. The university's response was to point out the provision in its charter to print "all manner of books".
Thus began the press's tradition of publishing the Bible, a tradition that has endured for over four centuries, beginning with the Geneva Bible, continuing with the Authorized Version, the Revised Version, the New English Bible and the Revised English Bible. The restrictions and compromises forced upon Cambridge by the dispute with the London Stationers did not come to an end until the scholar Richard Bentley was given the power to set up a'new-style press' in 1696. In July 1697 the Duke of Somerset made a loan of £200 to the university "towards the printing house and presse" and James Halman, Registrary of the University, lent £100 for the same purpose, it was in Bentley's time, in 1698, that a body of senior scholars was appointed to be responsible to the university for the press's affairs. The Press Syndicate's publishing committee still meets and its role still includes the review and approval of the press's planned output. John Baskerville became University Printer in the mid-eighteenth century.
Baskerville's concern was the production of the finest possible books using his own type-design and printing techniques. Baskerville wrote, "The importance of the work demands all my attention. Caxton would have found nothing to surprise him if he had walked into the press's printing house in the eighteenth century: all the type was still being set by hand. A technological breakthrough was badly needed, it came when Lord Stanhope perfected the making of stereotype plates; this involved making a mould of the whole surface of a page of type and casting plates from that mould. The press was the first to use this technique, in 1805 produced the technically successful and much-reprinted Cambridge Stereotype Bible. By the 1850s the press was using steam-powered machine presses, employing two to three hundred people, occupying several buildings in the Silver Street and Mill Lane area, including the one that the press still occupies, the Pitt Building, built for the press and in honour of William Pitt the Younger.
Under the stewardship of C. J. Clay, University Printer from 1854 to 1882, the press increased the size and scale of its academic and educational publishing operation. An important factor in this increase was the inauguration of its list of schoolbooks. During Clay's administration, the press undertook a sizeable co-publishing venture with Oxford: the Revised Version of the Bible, begun in 1870 and completed in 1885, it was in this period as well that the Syndics of the press turned down what became the Oxford English Dictionary—a proposal for, brought to Cambridge by James Murray before he turned to Oxford. The appointment of R. T. Wright as Secretary of the Press Syndicate in 1892 marked the beginning of the press's development as a modern publishing business with a defined editorial policy and administrative structure, it was Wright who devised the plan for one of the most distinctive Cambridge contributions to publishing—the Cambridge Histories. The Cambridge Modern History was published