Grenville orogeny
The Grenville orogeny was a long-lived Mesoproterozoic mountain-building event associated with the assembly of the supercontinent Rodinia. Its record is a prominent orogenic belt which spans a significant portion of the North American continent, from Labrador to Mexico, as well as to Scotland. Grenville orogenic crust of mid-late Mesoproterozoic age is found worldwide, but only events which occurred on the southern and eastern margins of Laurentia are recognized under the "Grenville" name; these orogenic events are known as the Kibaran orogeny in Africa and the Dalslandian orogeny in Western Europe. The problem of timing the Grenville orogeny is an area of some contention today; the timescale outlined in Toby Rivers' recent work is derived from the well-preserved Grenville Province, represents one of the most detailed records of the orogeny. This classification considers the classical Grenville designation to cover two separate orogenic cycles. Due to the great size of the area affected by Grenville events, there is some variance in timing across the orogenic belt.
Regional variations below discusses local deviations from Rivers’ timeline, presented here. Ages are approximated from the magmatic activity associated with the individual cycles of the orogeny; the gaps in the ages of the compression cycles and isotope analysis of hornblende and potassium feldspar suggest that extension was occurring when compression had momentarily ceased. Rivers' 2008 paper has now examined the timing of the different periods of the orogeny and reconstructed the timeline based on the spatial and temporal metamorphism of the rocks present. According to this newer version of the timeline, a composite of Rivers 1997 and Gower and Krogh 2002, the Elzevirian orogeny occurs from 1240 to 1220 Ma, the Shawinigan occurs from 1190 to 1140 Ma and is no longer part of the Grenville cycle, the Ottawan and Rigolet become phases which are grouped into the Grenvillian orogeny. Reconstruction of the events of the orogeny is ongoing, but the accepted view is that the eastern and southern margins of Laurentia were active convergent margins until the beginning of continental collision.
This type of subduction tends to emplace magmatic arcs on or near the edge of the overriding plate in modern subduction zones, evidence of contemporary island arcs can be found throughout the Grenville orogen. The Andes of South America are considered a modern analogue. From about c. 1190–980 Ma two separate continental blocks collided with Laurentia. Both of these collision events are thought to be analogous to the collision driving modern-day growth of the Himalaya range. For some time one of the blocks was believed to be the continent of Amazonia, but paleomagnetic evidence has now proven that this is not the case; these periods of thrusting and metamorphism were not continuous, but rather interrupted by comparatively quiet periods, during which AMCG plutons were intruded into the country rock. Polarities of subduction vary by time; some island arc remnants were emplaced on the Laurentian margin, some were accreted during orogeny. Timing of these events is constrained by cross-cutting relations observed in the field as well as SHRIMP and TIMS uranium-lead dating.
The first period of tectonic activity was the accretion of an island arc at some point during the Elzevirian Orogeny. Before the accretion of the island arc took place, subduction between a continental plate and an oceanic plate was taking place. Slab pull and far-field drivers such as ridge push were aiding in closing the distance between the island arc and the continent. Depending on the angle of subduction deformation of the continental crust was taking place and thickening the lithosphere. By 1.19 Ga the Elzevir back arc basin was closing. From 1.18 to 1.14 Ga extension was occurring in the area. Whether due to lithospheric cooling known as thermal subsidence, or the compressional activity in the area reactivated some extensional faults; the extension is marked by the isotopic ages of the mentioned rocks. Additionally there is the formation of sedimentary basins which means the margin was quiescent enough that sediments could accumulate. However, in some areas from 1.16 to 1.13 Ga, coeval with extension, there is evidence there was still thrusting and emplacement of terranes occurring.
According to one model westward thrusting occurred from 1.12 to 1.09 Ga and extension was the primary tectonic activity until 1.05 Ga. It was at this point that the Central Granulite Terrane was exhumed and minor magmatism occurred; the precise reason for change from compression to extension is unknown but may be the result of gravitational collapse, mantle delamination, the formation of a plume underneath a supercontinent, changes in far-field drivers on the distribution of stress, or any combination of reasons originating from the fact that our planet is dynamic. The cyclic compression and extension history of this area is similar to the Wilson Cycle. In this area of the world the Wilson Cycle would be creating the basin for the proto-Atlantic Ocean Today, the Grenville orogen is marked by northwest verging fold-and-thrust belts and high pressure metamorphic regimes, as well as distinctive AMCG suite magmatism. Metamorphism is of amphibolite and granulite facies, that is, medium to high temperature and pressure alteration.
Eclogitized metagabbros (very high pressure ultramafic me
Saint Lawrence River
The Saint Lawrence River is a large river in the middle latitudes of North America. The Saint Lawrence River flows in a north-easterly direction, connecting the Great Lakes with the Atlantic Ocean and forming the primary drainage outflow of the Great Lakes Basin, it traverses the Canadian provinces of Quebec and Ontario, is part of the international boundary between Ontario and the U. S. state of New York. This river provides the basis for the commercial Saint Lawrence Seaway; the Saint Lawrence River begins at the outflow of Lake Ontario and flows adjacent to Gananoque, Morristown, Massena, Montreal, Trois-Rivières, Quebec City before draining into the Gulf of Saint Lawrence, the largest estuary in the world. The estuary begins at the eastern tip of just downstream from Quebec City; the river becomes tidal around Quebec City. The Saint Lawrence River runs 3,058 kilometres from the farthest headwater to the mouth and 1,197 km from the outflow of Lake Ontario; these numbers include the estuary. The farthest headwater is the North River in the Mesabi Range at Minnesota.
Its drainage area, which includes the Great Lakes, the world's largest system of freshwater lakes, is 1,344,200 square kilometres, of which 839,200 km2 is in Canada and 505,000 km2 is in the United States. The basin covers parts of Ontario and Quebec in Canada, parts of Illinois, Minnesota, New York, Pennsylvania and Wisconsin, nearly the entirety of the state of Michigan in the United States; the average discharge below the Saguenay River is 16,800 cubic metres per second. At Quebec City, it is 12,101 m3/s; the average discharge at the river's source, the outflow of Lake Ontario, is 7,410 m3/s. The Saint Lawrence River includes Lake Saint-Louis south of Montreal, Lake Saint Francis at Salaberry-de-Valleyfield and Lac Saint-Pierre east of Montreal, it encompasses four archipelagoes: the Thousand Islands chain near Alexandria Bay, New York and Kingston, Ontario. Other islands include Île d'Orléans near Quebec City and Anticosti Island north of the Gaspé, it is the second longest river in Canada.
Lake Champlain and the Ottawa, Saint-Maurice, Saint-François and Saguenay rivers drain into the Saint Lawrence. The Saint Lawrence River is in a seismically active zone where fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of the Iapetus Ocean; the faults in the area comprise the Saint Lawrence rift system. According to the United States Geological Survey, the Saint Lawrence Valley is a physiographic province of the larger Appalachian division, containing the Champlain and Northern physiographic section. However, in Canada, where most of the valley is, it is instead considered part of a distinct Saint Lawrence Lowlands physiographic division, not part of the Appalachian division at all; the Norse explored the Gulf of Saint Lawrence in the 11th century and were followed by fifteenth and early sixteenth century European mariners, such as John Cabot, the brothers Gaspar and Miguel Corte-Real. The first European explorer known to have sailed up the Saint Lawrence River itself was Jacques Cartier.
At that time, the land along the river was inhabited by the St. Lawrence Iroquoians; because Cartier arrived in the estuary on Saint Lawrence's feast day, he named it the Gulf of Saint Lawrence. The Saint Lawrence River is within the U. S. and as such is that country's sixth oldest surviving European place-name. The earliest regular Europeans in the area were the Basques, who came to the St Lawrence Gulf and River in pursuit of whales from the early 16th century; the Basque whalers and fishermen traded with indigenous Americans and set up settlements, leaving vestiges all over the coast of eastern Canada and deep into the Saint Lawrence River. Basque commercial and fishing activity reached its peak before the Armada Invencible's disaster, when the Spanish Basque whaling fleet was confiscated by King Philip II of Spain and destroyed; the whaling galleons from Labourd were not affected by the Spanish defeat. Until the early 17th century, the French used the name Rivière du Canada to designate the Saint Lawrence upstream to Montreal and the Ottawa River after Montreal.
The Saint Lawrence River served as the main route for European exploration of the North American interior, first pioneered by French explorer Samuel de Champlain. Control of the river was crucial to British strategy to capture New France in the Seven Years' War. Having captured Louisbourg in 1758, the British sailed up to Quebec the following year thanks to charts drawn up by James Cook. British troops were ferried via the Saint Lawrence to attack the city from the west, which they did at the Battle of the Plains of Abraham; the river was used again by the British to defeat the French siege of Quebec under the Chevalier de Lévis in 1760. In 1809, the first steamboat to ply its trade on the St. Lawrence was built and operated by John Molson and associates, a scant two years after Fulton's steam-powered navigation of the Hudson River; the Accommodation with ten passengers made her maiden voyage from Montreal to Quebec City in 66 hours, for 30 of which she was at anch
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
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
New York (state)
New York is a state in the Northeastern United States. New York was one of the original thirteen colonies. With an estimated 19.54 million residents in 2018, it is the fourth most populous state. To distinguish the state from the city with the same name, it is sometimes called New York State; the state's most populous city, New York City, makes up over 40% of the state's population. Two-thirds of the state's population lives in the New York metropolitan area, nearly 40% lives on Long Island; the state and city were both named for the 17th century Duke of York, the future King James II of England. With an estimated population of 8.62 million in 2017, New York City is the most populous city in the United States and the premier gateway for legal immigration to the United States. The New York metropolitan area is one of the most populous in the world. New York City is a global city, home to the United Nations Headquarters and has been described as the cultural and media capital of the world, as well as the world's most economically powerful city.
The next four most populous cities in the state are Buffalo, Rochester and Syracuse, while the state capital is Albany. The 27th largest U. S. state in land area, New York has a diverse geography. The state is bordered by New Jersey and Pennsylvania to the south and Connecticut and Vermont to the east; the state has a maritime border with Rhode Island, east of Long Island, as well as an international border with the Canadian provinces of Quebec to the north and Ontario to the northwest. The southern part of the state is in the Atlantic coastal plain and includes Long Island and several smaller associated islands, as well as New York City and the lower Hudson River Valley; the large Upstate New York region comprises several ranges of the wider Appalachian Mountains, the Adirondack Mountains in the Northeastern lobe of the state. Two major river valleys – the north-south Hudson River Valley and the east-west Mohawk River Valley – bisect these more mountainous regions. Western New York is considered part of the Great Lakes region and borders Lake Ontario, Lake Erie, Niagara Falls.
The central part of the state is dominated by the Finger Lakes, a popular vacation and tourist destination. New York had been inhabited by tribes of Algonquian and Iroquoian-speaking Native Americans for several hundred years by the time the earliest Europeans came to New York. French colonists and Jesuit missionaries arrived southward from Montreal for trade and proselytizing. In 1609, the region was visited by Henry Hudson sailing for the Dutch East India Company; the Dutch built Fort Nassau in 1614 at the confluence of the Hudson and Mohawk rivers, where the present-day capital of Albany developed. The Dutch soon settled New Amsterdam and parts of the Hudson Valley, establishing the multicultural colony of New Netherland, a center of trade and immigration. England seized the colony from the Dutch in 1664. During the American Revolutionary War, a group of colonists of the Province of New York attempted to take control of the British colony and succeeded in establishing independence. In the 19th century, New York's development of access to the interior beginning with the Erie Canal, gave it incomparable advantages over other regions of the U.
S. built its political and cultural ascendancy. Many landmarks in New York are well known, including four of the world's ten most-visited tourist attractions in 2013: Times Square, Central Park, Niagara Falls, Grand Central Terminal. New York is home to the Statue of Liberty, a symbol of the United States and its ideals of freedom and opportunity. In the 21st century, New York has emerged as a global node of creativity and entrepreneurship, social tolerance, environmental sustainability. New York's higher education network comprises 200 colleges and universities, including Columbia University, Cornell University, New York University, the United States Military Academy, the United States Merchant Marine Academy, University of Rochester, Rensselaer Polytechnic Institute, Rockefeller University, which have been ranked among the top 40 in the nation and world; the tribes in what is now New York were predominantly Algonquian. Long Island was divided in half between the Wampanoag and Lenape; the Lenape controlled most of the region surrounding New York Harbor.
North of the Lenape was the Mohicans. Starting north of them, from east to west, were three Iroquoian nations: the Mohawk, the original Iroquois and the Petun. South of them, divided along Appalachia, were the Susquehannock and the Erie. Many of the Wampanoag and Mohican peoples were caught up in King Philip's War, a joint effort of many New England tribes to push Europeans off their land. After the death of their leader, Chief Philip Metacomet, most of those peoples fled inland, splitting into the Abenaki and the Schaghticoke. Many of the Mohicans remained in the region until the 1800s, however, a small group known as the Ouabano migrated southwest into West Virginia at an earlier time, they may have merged with the Shawnee. The Mohawk and Susquehannock were the most militaristic. Trying to corner trade with the Europeans, they targeted other tribes; the Mohawk were known for refusing white settlement on their land and banishing any of their people who converted to Christianity. They posed a major threat to the Abenaki and Mohicans, while the Susquehannock conquered the Lenape in the 1600s.
The most devastating event of the century, was the Beaver Wars. From 1640–1680, Iroquoian peoples waged campaigns which extended from modern-day Michigan to Virginia against Algonquian and Siouan tribes, as well as each other; the ai
Mont Blanc, Quebec
Mont Blanc is a ski resort in the Laurentian Mountains and south of Mont-Tremblant in Quebec, Canada. It is located in the municipality of Saint-Faustin–Lac-Carré, just east of Mont Tremblant; the ski resort 41 trails as well as a snow park. It offers a wide variety of trails suitable for all levels of snowboarders; the resort is owned by American lawyer Phillip Robinson since 1976. It is run by his two sons and Michael Robinson
