A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator; the strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell. Bells are cast from bell metal for its resonant properties, but can be made from other hard materials; some small bells such as ornamental bells or cow bells can be made from cast or pressed metal, glass or ceramic, but large bells such as church and tower bells are cast from bell metal. Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installed in a bell tower. Many public or institutional buildings house bells, most as clock bells to sound the hours and quarters.
Bells have been associated with religious rites, are still used to call communities together for religious services. Bells were made to commemorate important events or people and have been associated with the concepts of peace and freedom; the study of bells is called campanology. Bell is a word common to the Low German dialects, cognate with Middle Low German belle and Dutch bel but not appearing among the other Germanic languages except the Icelandic bjalla, a loanword from Old English, it is popularly but not related to the former sense of to bell which gave rise to bellow. The earliest archaeological evidence of bells dates from the 3rd millennium BC, is traced to the Yangshao culture of Neolithic China. Clapper-bells made of pottery have been found in several archaeological sites; the pottery bells developed into metal bells. In West Asia, the first bells appear in 1000 BC; the earliest metal bells, with one found in the Taosi site and four in the Erlitou site, are dated to about 2000 BC. Early bells not only have an important role in generating metal sound, but arguably played a prominent cultural role.
With the emergence of other kinds of bells during the Shang Dynasty, they were relegated to subservient functions. The book of Exodus in the Bible notes that small gold bells were worn as ornaments on the hem of the robe of the high priest in Jerusalem. Among the ancient Greeks, hand bells were used in camps and garrisons and by patrols that went around to visit sentinals. Among the Romans, the hour of bathing was announced by a bell, they used them in the home, as an ornament and emblem, bells were placed around the necks of cattle and sheep so they could be found if they strayed. See Klang Bell of the British Museum collection. In the western world, the common form of bell is a church bell or town bell, hung within a tower or bell cote; such bells are either mounted on a beam so they can swing to and fro. Bells that are hung dead are sounded by hitting the sound bow with a hammer or by pulling an internal clapper against the bell. Where a bell is swung it can either be swung over a small arc by a rope and lever or by using a rope on a wheel to swing the bell higher.
As the bell swings higher the sound is projected outwards rather than downwards. Larger bells may be swung using electric motors. In some places, such as Salzburg Cathedral the clappers are held against the sound bow whilst the bells are raised released sequentially to give a clean start to the ringing. At the end they are successively caught again by the mechanism to silence the bells. Bells hung for full circle ringing are swung through just over a complete circle from mouth uppermost. A stay engages a mechanism to allow the bell to rest just past its balance point; the rope is attached to one side of a wheel so that a different amount of rope is wound on and off as it swings to and fro. The bells are controlled by ringers in a chamber below, who rotate the bell to through a full circle and back, control the speed of oscillation when the bell is mouth upwards at the balance-point, when little effort is required. Swinging bells are sounded by an internal clapper; the clapper may have a longer period of swing than the bell.
In this case the bell will catch up with the clapper and if rung to or near full circle will carry the clapper up on the bell's trailing side. Alternatively, the clapper may have a shorter period and catch up with the bell's leading side, travel up with the bell coming to rest on the downhill side; this latter method is used in English style full circle ringing. The clappers have leather pads strapped around them to quieten the bells when practice ringing to avoid annoying the neighbourhood. At funerals, half-muffles are used to give a full open sound on one round, a muffled sound on the alternate round – a distinctive, mournful effect; this was done at the Funeral of Diana, Princess of Wales in 1997. A carillon, a musical instrument consisting of at least 23 cast bronze cup-shaped bells, is tuned so that the bells can be played serially to produce a melody, or sounded together to play a chord. A traditional carillon is played by striking a baton keyboard with the fists, by pressing the keys of a pedal keyboard with the feet.
The keys mechanically activate levers and wires that connect to meta
A butter churn is a device used to convert cream into butter. This is done through a mechanical process via a pole inserted through the lid of the churn, or via a crank used to turn a rotating device inside the churn; the word “butter” is believed to be derived from the Greek word bou-tyron, the approximate meaning of, “cow cheese”. However, some believe the word came from the Scythian culture, as the ancient Greeks tended to herd sheep and goats, whose milk is not as good for butter making as that of cows, which the Scythians herded; the word "churn" is from the Old English ċyrin. This is derived from the Old English cyrnel, "kernel," due to the appearance of butter grains after milk has been churned; the butter churn gave its name to the milk churn, early examples of which were based on butter churns. The milk churn is not, used for the act of churning, but rather to transport milk. Evidence for the use of butter dates back as early as 2000 BC, there is mention of it in biblical works; the butter churn itself may have existed as early as the 6th century AD, as can be seen by what appears to be a churn lid dating from that era.
In the European tradition, the butter churn was a device used by women, the churning of butter was an essential responsibility along with other household chores. In earlier traditions of butter making, nomadic cultures placed milk in skin bags and produced butter either by shaking the bag manually, or by attaching the bag to a pack animal, producing butter through the movement of the animal; some theorists believe. Some cultures still use a process similar to this, whereby a bag is filled with milk, tied to a stick, vigorously shaken; the most prominent types of butter churns are the plunge churn, a container made out of wood, where the butter-making action is created by moving in a vertical motion a staff, inserted into the top. This type of churn is known as an ‘up and down’ churn, churning tub, plunger churn, plumping churn, knocker churn, plump-kirn, or plowt-kirn; the staff used in the churn is known as the dash, dasher-staff, churn-staff, churning-stick, plumper, or kirn-staff. Another prominent type of churn was the paddle churn, a container that contained a paddle, operated by a handle.
The paddle churned the butter inside the container. The barrel churn was used extensively; this type of churn was a barrel turned onto its side with a crank attached. The crank either turned a paddle device inside the churn, as in the paddle churn, or turned the whole barrel, whose action converted the milk to butter; the barrel churn. One novel invention of note was the rocking chair butter churn; this device, invented by Alfred Clark, consisted of a barrel attached to a rocking chair. While the rocking chair moved, the barrel churned the milk within into butter. Butter-churn tower, named after its similarity to a type of butter churn. Several types of butter churn illustrated and described Traditional Czech butter churn
Limestone is a carbonate sedimentary rock, composed of the skeletal fragments of marine organisms such as coral and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate. A related rock is dolostone, which contains a high percentage of the mineral dolomite, CaMg2. In fact, in old USGS publications, dolostone was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolostones or magnesium-rich limestones. About 10% of sedimentary rocks are limestones; the solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock. Limestone has numerous uses: as a building material, an essential component of concrete, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, or as a popular decorative addition to rock gardens.
Like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of marine organisms such as foraminifera; these organisms secrete shells made of aragonite or calcite, leave these shells behind when they die. Other carbonate grains composing limestones are ooids, peloids and extraclasts. Limestone contains variable amounts of silica in the form of chert or siliceous skeletal fragment, varying amounts of clay and sand carried in by rivers; some limestones do not consist of grains, are formed by the chemical precipitation of calcite or aragonite, i.e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters; this produces speleothems, such as stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance; the primary source of the calcite in limestone is most marine organisms. Some of these organisms can construct mounds of rock building upon past generations. Below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone does not form in deeper waters.
Limestones may form in lacustrine and evaporite depositional environments. Calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, dissolved ion concentrations. Calcite exhibits an unusual characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors with weathered surfaces. Limestone may be crystalline, granular, or massive, depending on the method of formation. Crystals of calcite, dolomite or barite may line small cavities in the rock; when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams where there are waterfalls and around hot or cold springs. Calcium carbonate is deposited where evaporation of the water leaves a solution supersaturated with the chemical constituents of calcite.
Tufa, a porous or cellular variety of travertine, is found near waterfalls. Coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the mountain building process, limestone recrystallizes into marble. Limestone is a parent material of Mollisol soil group. Two major classification schemes, the Folk and the Dunham, are used for identifying the types of carbonate rocks collectively known as limestone. Robert L. Folk developed a classification system that places primary emphasis on the detailed composition of grains and interstitial material in carbonate rocks. Based on composition, there are three main components: allochems and cement; the Folk system uses two-part names. It is helpful to have a petrographic microscope when using the Folk scheme, because it is easier to determine the components present in each sample; the Dunham scheme focuses on depositional textures. Each name is based upon the texture of the grains. Robert J. Dunham published his system for limestone in 1962.
Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles. Dunham names are for rock families, his efforts deal with the question of whether or not the grains were in mutual contact, therefore self-supporting, or whether the rock is characterized by the presence of frame builders and algal mats. Unlike the Folk scheme, Dunham deals with the original porosity of the rock; the Dunham scheme is more useful for hand samples because it is based on texture, not the grains in the sample. A revised classification was proposed by Wright, it adds some diagenetic patterns and can be summarized as follows: See: Carbonate platform About 10% of all sedimentary rocks are limestones. Limestone is soluble in acid, therefore forms many erosional landforms; these include limestone pavements, pot holes, cenotes and gorges. Such erosion landscapes are known
Norfolk and Western Railway
The Norfolk and Western Railway was a US class I railroad, formed by more than 200 railroad mergers between 1838 and 1982. It was headquartered in Roanoke, for most of its existence, its motto was "Precision Transportation". During the Civil War, the N&W was the biggest railroad in the south and moved most of the products with their steam locomotives to help the South the best way they could; the N&W was famous for manufacturing its own steam locomotives, which were built at the Roanoke Shops, as well as its own hopper cars. In 1960, N&W became the last major class 1 railroad to end steam but didn't retire its last remaining Y class 2-8-8-2s until 1964 and 1965. By 1965, steam on class I railroads was gone but steam wasn't gone on class II railroads until 1974 and class III and mining railroads did not retire their steam locomotives from their active roster until 1983. By 1983, steam in America on class I, II, III, mining railroads had closed the chapter on America's 150 years of steam from 1830 - 1983.
In December 1959, the N&W merged with the Virginian Railway, a longtime rival in the Pocahontas coal region. By 1970, other mergers with the Nickel Plate Road and Wabash formed a system that operated 7,595 miles of road on 14,881 miles of track from North Carolina to New York and from Virginia to Iowa. In 1980, the N&W teamed with the Southern Railway, another profitable carrier and created the Norfolk Southern Corporation holding company by merging its business operations with the business operations of the Southern Railway; the N&W and the Southern Railway continued as separate railroads now under one holding company. On June 1, 1982, the Southern Railway was renamed "Norfolk Southern Railway" to reflect the Norfolk Southern Corporation and on the same day, the renamed Norfolk Southern Railway gained full control of the Norfolk and Western Railway with the Norfolk and Western being transferred from the holding company to the renamed Norfolk Southern Railway, this began the final years of Norfolk and Western, absorbed into the renamed Norfolk Southern Railway seven years in 1997.
In 1997 during the Conrail battle with CSX, Norfolk Southern Corporation's principal railroad, the renamed Norfolk Southern Railway, absorbed the Norfolk and Western Railway into their rail system, ending the existence of the Norfolk and Western Railway and having the renamed Norfolk Southern Railway becoming the only railroad in the entire Norfolk Southern system after that. The N&W's earliest predecessor was the City Point Railroad, a 9-mile short-line railroad formed in 1838 to extend from City Point, a port on the tidal James River, to Petersburg, Virginia, on the fall line of the shallower Appomattox River. In 1854, CPRR became part of the South Side Railroad, which connected Petersburg with Lynchburg, where it interchanged through traffic with the Virginia and Tennessee Railroad and the James River and Kanawha Canal. William Mahone, an 1847 engineering graduate of the Virginia Military Institute, was employed by Francis Mallory to build the Norfolk and Petersburg Railroad and became its president in the pre-Civil War era.
Construction of N&P began in 1853. Mahone's innovative corduroy roadbed through the Great Dismal Swamp near Norfolk, employed a log foundation laid at right angles beneath the surface of the swamp, it is still in use 150 years and it withstands immense tonnages of coal traffic. Mahone married Otelia Butler, from Smithfield in Isle of Wight County, Virginia, a daughter of Robert Butler, a Virginia state treasurer. Popular legend has it that Otelia and William Mahone traveled along the newly completed N&P naming stations along the 52-mile tangent between Suffolk and Petersburg from Ivanhoe, a book she was reading by Walter Scott. From Scott's historical Scottish novels, Otelia chose the place names of Windsor and Wakefield, she tapped the Scottish Clan "McIvor" for the name of a small Southampton County town. When they could not agree, it is said that the young couple invented a new word in honor of their "dispute", how the tiny community of Disputanta was named; the N&P was completed in 1858. Of small stature, dynamic "Little Billy" Mahone became a major general in the Confederate Army during the American Civil War.
He was regarded as the hero of the Battle of the Crater during the Siege of Petersburg in 1864–65. Otelia Mahone served as a nurse in the Confederate capital of Richmond; the N&P was severed by the war. The portion east of the Blackwater River at Zuni, was held by the Union for most of the war; the eastern portion of the City Point Railroad played a crucial role for Union General Ulysses S. Grant during the Siege of Petersburg, was operated by the United States Military Railroad; the South Side Railroad was heavily damaged. William and Otelia Mahone were illustrious characters in post-bellum Virginia. Mahone got to work restoring "his" N&P, resumed his dream of linking the three trunk lines across the southern tier of Virginia to reach points to the west, he became president of all three, drove the 1870 merger of N&P, South Side Railroad and the Virginia and Tennessee Railroad to form the Atlantic and Ohio Railroad. The AM&O extended 408 miles from Norfolk to Virginia; the Mahones moved to the headquarters city of Lynchburg, the midpoint of the AM&O.
The acronym AM&O was said to stand for "All Mine a
The Appalachian Mountains called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed 480 million years ago during the Ordovician Period, they once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion. The Appalachian chain is a barrier to east–west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west. Definitions vary on the precise boundaries of the Appalachians; the United States Geological Survey defines the Appalachian Highlands physiographic division as consisting of thirteen provinces: the Atlantic Coast Uplands, Eastern Newfoundland Atlantic, Maritime Acadian Highlands, Maritime Plain, Notre Dame and Mégantic Mountains, Western Newfoundland Mountains, Blue Ridge and Ridge, Saint Lawrence Valley, Appalachian Plateaus, New England province, the Adirondack areas. A common variant definition does not include the Adirondack Mountains, which geologically belong to the Grenville Orogeny and have a different geological history from the rest of the Appalachians.
The mountain range is in the United States but it extends into southeastern Canada, forming a zone from 100 to 300 mi wide, running from the island of Newfoundland 1,500 mi southwestward to Central Alabama in the United States. The range covers parts of the islands of Saint Pierre and Miquelon, which comprise an overseas territory of France; the system is divided into a series of ranges, with the individual mountains averaging around 3,000 ft. The highest of the group is Mount Mitchell in North Carolina at 6,684 feet, the highest point in the United States east of the Mississippi River; the term Appalachian refers to several different regions associated with the mountain range. Most broadly, it refers to the entire mountain range with its surrounding hills and the dissected plateau region; the term is used more restrictively to refer to regions in the central and southern Appalachian Mountains including areas in the states of Kentucky, Virginia, West Virginia, North Carolina, as well as sometimes extending as far south as northern Alabama and western South Carolina, as far north as Pennsylvania, southern Ohio, parts of southern upstate New York.
The Ouachita Mountains in Arkansas and Oklahoma were part of the Appalachians as well but became disconnected through geologic history. While exploring inland along the northern coast of Florida in 1528, the members of the Narváez expedition, including Álvar Núñez Cabeza de Vaca, found a Native American village near present-day Tallahassee, Florida whose name they transcribed as Apalchen or Apalachen; the name was soon altered by the Spanish to Apalachee and used as a name for the tribe and region spreading well inland to the north. Pánfilo de Narváez's expedition first entered Apalachee territory on June 15, 1528, applied the name. Now spelled "Appalachian," it is the fourth-oldest surviving European place-name in the US. After the de Soto expedition in 1540, Spanish cartographers began to apply the name of the tribe to the mountains themselves; the first cartographic appearance of Apalchen is on Diego Gutierrez's map of 1562. The name was not used for the whole mountain range until the late 19th century.
A competing and more popular name was the "Allegheny Mountains", "Alleghenies", "Alleghania". In the early 19th century, Washington Irving proposed renaming the United States either Appalachia or Alleghania. In U. S. dialects in the southern regions of the Appalachians, the word is pronounced, with the third syllable sounding like "latch". In northern parts of the mountain range, it is pronounced or. There is great debate between the residents of the regions as to which pronunciation is the more correct one. Elsewhere, a accepted pronunciation for the adjective Appalachian is, with the last two syllables "-ian" pronounced as in the word "Romanian"; the whole system may be divided into three great sections: Northern: The northern section runs from the Canadian province of Newfoundland and Labrador to the Hudson River. It includes the Long Range Mountains and Annieopsquotch Mountains on the island of Newfoundland, Chic-Choc Mountains and Notre Dame Range in Quebec and New Brunswick, scattered elevations and small ranges elsewhere in Nova Scotia and New Brunswick, the Longfellow Mountains in Maine, the White Mountains in New Hampshire, the Green Mountains in Vermont, The Berkshires in Massachusetts and Connecticut.
The Metacomet Ridge Mountains in Connecticut and south-central Massachusetts, although contained within the Appalachian province, is a younger system and not geologically associated with the Appalachians. The Monteregian Hills, which cross the Green Mountains in Quebec, are unassociated with the Appalachians. Central: The central section goes from the Hudson Valley to the New River running through Virginia and West Virginia, it comprises the Valley Ridges between the Allegheny Front of the Allegheny Plateau and the Great Appalachian Valley, the New York–New Jersey Highlands, the Taconic Mountains in New York, a large portion of the Blue Ridge. Southern: The southern section runs from the New River onwards, it consists of the prolongation of the Blue Ridge, divided into the Western Blue Ridge Front and the Eastern Blue Ridge Front, the Ridge-and-Valley Appalachians, the Cumberland Plateau. The Adirondack Mountains in New Y
Iron is a chemical element with symbol Fe and atomic number 26. It is a metal, that belongs to group 8 of the periodic table, it is by mass the most common element on Earth, forming much of Earth's inner core. It is the fourth most common element in the Earth's crust. Pure iron is rare on the Earth's crust being limited to meteorites. Iron ores are quite abundant, but extracting usable metal from them requires kilns or furnaces capable of reaching 1500 °C or higher, about 500 °C higher than what is enough to smelt copper. Humans started to dominate that process in Eurasia only about 2000 BCE, iron began to displace copper alloys for tools and weapons, in some regions, only around 1200 BCE; that event is considered the transition from the Bronze Age to the Iron Age. Iron alloys, such as steel and special steels are now by far the most common industrial metals, because of their mechanical properties and their low cost. Pristine and smooth pure iron surfaces are mirror-like silvery-gray. However, iron reacts with oxygen and water to give brown to black hydrated iron oxides known as rust.
Unlike the oxides of some other metals, that form passivating layers, rust occupies more volume than the metal and thus flakes off, exposing fresh surfaces for corrosion. The body of an adult human contains about 3 to 5 grams of elemental iron in hemoglobin and myoglobin; these two proteins play essential roles in vertebrate metabolism oxygen transport by blood and oxygen storage in muscles. To maintain the necessary levels, human iron metabolism requires a minimum of iron in the diet. Iron is the metal at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals. Chemically, the most common oxidation states of iron are +2 and +3. Iron shares many properties of other transition metals, including the other group 8 elements and osmium. Iron forms compounds in a wide range of oxidation states, −2 to +7. Iron forms many coordination compounds. At least four allotropes of iron are known, conventionally denoted α, γ, δ, ε; the first three forms are observed at ordinary pressures.
As molten iron cools past its freezing point of 1538 °C, it crystallizes into its δ allotrope, which has a body-centered cubic crystal structure. As it cools further to 1394 °C, it changes to its γ-iron allotrope, a face-centered cubic crystal structure, or austenite. At 912 °C and below, the crystal structure again becomes the bcc α-iron allotrope; the physical properties of iron at high pressures and temperatures have been studied extensively, because of their relevance to theories about the cores of the Earth and other planets. Above 10 GPa and temperatures of a few hundred kelvin or less, α-iron changes into another hexagonal close-packed structure, known as ε-iron; the higher-temperature γ-phase changes into ε-iron, but does so at higher pressure. Some controversial experimental evidence exists for a stable β phase at pressures above 50 GPa and temperatures of at least 1500 K, it is supposed to have a double hcp structure. The inner core of the Earth is presumed to consist of an iron-nickel alloy with ε structure.
The melting and boiling points of iron, along with its enthalpy of atomization, are lower than those of the earlier 3d elements from scandium to chromium, showing the lessened contribution of the 3d electrons to metallic bonding as they are attracted more and more into the inert core by the nucleus. This same trend appears for ruthenium but not osmium; the melting point of iron is experimentally well defined for pressures less than 50 GPa. For greater pressures, published data still varies by tens of gigapascals and over a thousand kelvin. Below its Curie point of 770 °C, α-iron changes from paramagnetic to ferromagnetic: the spins of the two unpaired electrons in each atom align with the spins of its neighbors, creating an overall magnetic field; this happens because the orbitals of those two electrons do not point toward neighboring atoms in the lattice, therefore are not involved in metallic bonding. In the absence of an external source of magnetic field, the atoms get spontaneously partitioned into magnetic domains, about 10 micrometres across, such that the atoms in each domain have parallel spins, but different domains have other orientations.
Thus a macroscopic piece of iron will have a nearly zero overall magnetic field. Application of an external magnetic field causes the domains that are magnetized in the same general direction to grow at the expense of adjacent ones that point in other directions, reinforcing the external field; this effect is exploited in devices that needs to channel magnetic fields, such as electrical transformers, magnetic recording heads, electric motors. Impurities, lattice defects, or grain and particle boundaries can "pin" the domains in the new positions, so that the effect persists after the external field is removed -- thus turning the iron object into a magnet. Similar behavior is exhibited by some iron compounds, such as the fer
Native Americans in the United States
Native Americans known as American Indians, Indigenous Americans and other terms, are the indigenous peoples of the United States, except Hawaii. There are over 500 federally recognized tribes within the US, about half of which are associated with Indian reservations; the term "American Indian" excludes Native Hawaiians and some Alaska Natives, while Native Americans are American Indians, plus Alaska Natives of all ethnicities. Native Hawaiians are not counted as Native Americans by the US Census, instead being included in the Census grouping of "Native Hawaiian and other Pacific Islander"; the ancestors of modern Native Americans arrived in what is now the United States at least 15,000 years ago much earlier, from Asia via Beringia. A vast variety of peoples and cultures subsequently developed. Native Americans were affected by the European colonization of the Americas, which began in 1492, their population declined precipitously due to introduced diseases as well as warfare, territorial confiscation and slavery.
After the founding of the United States, many Native American peoples were subjected to warfare and one-sided treaties, they continued to suffer from discriminatory government policies into the 20th century. Since the 1960s, Native American self-determination movements have resulted in changes to the lives of Native Americans, though there are still many contemporary issues faced by Native Americans. Today, there are over five million Native Americans in the United States, 78% of whom live outside reservations; when the United States was created, established Native American tribes were considered semi-independent nations, as they lived in communities separate from British settlers. The federal government signed treaties at a government-to-government level until the Indian Appropriations Act of 1871 ended recognition of independent native nations, started treating them as "domestic dependent nations" subject to federal law; this law did preserve the rights and privileges agreed to under the treaties, including a large degree of tribal sovereignty.
For this reason, many Native American reservations are still independent of state law and actions of tribal citizens on these reservations are subject only to tribal courts and federal law. The Indian Citizenship Act of 1924 granted U. S. citizenship to all Native Americans born in the United States. This emptied the "Indians not taxed" category established by the United States Constitution, allowed natives to vote in state and federal elections, extended the Fourteenth Amendment protections granted to people "subject to the jurisdiction" of the United States. However, some states continued to deny Native Americans voting rights for several decades. Bill of Rights protections do not apply to tribal governments, except for those mandated by the Indian Civil Rights Act of 1968. Since the end of the 15th century, the migration of Europeans to the Americas has led to centuries of population and agricultural transfer and adjustment between Old and New World societies, a process known as the Columbian exchange.
As most Native American groups had preserved their histories by oral traditions and artwork, the first written sources of the conflict were written by Europeans. Ethnographers classify the indigenous peoples of North America into ten geographical regions with shared cultural traits, called cultural areas; some scholars combine the Plateau and Great Basin regions into the Intermontane West, some separate Prairie peoples from Great Plains peoples, while some separate Great Lakes tribes from the Northeastern Woodlands. The ten cultural areas are as follows: Arctic, including Aleut and Yupik peoples Subarctic Northeastern Woodlands Southeastern Woodlands Great Plains Great Basin Northwest Plateau Northwest Coast California Southwest At the time of the first contact, the indigenous cultures were quite different from those of the proto-industrial and Christian immigrants; some Northeastern and Southwestern cultures, in particular, were matrilineal and operated on a more collective basis than that with which Europeans were familiar.
The majority of Indigenous American tribes maintained their hunting grounds and agricultural lands for use of the entire tribe. Europeans at that time had patriarchal cultures and had developed concepts of individual property rights with respect to land that were different; the differences in cultures between the established Native Americans and immigrant Europeans, as well as shifting alliances among different nations in times of war, caused extensive political tension, ethnic violence, social disruption. Before the European settlement of what is now the United States, Native Americans suffered high fatalities from contact with new European diseases, to which they had not yet acquired immunity. Smallpox epidemics are thought to have caused the greatest loss of life for indigenous populations. William M Denevan, noted author and Professor Emeritus of Geography at the University of Wisconsin-Madison, said on this subject in his essay "The Pristine Myth: The Landscape of the Americas in 1492".
Old World diseases were the primary killer. In many regions the tropical lowlands, populations fell by 90 percent or more in the first century after the contact. "Estimates of the pre-Columbian population of what today constitutes the U. S. vary ranging from William M Denevan's 3.8 million in his 1992 w