St. John's, Newfoundland and Labrador
St. John's is the capital and largest city of the Canadian province of Newfoundland and Labrador, it is on the eastern tip of the Avalon Peninsula on Newfoundland. The city is North America's easternmost city, its name has been attributed to the Nativity of John the Baptist, when John Cabot was believed to have sailed into the harbour in 1497 and to a Basque fishing town with the same name. Existing on maps as early as 1519, it is one of the oldest cities in North America, it was incorporated as a city in 1888. With a metropolitan population of 219,207, the St. John's Metropolitan Area is Canada's 20th largest metropolitan area and the second largest Census Metropolitan Area in Atlantic Canada, after Halifax; the city has a rich history, having played a role in the French and Indian War, the American Revolutionary War, the War of 1812. Italian inventor Guglielmo Marconi received the first transatlantic wireless signal in St. John's, its history and culture have made it into an important tourist destination.
St. John's is the oldest post-Columbian European settlement in North America, with fishermen setting up seasonal camps in the early 16th century. Sebastian Cabot declares in a handwritten Latin text in his original 1545 map that St. John's earned its name when he and his father, the Venetian explorer John Cabot became the first Europeans to sail into the harbour, in the morning of 24 June 1494, the feast day of Saint John the Baptist. However, the locations of Cabot's landfalls are disputed. A series of expeditions to St. John's by Portuguese from the Azores took place in the early 16th century, by 1540 French and Portuguese ships crossed the Atlantic annually to fish the waters off the Avalon Peninsula. In the Basque Country, it is a common belief the name of St. John's was given by Basque fishermen because the bay of St. John's is similar to the Bay of Pasaia in the Basque Country, where one of the fishing towns is called St. John; the earliest record of the location appears as São João on a Portuguese map by Pedro Reinel in 1519.
When John Rut visited St. John's in 1527, he found Norman and Portuguese ships in the harbour. On 3 August 1527, Rut wrote a letter to King Henry on the findings of his voyage to North America. St. Jehan is shown on Nicolas Desliens' world map of 1541, San Joham is found in João Freire's Atlas of 1546. On 5 August 1583, an English Sea Dog, Sir Humphrey Gilbert, claimed the area as England's first overseas colony under Royal Charter of Queen Elizabeth I. There was no permanent population and Gilbert was lost at sea during his return voyage, thereby ending any immediate plans for settlement; the Newfoundland National War Memorial is on the waterfront in St. John's, at the purported site of Gilbert's landing and proclamation. By 1620, the fishermen of England's West Country controlled most of Newfoundland's east coast. In 1627, William Payne, called St. John's "the principal prime and chief lot in all the whole country". Sometime after 1630, the town of St. John's was established as a permanent community.
Before this they were expressly forbidden by the English government, at the urging of the West Country fishing industry, from establishing permanent settlements along the English-controlled coast. The population grew in the 17th century: St. John's was Newfoundland's largest settlement when English naval officers began to take censuses around 1675; the population grew in the summers with the arrival of migratory fishermen. In 1680, fishing ships set up fishing rooms at St. John's, bringing hundreds of Irish men into the port to operate inshore fishing boats; the town's first significant defenses were erected due to commercial interests, following the temporary seizure of St. John's by the Dutch admiral Michiel de Ruyter in June 1665; the inhabitants fended off a second Dutch attack in 1673, when it was defended by Christopher Martin, an English merchant captain. Martin landed six cannons from his vessel, the Elias Andrews, constructed an earthen breastwork and battery near Chain Rock commanding the Narrows leading into the harbour.
With only 23 men, the valiant Martin beat off an attack by three Dutch warships. The English government planned to expand these fortifications in around 1689, but construction didn't begin until after the French admiral Pierre Le Moyne d'Iberville captured and destroyed the town in the Avalon Peninsula Campaign; when 1500 English reinforcements arrived in late 1697, they found rubble where the town and fortifications had stood. The French attacked St. John's again in 1705, captured it in 1708, devastating civilian structures with fire on each instance; the harbour remained fortified through most of the 19th centuries. The final battle of the Seven Years' War in North America was fought in St. John's. Following a surprise capture of the town by the French early in the year, the British responded and, at the Battle of Signal Hill, the French surrendered St. John's to British forces under the command of Colonel William Amherst. In the late 1700s Fort Amherst and Fort Waldegrave were built to defend the harbour entrance.
There has been some controversy regarding. As mentioned above, while English fishermen had set up seasonal camps in St. John's in the 16th century, they were expressly forbidden by the English government, at the urging of the West Country fishing industry, from establishing permanent s
José Fioravanti was a prolific Argentine sculptor known for the many civic monuments he created. Fioravanti was born in Buenos Aires in 1896, he developed a early interest in sculpture, learned the art in the city's numerous private ateliers. The self-taught sculptor first exhibited in 1912 at that year's National Salon, winning the First Prize in his category during the 1919 National Salon for his work, My Sister María, his work during the next several years consisted of Realist portrait busts created by casting, notably that of former President José Figueroa Alcorta for its placement over the latter's La Recoleta Cemetery crypt. He traveled in Europe from 1924 to 1927 and adopted the method of direct carving, without the use of maquettes. Fioravanti exhibited at the Museum of Modern Art, in the Luxembourg Museum, in Paris, he secured two solo exhibitions in Buenos Aires, including a 1928 Friend of the Arts event inaugurated by President Marcelo Torcuato de Alvear, who commissioned Fioravanti to create decorative reliefs for the Casa Rosada's interiors.
Fioravanti returned to Paris in 1929. He earned increasing renown in the French capital, in 1934 was honored with a solo exhibition at the Galerie nationale du Jeu de Paume. Returning to Argentina in 1935, Fioravanti was appointed Professor at the College of Fine Arts, his portrait of his wife, painter Ludmilla Feodorovna, earned him a gold medal at the 1936 National Salon. Establishing an atelier in seaside La Lucila del Mar, he created numerous landmark monuments in the ensuing years, including memorials in Buenos Aires to Presidents Nicolás Avellaneda and Roque Sáenz Peña, Venezuelan General Simón Bolívar, U. S. President Franklin Roosevelt, as well as two sea lion effigies guarding an esplanade in Mar del Plata, a memorial in Montevideo to Uruguayan General Fructuoso Rivera, to General Manuel Savio, father of the Argentine steel industry, in Villa María, Córdoba. Another significant series of Fioravanti's work would adorn the National Flag Memorial, a landmark overlooking the Paraná River in the city of Rosario.
The memorial, built between 1947 and 1957, would feature Fioravanti's monument to Manuel Belgrano and five allegorical sculptures. It would be the second significant collaboration with Alfredo Bigatti, who created the allegories representing the Four Freedoms for the Roosevelt memorial. Fioravanti died in 1977, in Buenos Aires
An obelisk is a tall, four-sided, narrow tapering monument which ends in a pyramid-like shape or pyramidion at the top. These were called tekhenu by their builders, the Ancient Egyptians; the Greeks who saw them used the Greek term'obeliskos' to describe them, this word passed into Latin and English. Ancient obelisks are monolithic. Most modern obelisks are made of several stones; the term stele is used for other monumental, upright and sculpted stones. Obelisks played a vital role in their religion and were prominent in the architecture of the ancient Egyptians, who placed them in pairs at the entrance of the temples; the word "obelisk" as used in English today is of Greek rather than Egyptian origin because Herodotus, the Greek traveller, was one of the first classical writers to describe the objects. A number of ancient Egyptian obelisks are known to have survived, plus the "Unfinished Obelisk" found hewn from its quarry at Aswan; these obelisks are now dispersed around the world, fewer than half of them remain in Egypt.
The earliest temple obelisk still in its original position is the 68-foot 120-metric-ton red granite Obelisk of Senusret I of the XIIth Dynasty at Al-Matariyyah in modern Heliopolis. The obelisk symbolized the sun god Ra, during the religious reformation of Akhenaten it was said to have been a petrified ray of the Aten, the sundisk, it was thought that the god existed within the structure. Benben was the mound that arose from the primordial waters Nu upon which the creator god Atum settled in the creation story of the Heliopolitan creation myth form of Ancient Egyptian religion; the Benben stone is the top stone of the Egyptian pyramid. It is related to the Obelisk, it is hypothesized by New York University Egyptologist Patricia Blackwell Gary and Astronomy senior editor Richard Talcott that the shapes of the ancient Egyptian pyramid and obelisk were derived from natural phenomena associated with the sun. The pyramid and obelisk's significance have been overlooked the astronomical phenomena connected with sunrise and sunset: the zodiacal light and sun pillars respectively.
Around 30 B. C. after Cleopatra "the last Pharaoh" committed suicide, Rome took control of Egypt. The Ancient Romans were awestruck by the obelisks, looted the complex to the extent that they destroyed walls at the Temple of Karnak to haul out obelisks. There are now more than twice as many obelisks that were seized and shipped out by Rome as remain in Egypt. A majority were dismantled during the Roman period over 1, 700 years ago and the obelisk were sent in different locations; the largest standing and tallest Egyptian obelisk is the Lateran Obelisk in the square at the west side of the Lateran Basilica in Rome at 105.6 feet tall and a weight of 455 metric tons. Not all the Egyptian obelisks in the Roman Empire were set up at Rome. Herod the Great imitated his Roman patrons and set up a red granite Egyptian obelisk in the hippodrome of his new city Caesarea in northern Judea; this one weighs about 100 metric tons. It has been re-erected at its former site. In 335 A. D. Constantine I ordered the removal of two of Karnak's obelisks.
One was sent to Constantinople, the Eastern Emperor Theodosius took the obelisk and had it set up in a hippodrome, where it has weathered Crusaders and Seljuks and stands in the Hippodrome square, now called Istanbul. This one stood 95 feet tall and weighing 380 metric tons, its lower half reputedly once stood in Istanbul but is now lost. The Istanbul obelisk is 65 feet tall; the other was transported to Rome and is the most well-known 25 metres, 331-metric-ton obelisk at Saint Peter's Square in the world. The obelisk had stood since AD 37 on its site and on the wall of the Circus of Nero, flanking St Peter's Basilica: "The elder Pliny in his Natural History refers to the obelisk's transportation from Egypt to Rome by order of the Emperor Gaius as an outstanding event; the barge that carried it had a huge mast of fir wood. One hundred and twenty bushels of lentils were needed for ballast. Having fulfilled its purpose, the gigantic vessel was no longer wanted. Therefore, filled with stones and cement, it was sunk to form the foundations of the foremost quay of the new harbour at Ostia."Re-erecting the obelisk had daunted Michelangelo, but Sixtus V was determined to erect it in front of St Peter's, of which the nave was yet to be built.
He had a full-sized wooden mock-up erected within months of his election. Domenico Fontana, the assistant of Giacomo Della Porta in the Basilica's construction, presented the Pope with a little model crane of wood and a heavy little obelisk of lead, which Sixtus himself was able to raise by turning a little winch with his finger. Fontana was given the project; the obelisk, half-buried in the debris of the ages, was first excavated. The re-erection, scheduled for 14 September, the Feast of the Exaltation of the Cross, was watched by a large crowd, it was a famous feat of engineering, which made the reputation of Fontana, who detailed it in a book illustrated with copperplate etchings, Della Trasportatione dell'Obelisco Vaticano et delle Fabriche di Nostro Sig
Buenos Aires is the capital and largest city of Argentina. The city is located on the western shore of the estuary of the Río de la Plata, on the South American continent's southeastern coast. "Buenos Aires" can be translated as "fair winds" or "good airs", but the former was the meaning intended by the founders in the 16th century, by the use of the original name "Real de Nuestra Señora Santa María del Buen Ayre". The Greater Buenos Aires conurbation, which includes several Buenos Aires Province districts, constitutes the fourth-most populous metropolitan area in the Americas, with a population of around 15.6 million. The city of Buenos Aires is the Province's capital. In 1880, after decades of political infighting, Buenos Aires was federalized and removed from Buenos Aires Province; the city limits were enlarged to include the towns of Flores. The 1994 constitutional amendment granted the city autonomy, hence its formal name: Autonomous City of Buenos Aires, its citizens first elected a chief of government in 1996.
Buenos Aires is considered an'alpha city' by the study GaWC5. Buenos Aires' quality of life was ranked 91st in the world, being one of the best in Latin America in 2018, it is the most visited city in South America, the second-most visited city of Latin America. Buenos Aires is a top tourist destination, is known for its preserved Eclectic European architecture and rich cultural life. Buenos Aires held the 1st Pan American Games in 1951 as well as hosting two venues in the 1978 FIFA World Cup. Buenos Aires hosted the 2018 the 2018 G20 summit. Buenos Aires is a multicultural city, being home to multiple religious groups. Several languages are spoken in the city in addition to Spanish, contributing to its culture and the dialect spoken in the city and in some other parts of the country; this is because in the last 150 years the city, the country in general, has been a major recipient of millions of immigrants from all over the world, making it a melting pot where several ethnic groups live together and being considered one of the most diverse cities of the Americas.
It is recorded under the archives of Aragonese that Catalan missionaries and Jesuits arriving in Cagliari under the Crown of Aragon, after its capture from the Pisans in 1324 established their headquarters on top of a hill that overlooked the city. The hill was known to them as Bonaira, as it was free of the foul smell prevalent in the old city, adjacent to swampland. During the siege of Cagliari, the Catalans built a sanctuary to the Virgin Mary on top of the hill. In 1335, King Alfonso the Gentle donated the church to the Mercedarians, who built an abbey that stands to this day. In the years after that, a story circulated, claiming that a statue of the Virgin Mary was retrieved from the sea after it miraculously helped to calm a storm in the Mediterranean Sea; the statue was placed in the abbey. Spanish sailors Andalusians, venerated this image and invoked the "Fair Winds" to aid them in their navigation and prevent shipwrecks. A sanctuary to the Virgin of Buen Ayre would be erected in Seville.
In the first foundation of Buenos Aires, Spanish sailors arrived thankfully in the Río de la Plata by the blessings of the "Santa Maria de los Buenos Aires", the "Holy Virgin Mary of the Good Winds", said to have given them the good winds to reach the coast of what is today the modern city of Buenos Aires. Pedro de Mendoza called the city "Holy Mary of the Fair Winds", a name suggested by the chaplain of Mendoza's expedition – a devotee of the Virgin of Buen Ayre – after the Sardinian Madonna de Bonaria. Mendoza's settlement soon came under attack by indigenous people, was abandoned in 1541. For many years, the name was attributed to a Sancho del Campo, said to have exclaimed: How fair are the winds of this land!, as he arrived. But Eduardo Madero, in 1882 after conducting extensive research in Spanish archives concluded that the name was indeed linked with the devotion of the sailors to Our Lady of Buen Ayre. A second settlement was established in 1580 by Juan de Garay, who sailed down the Paraná River from Asunción.
Garay preserved the name chosen by Mendoza, calling the city Ciudad de la Santísima Trinidad y Puerto de Santa María del Buen Aire. The short form "Buenos Aires" became the common usage during the 17th century; the usual abbreviation for Buenos Aires in Spanish is Bs. As, it is common as well to refer to it as "B. A." or "BA". While "BA" is used more by expats residing in the city, the locals more use the abbreviation "Baires", in one word. Seaman Juan Díaz de Solís, navigating in the name of Spain, was the first European to reach the Río de la Plata in 1516, his expedition was cut short when he was killed during an attack by the native Charrúa tribe in what is now Uruguay. The city of Buenos Aires was first established as Ciudad de Nuestra Señora Santa María del Buen Ayre after Our Lady of Bonaria on 2 February 1536 by a Spanish expedition led by Pedro de Mendoza; the settlement founded by Mendoza was located in what is today the San Telmo district of Buenos Aires, south of the city centre. More attacks by the indigenous
Perth is the capital and largest city of the Australian state of Western Australia. It is named after the city of Perth, Scotland and is the fourth-most populous city in Australia, with a population of 2.04 million living in Greater Perth. Perth is part of the South West Land Division of Western Australia, with the majority of the metropolitan area located on the Swan Coastal Plain, a narrow strip between the Indian Ocean and the Darling Scarp; the first areas settled were on the Swan River at Guildford, with the city's central business district and port both founded downriver. Perth was founded by Captain James Stirling in 1829 as the administrative centre of the Swan River Colony, it gained city status in 1856 and was promoted to the status of a Lord Mayorality in 1929. The city inherited its name due to the influence of Sir George Murray Member of Parliament for Perthshire and Secretary of State for War and the Colonies; the city's population increased as a result of the Western Australian gold rushes in the late 19th century.
During Australia's involvement in World War II, Fremantle served as a base for submarines operating in the Pacific Theatre, a US Navy Catalina flying boat fleet was based at Matilda Bay. An influx of immigrants after the war, predominantly from Britain, Greece and Yugoslavia, led to rapid population growth; this was followed by a surge in economic activity flowing from several mining booms in the late 20th and early 21st centuries that saw Perth become the regional headquarters for several large mining operations located around the state. As part of Perth's role as the capital of Western Australia, the state's Parliament and Supreme Court are located within the city, as is Government House, the residence of the Governor of Western Australia. Perth came seventh in the Economist Intelligence Unit's August 2016 list of the world's most liveable cities and was classified by the Globalization and World Cities Research Network in 2010 as a Beta world city; the city hosted the 1962 Commonwealth Games.
Perth is divided into 30 local government areas and 250 suburbs, stretching from Two Rocks in the north to Singleton in the south, east inland to The Lakes. Outside of the main CBD, important urban centres within Perth include Joondalup. Most of those were established as separate settlements and retained a distinct identity after being subsumed into the wider metropolitan area. Mandurah, Western Australia's second-largest city, has in recent years formed a conurbation with Perth along the coast, though for most purposes it is still considered a separate city. Indigenous Australians have inhabited the Perth area for at least 38,000 years, as evidenced by archaeological remains at Upper Swan; the Noongar people lived as hunter-gatherers. The wetlands on the Swan Coastal Plain were important to them, both spiritually and as a source of food; the Noongar people know the area. Boorloo formed part of the territory of the Mooro, a Noongar clan, which at the time of British settlement had Yellagonga as their leader.
The Mooro was one of several Noongar Indigenous clans based around the Swan River known collectively as the Whadjuk. The Whadjuk themselves were one of a larger group of fourteen tribes that formed the south-west socio-linguistic block known as the Noongar sometimes called the Bibbulmun. On 19 September 2006, the Federal Court of Australia brought down a judgment recognising Noongar native title over the Perth metropolitan area in the case of Bennell v State of Western Australia FCA 1243; the judgment was overturned on appeal. The first documented sighting of the region was made by the Dutch Captain Willem de Vlamingh and his crew on 10 January 1697. Subsequent sightings between this date and 1829 were made by other Europeans, but as in the case of the sighting and observations made by Vlamingh, the area was considered to be inhospitable and unsuitable for the agriculture that would be needed to sustain a settlement. Although the Colony of New South Wales had established a convict-supported settlement at King George's Sound on the south coast of Western Australia in 1826 in response to rumours that the area would be annexed by France, Perth was the first full-scale settlement by Europeans in the western third of the continent.
The British colony would be designated Western Australia in 1832 but was known informally for many years as the Swan River Colony after the area's major watercourse. On 4 June 1829, newly arriving British colonists had their first view of the mainland, Western Australia's founding has since been recognised by a public holiday on the first Monday in June each year. Captain James Stirling, aboard Parmelia, said that Perth was "as beautiful as anything of this kind I had witnessed". On 12 August that year, Helen Dance, wife of the captain of the second ship, cut down a tree to mark the founding of the town, it is clear that Stirling had selected the name Perth for the capital well before the town was proclaimed, as his proclamation of the colony, read in Fremantle on 18 June 1829, ended "given under my hand and Seal at Perth this 18th Day of June 1829. James Stirling Lieutenant Governor"; the only contemporary information on the source of the name comes from Fremantle's diary entry for 12 August, which records that they "named the town Perth according to the wishes of Sir George Murray".
Murray was born in Perth and was in 1829 Secretary of State for the Colonies and Member for Perthshire in the British House of Commons. The town was named after the Scottish Pert
Victoria, British Columbia
Victoria is the capital city of the Canadian province of British Columbia, located on the southern tip of Vancouver Island off Canada's Pacific coast. The city has a population of 85,792, while the metropolitan area of Greater Victoria has a population of 367,770, making it the 15th most populous Canadian metropolitan area. Victoria is the 7th most densely populated city in Canada with 4,405.8 people per square kilometre, a greater population density than Toronto. Victoria is the southernmost major city in Western Canada, is about 100 kilometres from British Columbia's largest city of Vancouver on the mainland; the city is about 100 km from Seattle by airplane, ferry, or the Victoria Clipper passenger-only ferry which operates daily, year round between Seattle and Victoria, 40 kilometres from Port Angeles, Washington, by ferry Coho across the Strait of Juan de Fuca. Named after Queen Victoria of the United Kingdom and, at the time, British North America, Victoria is one of the oldest cities in the Pacific Northwest, with British settlement beginning in 1843.
The city has retained a large number of its historic buildings, in particular its two most famous landmarks, Parliament Buildings and the Empress hotel. The city's Chinatown is the second oldest in North America after San Francisco's; the region's Coast Salish First Nations peoples established communities in the area long before non-native settlement several thousand years earlier, which had large populations at the time of European exploration. Known as "The Garden City", Victoria is an attractive city and a popular tourism destination with a thriving technology sector that has risen to be its largest revenue-generating private industry. Victoria is according to Numbeo; the city has a large non-local student population, who come to attend the University of Victoria, Camosun College, Royal Roads University, the Victoria College of Art, the Canadian College of Performing Arts, high school programs run by the region's three school districts. Victoria is popular with boaters with its rugged beaches.
Victoria is popular with retirees, who come to enjoy the temperate and snow-free climate of the area as well as the relaxed pace of the city. Prior to the arrival of European navigators in the late 1700s, the Victoria area was home to several communities of Coast Salish peoples, including the Songhees; the Spanish and British took up the exploration of the northwest coast, beginning with the visits of Juan Pérez in 1774, of James Cook in 1778. Although the Victoria area of the Strait of Juan de Fuca was not penetrated until 1790, Spanish sailors visited Esquimalt Harbour in 1790, 1791, 1792. In 1841 James Douglas was charged with the duty of setting up a trading post on the southern tip of Vancouver Island, upon the recommendation by George Simpson a new more northerly post be built in case Fort Vancouver fell into American hands. Douglas founded Fort Victoria on the site of present-day Victoria in anticipation of the outcome of the Oregon Treaty in 1846, extending the British North America/United States border along the 49th parallel from the Rockies to the Strait of Georgia.
Erected in 1843 as a Hudson's Bay Company trading post on a site called Camosun known as "Fort Albert", the settlement was renamed Fort Victoria in November 1843, in honour of Queen Victoria. The Songhees established a village across the harbour from the fort; the Songhees' village was moved north of Esquimalt. The crown colony was established in 1849. Between the years 1850-1854 a series of treaty agreements known as the Douglas Treaties were made with indigenous communities to purchase certain plots of land in exchange for goods; these agreements contributed to a town being laid out on the site and made the capital of the colony, though controversy has followed about the ethical negotiation and upholding of rights by the colonial government. The superintendent of the fort, Chief Factor James Douglas was made the second governor of the Vancouver Island Colony, would be the leading figure in the early development of the city until his retirement in 1864; when news of the discovery of gold on the British Columbia mainland reached San Francisco in 1858, Victoria became the port, supply base, outfitting centre for miners on their way to the Fraser Canyon gold fields, mushrooming from a population of 300 to over 5000 within a few days.
Victoria was incorporated as a city in 1862. In 1865, the North Pacific home of the Royal Navy was established in Esquimalt and today is Canada's Pacific coast naval base. In 1866 when the island was politically united with the mainland, Victoria was designated the capital of the new united colony instead of New Westminster – an unpopular move on the Mainland – and became the provincial capital when British Columbia joined the Canadian Confederation in 1871. In the latter half of the 19th century, the Port of Victoria became one of North America's largest importers of opium, serving the opium trade from Hong Kong and distribution into North America. Opium trade was legal and unregulated until 1865 the legislature issued licences and levied duties on its import and sale; the opium trade was banned in 1908. In 1886, with the completion of the Canadian Pacific Railway terminus on Burrard Inlet, Victoria's position as the commercial centre of British Columbia was irrevocably lost to the city of Vancouver, British Columbia.
The city subsequently began culti
Sandstone is a clastic sedimentary rock composed of sand-sized mineral particles or rock fragments. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to weathering processes at the Earth's surface, as seen in Bowen's reaction series. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds form visible cliffs and other topographic features, certain colors of sandstone have been identified with certain regions. Rock formations that are composed of sandstone allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine-grained aquifers, such as sandstones, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity. Quartz-bearing sandstone can be changed into quartzite through metamorphism related to tectonic compression within orogenic belts.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals; the cements binding these grains together are calcite and silica. Grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. Clays and sediments with smaller grain sizes not visible with the naked eye, including siltstones and shales, are called argillaceous sediments; the formation of sandstone involves two principal stages. First, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Sedimentation occurs by the sand settling out from suspension. Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains; the most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried.
Colors will be tan or yellow. A predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe and Mongolia; the regularity of the latter favours use as a source for masonry, either as a primary building material or as a facing stone, over other forms of construction. The environment where it is deposited is crucial in determining the characteristics of the resulting sandstone, which, in finer detail, include its grain size and composition and, in more general detail, include the rock geometry and sedimentary structures. Principal environments of deposition may be split between terrestrial and marine, as illustrated by the following broad groupings: Terrestrial environmentsRivers Alluvial fans Glacial outwash Lakes Deserts Marine environmentsDeltas Beach and shoreface sands Tidal flats Offshore bars and sand waves Storm deposits Turbidites Framework grains are sand-sized detrital fragments that make up the bulk of a sandstone.
These grains can be classified into several different categories based on their mineral composition: Quartz framework grains are the dominant minerals in most clastic sedimentary rocks. These physical properties allow the quartz grains to survive multiple recycling events, while allowing the grains to display some degree of rounding. Quartz grains evolve from plutonic rock, which are felsic in origin and from older sandstones that have been recycled. Feldspathic framework grains are the second most abundant mineral in sandstones. Feldspar can be divided into two smaller subdivisions: plagioclase feldspars; the different types of feldspar can be distinguished under a petrographic microscope. Below is a description of the different types of feldspar. Alkali feldspar is a group of minerals in which the chemical composition of the mineral can range from KAlSi3O8 to NaAlSi3O8, this represents a complete solid solution. Plagioclase feldspar is a complex group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8.
Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, called lithic fragments or clasts. Lithic fragments can be any fine-grained or coarse-grained igneous, metamorphic, or sedimentary rock, although the most common lithic fragments found in sedimentary rocks are clasts of volcanic rocks. Accessory minerals are all other mineral grains in a sandstone. Common accessory minerals include micas, olivine and corundum. Many of these accessory grains are more dense than the silicates that