Reform Act 1832
The Representation of the People Act 1832 was an Act of Parliament of the United Kingdom that introduced wide-ranging changes to the electoral system of England and Wales. According to its preamble, the Act was designed to "take effectual Measures for correcting divers Abuses that have long prevailed in the Choice of Members to serve in the Commons House of Parliament". Before the reform, most members nominally represented boroughs; the number of electors in a borough varied from a dozen or so up to 12,000. The selection of MPs was controlled by one powerful patron: for example Charles Howard, 11th Duke of Norfolk, controlled eleven boroughs. Criteria for qualification for the franchise varied among boroughs, from the requirement to own land, to living in a house with a hearth sufficient to boil a pot. There had been calls for reform long without success; the Act that succeeded was proposed by the Whigs, led by Prime Minister Charles Grey, 2nd Earl Grey. It met with significant opposition from the Pittite factions in Parliament, who had long governed the country.
The bill was passed as a result of public pressure. The Act granted seats in the House of Commons to large cities that had sprung up during the Industrial Revolution, removed seats from the "rotten boroughs": those with small electorates and dominated by a wealthy patron; the Act increased the electorate from about 400,000 to 650,000, making about one in five adult males eligible to vote. The full title is An Act to amend the representation of the people in Wales, its formal short title and citation is "Representation of the People Act 1832". The Act applied only in Wales; the separate Scottish Reform Act 1832 was revolutionary, enlarging the electorate by a factor of 1300% from 5000 to 65,000. After the Acts of Union 1800 became law on 1 January 1801, the unreformed House of Commons was composed of 658 members, of whom 513 represented England and Wales. There were two types of constituencies. County members were supposed to represent landholders, while borough members were supposed to represent the mercantile and trading interests of the kingdom.
Counties were historical national subdivisions established between the 16th centuries. They were not parliamentary constituencies; the members of Parliament chosen by the counties were known as Knights of the Shire. In Wales each county elected one member, while in England each county elected two members until 1826, when Yorkshire's representation was increased to four, following the disenfranchisement of the Cornish borough of Grampound. Parliamentary boroughs in England ranged in size from small hamlets to large cities because they had evolved haphazardly; the earliest boroughs were chosen in the Middle Ages by county sheriffs, a village might be deemed a borough. Many of these early boroughs were substantial settlements at the time of their original enfranchisement, but went into decline, by the early 19th century some only had a few electors, but still elected two MPs. In centuries the reigning monarch decided which settlements to enfranchise; the monarchs seem to have done so capriciously with little regard for the merits of the place they were enfranchising.
Of the 70 English boroughs that Tudor monarchs enfranchised, 31 were disenfranchised. The parliamentarians of the 17th century compounded the inconsistencies by re-enfranchising 15 boroughs whose representation had lapsed for centuries, seven of which were disenfranchised by the Reform Act. After Newark was enfranchised in 1661, no additional boroughs were enfranchised, the unfair system remained unchanged until the Reform Act of 1832. Grampound's disenfranchisement in 1821 was the sole exception. Most English boroughs elected two MPs; the City of London and the joint borough of Weymouth and Melcombe Regis each elected four members. The Welsh boroughs each returned a single member. Statutes passed in 1430 and 1432, during the reign of Henry VI, standardised property qualifications for county voters. Under these Acts, all owners of freehold property or land worth at least forty shillings in a particular county were entitled to vote in that county; this requirement, known as the forty shilling freehold, was never adjusted for inflation.
The franchise was restricted to males by custom rather than statute. The vast majority of people were not entitled to vote. Furthermore, the sizes of the individual county constituencies varied significantly; the smallest counties and Anglesey, had fewer than 1,000 voters each, while the largest county, had more than 20,000. Those who owned property in multiple constituencies could vote multiple times. In boroughs the franchise was far more varied. There were broadly six types of parliamenta
Clifton Down is an area of public open space in Bristol, north of the village of Clifton. With its neighbour Durdham Down to the northeast, it constitutes the large area known as The Downs, much used for leisure including walking and team sports. Clifton Down is the part of the Downs south of Stoke Road. There is an Iron Age hill fort at Clifton Camp on Observatory Hill on the down, there are remnants of an Iron Age or Roman field system between Ladies Mile and Bristol Zoo; the Roman road from Bath to Sea Mills crossed the Downs near Stoke Road, a short length is visible as a raised grassy bank. In the Middle Ages Clifton Down was the commons of pasture for the manor of Clifton. In 1676 and 1686 the manor of Clifton was purchased by the Society of Merchant Venturers. During the 18th century Clifton became a fashionable summer spa, Clifton Down was used for recreation. There were lead mines in the 18th century, which account for the bumpy surface in the area by Upper Belgrave Road known as the Dumps.
A gibbet was erected opposite the top end of Gallows Acre Lane. By the mid-19th century Clifton Down ceased to be used for grazing. Clifton became a desirable place to live, large houses were built close to Clifton Down. Bristol Corporation became concerned at the threat to this public amenity, in 1861 promoted an Act of Parliament, under which the Society of Merchant Venturers undertook to secure Clifton Down for public enjoyment free of charge. Since 1861 Clifton Down has been managed, with Durdham Down, by the Downs Committee, a joint committee of the Society of Merchant Venturers and Bristol City Council, which owns Durdham Down; the committee appoints a Downs Ranger to oversee the Downs. On 20 September 1908 there was a meeting across the road near the water tower to support the Suffragette movement: some 10,000 people were there. Stone cairns were placed on all open spaces to deter landings of enemy aircraft: the cairns were removed in 1944. In May 1941, 32 acres were requisitioned on the east side of Ladies Mile to store military vehicles in six canvas hangars.
There was a tank repair area near the Sea Walls. An area of 42 acres to the west of Ladies Mile was used from February 1944 to store heavy army equipment; the downs and Durdham, are separated by the busy commuter road of Stoke Road, passing the prominent'concrete elephant' water tower and adjoining tea room. At right angles to Stoke Road runs the dead straight'Ladies Mile', to the South West corner of the Downs and Bridge Valley Road. In Victorian and Edwardian times this was a promenading and horse-riding spot for the affluent, similar to Rotten Row in London. After the Great War, it now on a more commercial basis. From the southwest corner of Clifton Down, in an area known as the Sea Wall, there are panoramic views of the Avon Gorge and the Clifton Suspension Bridge. Near Clifton village is the site of a small tower with a camera obscura at the top. Located close to the observatory is an open face of rock, used as a slide by generations of Bristolians and students; this "rock slide" is now an attraction to visitors.
A railway tunnel, Clifton Down Tunnel, passes underneath Clifton on the line from Temple Meads to Severn Beach. One portal is in Clifton near Clifton Down railway station. There are three air shafts for the tunnel: two in vertical tower form with the third being a horizontal tunnel on the Portway. Part of Clifton Down is used by gay men as a cruising ground. In 2008, there were concerns by some gay men at the removal of vegetation as part of the Avon Gorge Management Plan, on the grounds that this was discrimination on the grounds of sexual orientation. Victoria Hughes, lavatory attendant at Stoke Road and autobiographer. Map of Clifton Down circa 1900
The Ionic order forms one of the three classical orders of classical architecture, the other two canonic orders being the Doric and the Corinthian. There are two lesser orders: the Tuscan, the rich variant of Corinthian called the composite order, both added by 16th-century Italian architectural writers, based on Roman practice. Of the three canonic orders, the Ionic order has the narrowest columns; the Ionic capital is characterized by the use of volutes. The Ionic columns stand on a base which separates the shaft of the column from the stylobate or platform. Since Vitruvius, a female character has been ascribed to the Ionic; the major features of the Ionic order are the volutes of its capital, which have been the subject of much theoretical and practical discourse, based on a brief and obscure passage in Vitruvius. The only tools required to design these features were a straight-edge, a right angle, string and a compass. Below the volutes, the Ionic column may have a wide collar or banding separating the capital from the fluted shaft, or a swag of fruit and flowers may swing from the clefts or "neck" formed by the volutes.
The volutes lay in a single plane. This feature of the Ionic order made it more pliant and satisfactory than the Doric to critical eyes in the 4th century BC: angling the volutes on the corner columns ensured that they "read" when seen from either front or side facade; the 16th-century Renaissance architect and theorist Vincenzo Scamozzi designed a version of such a four-sided Ionic capital. The Ionic column is always more slender than the Doric. Ionic columns are most fluted. After a little early experimentation, the number of hollow flutes in the shaft settled at 24; this standardization kept the fluting in a familiar proportion to the diameter of the column at any scale when the height of the column was exaggerated. Roman fluting leaves a little of the column surface between each hollow. In some instances, the fluting has been omitted. English architect Inigo Jones introduced a note of sobriety with plain Ionic columns on his Banqueting House at Whitehall Palace and when Beaux-Arts architect John Russell Pope wanted to convey the manly stamina combined with intellect of Theodore Roosevelt, he left colossal Ionic columns unfluted on the Roosevelt memorial at the American Museum of Natural History, New York City, for an unusual impression of strength and stature.
Wabash Railroad architect R. E. Mohr included 8 unfluted Ionic frontal columns on his 1928 design for the railroad's St. Louis suburban stop Delmar Station; the entablature resting on the columns has three parts: a plain architrave divided into two, or more three, with a frieze resting on it that may be richly sculptural, a cornice built up with dentils, with a corona and cyma molding to support the projecting roof. Pictorial narrative bas-relief frieze carving provides a characteristic feature of the Ionic order, in the area where the Doric order is articulated with triglyphs. Roman and Renaissance practice condensed the height of the entablature by reducing the proportions of the architrave, which made the frieze more prominent; the Ionic anta capital is the ionic version of the anta capital, the crowning portion of an anta, the front edge of a supporting wall in Greek temple architecture. The anta is crowned by a stone block designed to spread the load from superstructure it supports, called an "anta capital" when it is structural, or sometimes "pilaster capital" if it is only decorative as during the Roman period.
In order not to protrude unduly from the wall, these anta capitals display a rather flat surface, so that the capital has more or less a rectangular-shaped structure overall. The ionic anta capital, in contrast to the regular column capitals, is decorated and includes bands of alternating lotuses and flame palmettes, bands of eggs and darts and beads and reels patterns, in order to maintain continuity with the decorative frieze lining the top of the walls; this difference with the column capitals disappeared with Roman times, when anta or pilaster capitals have designs similar to those of the column capitals. The ionic anta capitals as can be seen in the Ionic-order temple of the Erechtheion, are characteristically rectangular Ionic anta capitals, with extensive bands of floral patterns in prolongation of adjoining friezes; the Ionic order originated in the mid-6th century BC in Ionia, the southwestern coastland and islands of Asia Minor settled by Ionian Greeks, where an Ionian dialect was spoken.
The Ionic order column was being practiced in mainland Greece in the 5th century BC. It was most popular in the Archaic Period in Ionia; the first of the great Ionic temples was the Temple of Hera on Samos, built about 570–560 BC by the architect Rhoikos. It stood for only a decade. A longer-lasting 6th century Ionic temple was the Temple of Artemis at Ephesus, one of t
Wiltshire is a county in South West England with an area of 3,485 km2. It is landlocked and borders the counties of Dorset, Hampshire, Gloucestershire and Berkshire; the county town was Wilton, after which the county is named, but Wiltshire Council is now based in the county town of Trowbridge. Wiltshire is characterised by its high wide valleys. Salisbury Plain is noted for being the location of the Stonehenge and Avebury stone circles and other ancient landmarks, as a training area for the British Army; the city of Salisbury is notable for its medieval cathedral. Important country houses open to the public include Longleat, near Warminster, the National Trust's Stourhead, near Mere; the county, in the 9th century written as Wiltunscir Wiltonshire, is named after the former county town of Wilton. Wiltshire is notable for its pre-Roman archaeology; the Mesolithic and Bronze Age people that occupied southern Britain built settlements on the hills and downland that cover Wiltshire. Stonehenge and Avebury are the most famous Neolithic sites in the UK.
In the 6th and 7th centuries Wiltshire was at the western edge of Saxon Britain, as Cranborne Chase and the Somerset Levels prevented the advance to the west. The Battle of Bedwyn was fought in 675 between Escuin, a West Saxon nobleman who had seized the throne of Queen Saxburga, King Wulfhere of Mercia. In 878 the Danes invaded the county. Following the Norman Conquest, large areas of the country came into the possession of the crown and the church. At the time of the Domesday Survey the industry of Wiltshire was agricultural. In the succeeding centuries sheep-farming was vigorously pursued, the Cistercian monastery of Stanley exported wool to the Florentine and Flemish markets in the 13th and 14th centuries. In the 17th century English Civil War Wiltshire was Parliamentarian; the Battle of Roundway Down, a Royalist victory, was fought near Devizes. In 1794 it was decided at a meeting at the Bear Inn in Devizes to raise a body of ten independent troops of Yeomanry for the county of Wiltshire, which formed the basis for what would become the Royal Wiltshire Yeomanry, who served with distinction both at home and abroad, during the Boer War, World War I and World War II.
The Royal Wiltshire Yeomanry lives on as Y Squadron, based in Swindon, B Squadron, based in Salisbury, of the Royal Wessex Yeomanry. Around 1800 the Kennet and Avon Canal was built through Wiltshire, providing a route for transporting cargoes from Bristol to London until the development of the Great Western Railway. Information on the 261 civil parishes of Wiltshire is available on Wiltshire Council's Wiltshire Community History website which has maps, demographic data and modern pictures and short histories; the local nickname for Wiltshire natives is "Moonrakers". This originated from a story of smugglers who managed to foil the local Excise men by hiding their alcohol French brandy in barrels or kegs, in a village pond; when confronted by the excise men they raked the surface to conceal the submerged contraband with ripples, claimed that they were trying to rake in a large round cheese visible in the pond a reflection of the full moon. The officials took them for simple yokels or mad and left them alone, allowing them to continue with their illegal activities.
Many villages claim the tale for their own village pond, but the story is most linked with The Crammer in Devizes. Two-thirds of Wiltshire, a rural county, lies on chalk, a kind of soft, porous limestone, resistant to erosion, giving it a high chalk downland landscape; this chalk is part of a system of chalk downlands throughout eastern and southern England formed by the rocks of the Chalk Group and stretching from the Dorset Downs in the west to Dover in the east. The largest area of chalk in Wiltshire is Salisbury Plain, used for arable agriculture and by the British Army as training ranges; the highest point in the county is the Tan Hill–Milk Hill ridge in the Pewsey Vale, just to the north of Salisbury Plain, at 295 m above sea level. The chalk uplands run northeast into West Berkshire in the Marlborough Downs ridge, southwest into Dorset as Cranborne Chase. Cranborne Chase, which straddles the border, like Salisbury Plain, yielded much Stone Age and Bronze Age archaeology; the Marlborough Downs are part of a 1,730 km2 conservation area.
In the northwest of the county, on the border with South Gloucestershire and Bath and North East Somerset, the underlying rock is the resistant oolite limestone of the Cotswolds. Part of the Cotswolds AONB is in Wiltshire, in the county's northwestern corner. Between the areas of chalk and limestone downland are clay vales; the largest of these vales is the Avon Vale. The Avon cuts diagonally through the north of the county, flowing through Bradford-on-Avon and into Bath and Bristol; the Vale of Pewsey has been cut through the chalk into Greensand and Oxford Clay in the centre of the county. In the south west of the county is the Vale of Wardour; the southeast of the county lies on the sandy soils of the northernmost area of the New Forest. Chalk is a porous rock, so the chalk hills have little surface water; the main settlements in the county are therefore situated at wet points. Notably, Salisbury is situated between the chalk of marshy flood plains; the county has green belt along its western fringes as a part of the extensive Avon green belt, reaching as far as the outskirts of Rudloe/Corsham and Trowbridge, preventing urban spr
England is a country, part of the United Kingdom. It shares land borders with Wales to Scotland to the north-northwest; the Irish Sea lies west of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east and the English Channel to the south; the country covers five-eighths of the island of Great Britain, which lies in the North Atlantic, includes over 100 smaller islands, such as the Isles of Scilly and the Isle of Wight. The area now called England was first inhabited by modern humans during the Upper Palaeolithic period, but takes its name from the Angles, a Germanic tribe deriving its name from the Anglia peninsula, who settled during the 5th and 6th centuries. England became a unified state in the 10th century, since the Age of Discovery, which began during the 15th century, has had a significant cultural and legal impact on the wider world; the English language, the Anglican Church, English law – the basis for the common law legal systems of many other countries around the world – developed in England, the country's parliamentary system of government has been adopted by other nations.
The Industrial Revolution began in 18th-century England, transforming its society into the world's first industrialised nation. England's terrain is chiefly low hills and plains in central and southern England. However, there is upland and mountainous terrain in the west; the capital is London, which has the largest metropolitan area in both the United Kingdom and the European Union. England's population of over 55 million comprises 84% of the population of the United Kingdom concentrated around London, the South East, conurbations in the Midlands, the North West, the North East, Yorkshire, which each developed as major industrial regions during the 19th century; the Kingdom of England – which after 1535 included Wales – ceased being a separate sovereign state on 1 May 1707, when the Acts of Union put into effect the terms agreed in the Treaty of Union the previous year, resulting in a political union with the Kingdom of Scotland to create the Kingdom of Great Britain. In 1801, Great Britain was united with the Kingdom of Ireland to become the United Kingdom of Great Britain and Ireland.
In 1922 the Irish Free State seceded from the United Kingdom, leading to the latter being renamed the United Kingdom of Great Britain and Northern Ireland. The name "England" is derived from the Old English name Englaland, which means "land of the Angles"; the Angles were one of the Germanic tribes that settled in Great Britain during the Early Middle Ages. The Angles came from the Anglia peninsula in the Bay of Kiel area of the Baltic Sea; the earliest recorded use of the term, as "Engla londe", is in the late-ninth-century translation into Old English of Bede's Ecclesiastical History of the English People. The term was used in a different sense to the modern one, meaning "the land inhabited by the English", it included English people in what is now south-east Scotland but was part of the English kingdom of Northumbria; the Anglo-Saxon Chronicle recorded that the Domesday Book of 1086 covered the whole of England, meaning the English kingdom, but a few years the Chronicle stated that King Malcolm III went "out of Scotlande into Lothian in Englaland", thus using it in the more ancient sense.
According to the Oxford English Dictionary, its modern spelling was first used in 1538. The earliest attested reference to the Angles occurs in the 1st-century work by Tacitus, Germania, in which the Latin word Anglii is used; the etymology of the tribal name itself is disputed by scholars. How and why a term derived from the name of a tribe, less significant than others, such as the Saxons, came to be used for the entire country and its people is not known, but it seems this is related to the custom of calling the Germanic people in Britain Angli Saxones or English Saxons to distinguish them from continental Saxons of Old Saxony between the Weser and Eider rivers in Northern Germany. In Scottish Gaelic, another language which developed on the island of Great Britain, the Saxon tribe gave their name to the word for England. An alternative name for England is Albion; the name Albion referred to the entire island of Great Britain. The nominally earliest record of the name appears in the Aristotelian Corpus the 4th-century BC De Mundo: "Beyond the Pillars of Hercules is the ocean that flows round the earth.
In it are two large islands called Britannia. But modern scholarly consensus ascribes De Mundo not to Aristotle but to Pseudo-Aristotle, i.e. it was written in the Graeco-Roman period or afterwards. The word Albion or insula Albionum has two possible origins, it either derives from a cognate of the Latin albus meaning white, a reference to the white cliffs of Dover or from the phrase the "island of the Albiones" in the now lost Massaliote Periplus, attested through Avienus' Ora Maritima to which the former served as a source. Albion is now applied to England in a more poetic capacity. Another romantic name for England is Loegria, related to the Welsh word for England and made popular by its use in Arthurian legend; the earliest known evidence of human presence in the area now known as England was that of Homo antecessor, dating to approximate
A portico is a porch leading to the entrance of a building, or extended as a colonnade, with a roof structure over a walkway, supported by columns or enclosed by walls. This idea was used in ancient Greece and has influenced many cultures, including most Western cultures; some noteworthy examples of porticos are the East Portico of the United States Capitol, the portico adorning the Pantheon in Rome and the portico of University College London. Porticos are sometimes topped with pediments. Palladio was a pioneer of using temple-fronts for secular buildings. In the UK, the temple-front applied to The Vyne, was the first portico applied to an English country house. A pronaos is the inner area of the portico of a Greek or Roman temple, situated between the portico's colonnade or walls and the entrance to the cella, or shrine. Roman temples had an open pronaos with only columns and no walls, the pronaos could be as long as the cella; the word pronaos is Greek for "before a temple". In Latin, a pronaos is referred to as an anticum or prodomus.
The different variants of porticos are named by the number of columns. The "style" suffix comes from the Greek στῦλος, "column"; the tetrastyle has four columns. The Romans favoured the four columned portico for their pseudoperipteral temples like the Temple of Portunus, for amphiprostyle temples such as the Temple of Venus and Roma, for the prostyle entrance porticos of large public buildings like the Basilica of Maxentius and Constantine. Roman provincial capitals manifested tetrastyle construction, such as the Capitoline Temple in Volubilis; the North Portico of the White House is the most notable four-columned portico in the United States. Hexastyle buildings had six columns and were the standard façade in canonical Greek Doric architecture between the archaic period 600–550 BCE up to the Age of Pericles 450–430 BCE; some well-known examples of classical Doric hexastyle Greek temples: The group at Paestum comprising the Temple of Hera, the Temple of Apollo, the first Temple of Athena and the second Temple of Hera The Temple of Athena Aphaia at Aegina c. 495 BCE Temple E at Selinus dedicated to Hera The Temple of Zeus at Olympia, now a ruin Temple F or the so-called "Temple of Concord" at Agrigentum, one of the best-preserved classical Greek temples, retaining all of its peristyle and entablature.
The "unfinished temple" at Segesta The Hephaesteum below the Acropolis at Athens, long known as the "Theseum" one of the most intact Greek temples surviving from antiquity The Temple of Poseidon on Cape Sunium Hexastyle was applied to Ionic temples, such as the prostyle porch of the sanctuary of Athena on the Erechtheum, at the Acropolis of Athens. With the colonization by the Greeks of Southern Italy, hexastyle was adopted by the Etruscans and subsequently acquired by the ancient Romans. Roman taste favoured narrow pseudoperipteral and amphiprostyle buildings with tall columns, raised on podiums for the added pomp and grandeur conferred by considerable height; the Maison Carrée at Nîmes, France, is the best-preserved Roman hexastyle temple surviving from antiquity. Octastyle buildings had eight columns; the best-known octastyle buildings surviving from antiquity are the Parthenon in Athens, built during the Age of Pericles, the Pantheon in Rome. The destroyed Temple of Divus Augustus in Rome, the centre of the Augustan cult, is shown on Roman coins of the 2nd century CE as having been built in octastyle.
The decastyle has ten columns. The only known Roman decastyle portico is on the Temple of Venus and Roma, built by Hadrian in about 130 CE. Classical architecture List of classical architecture terms Hypostyle Loggia Stoa Porte-cochere "Greek architecture". Encyclopædia Britannica. 1968. Stierlin, Henri. Editor-in-chief Angelika Taschen, ed. Greece: From Mycenae to the Parthenon. Cologne: TASCHEN. ISBN 3-8228-1225-0. CS1 maint: Extra text: editors list Stierlin, Henri. Silvia Kinkle, ed; the Roman Empire: From the Etruscans to the Decline of the Roman Empire. Cologne: TASCHEN. ISBN 3-8228-1778-3
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