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131-476: The Haytor Granite Tramway (also called Heytor) was a tramway built to convey granite from Haytor Down, Dartmoor , Devon to the Stover Canal . It was very unusual in that the track was formed of granite sections, shaped to guide the wheels of horse-drawn wagons . It was built in 1820; the granite was in demand in the developing cities of England as masonry to construct public buildings and bridges. In 1850

262-501: A business improvement district . The abutments of modern London Bridge rest several metres above natural embankments of gravel, sand and clay. From the late Neolithic era the southern embankment formed a natural causeway above the surrounding swamp and marsh of the river's estuary ; the northern ascended to higher ground at the present site of Cornhill . Between the embankments, the River Thames could have been crossed by ford when

393-498: A pontoon type bridge at the site during the conquest period (AD   43). A bridge of any kind would have given a rapid overland shortcut to Camulodunum from the southern and Kentish ports, along the Roman roads of Stane Street and Watling Street (now the A2 ). The Roman roads leading to and from London were probably built around AD   50, and the river-crossing was possibly served by

524-562: A 'cross building' above the roadway, linking the houses either side and extending from the first floor upwards. All the houses were shops, and the bridge was one of the City of London's four or five main shopping streets. There seems to have been a deliberate attempt to attract the more prestigious trades. In the late fourteenth century more than four-fifths of the shopkeepers were haberdashers , glovers, cutlers , bowyers and fletchers or from related trades. By 1600 all of these had dwindled except

655-435: A Dutchman, Peter Morris, created a waterworks at the north end of the bridge. Water wheels under the two northernmost arches drove pumps that raised water to the top of a tower, from which wooden pipes conveyed it into the city. In 1591 water wheels were installed at the south end of the bridge to grind corn. In 1633 fire destroyed the houses on the northern part of the bridge. The gap was only partly filled by new houses, with

786-553: A basaltic magma to a granitic magma, but the quantities produced are small. For example, granitic rock makes up just 4% of the exposures in the South Sandwich Islands . In continental arc settings, granitic rocks are the most common plutonic rocks, and batholiths composed of these rock types extend the entire length of the arc. There are no indication of magma chambers where basaltic magmas differentiate into granites, or of cumulates produced by mafic crystals settling out of

917-563: A crane should be built and new interchange sidings made at the 'Bovey Granite Siding', 1-mile (1.6 km) south of Bovey Tracey, although it was probably never used. A mile of the old tramway route had been taken over for the new line. The 1831 map of Devonshire by Fisher, Son & Co. depicts the course of the tramway and erroneously shows it running directly down to the Teign without the Stover canal being in existence. A map of Devon of about 1865 shows

1048-520: A diapir it would expend far too much energy in heating wall rocks, thus cooling and solidifying before reaching higher levels within the crust. Fracture propagation is the mechanism preferred by many geologists as it largely eliminates the major problems of moving a huge mass of magma through cold brittle crust. Magma rises instead in small channels along self-propagating dykes which form along new or pre-existing fracture or fault systems and networks of active shear zones. As these narrow conduits open,

1179-433: A flock of sheep across the bridge, supposedly by ancient right. On 3 June 2017, three pedestrians were killed by a van in a terrorist attack . Altogether, eight people died and 48 were injured in the attack. Security barriers were installed on the bridge to help isolate the pedestrian pavement from the road. The nearest London Underground stations are Monument , at the northern end of the bridge, and London Bridge at

1310-610: A granite that is derived from partial melting of metasedimentary rocks may have more alkali feldspar, whereas a granite derived from partial melting of metaigneous rocks may be richer in plagioclase. It is on this basis that the modern "alphabet" classification schemes are based. The letter-based Chappell & White classification system was proposed initially to divide granites into I-type (igneous source) granite and S-type (sedimentary sources). Both types are produced by partial melting of crustal rocks, either metaigneous rocks or metasedimentary rocks. I-type granites are characterized by

1441-565: A high content of sodium and calcium, and by a strontium isotope ratio, Sr/ Sr, of less than 0.708. Sr is produced by radioactive decay of Rb, and since rubidium is concentrated in the crust relative to the mantle, a low ratio suggests origin in the mantle. The elevated sodium and calcium favor crystallization of hornblende rather than biotite. I-type granites are known for their porphyry copper deposits. I-type granites are orogenic (associated with mountain building) and usually metaluminous. S-type granites are sodium-poor and aluminum-rich. As

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1572-508: A later legend that London Bridge was built on wool packs . In 1202, before Colechurch's death, Isembert, a French monk who was renowned as a bridge builder, was appointed by King John to complete the project. Construction was not finished until 1209. There were houses on the bridge from the start; this was a normal way of paying for the maintenance of a bridge, though in this case it had to be supplemented by other rents and by tolls. From 1282 two bridge wardens were responsible for maintaining

1703-423: A mainline running down to the Stover canal and six branches or sidings running from the separate quarries. The sidings were altered several times during the existence of the line and track was often lifted and used elsewhere as circumstances demanded. Various minor and one substantial cutting, small embankments and a few short bridges exist along the length of the line. Owing to the nature of the 'rails' large parts of

1834-820: A much higher proportion of clay with the Cecil soil series a prime example of the consequent Ultisol great soil group. Granite is a natural source of radiation , like most natural stones. Potassium-40 is a radioactive isotope of weak emission, and a constituent of alkali feldspar , which in turn is a common component of granitic rocks, more abundant in alkali feldspar granite and syenites . Some granites contain around 10 to 20 parts per million (ppm) of uranium . By contrast, more mafic rocks, such as tonalite, gabbro and diorite , have 1 to 5 ppm uranium, and limestones and sedimentary rocks usually have equally low amounts. Many large granite plutons are sources for palaeochannel -hosted or roll front uranium ore deposits , where

1965-649: A new stone bridge in place of the old, with a chapel at its centre dedicated to Becket as martyr . The archbishop had been a native Londoner, born at Cheapside , and a popular figure. The Chapel of St Thomas on the Bridge became the official start of pilgrimage to his Canterbury shrine ; it was grander than some town parish churches, and had an additional river-level entrance for fishermen and ferrymen. Building work began in 1176, supervised by Peter of Colechurch. The costs would have been enormous; Henry's attempt to meet them with taxes on wool and sheepskins probably gave rise to

2096-572: A new, purpose-built hollow core steel-reinforced concrete structure, ensuring the bridge would support the weight of modern traffic. The bridge was reconstructed by Sundt Construction at Lake Havasu City, Arizona , and was re-dedicated on 10 October 1971 in a ceremony attended by London's Lord Mayor and celebrities. The bridge carries the McCulloch Boulevard and spans the Bridgewater Channel, an artificial, navigable waterway that leads from

2227-536: A peculiar mineralogy and geochemistry, with particularly high silicon and potassium at the expense of calcium and magnesium and a high content of high field strength cations (cations with a small radius and high electrical charge, such as zirconium , niobium , tantalum , and rare earth elements .) They are not orogenic, forming instead over hot spots and continental rifting, and are metaluminous to mildly peralkaline and iron-rich. These granites are produced by partial melting of refractory lithology such as granulites in

2358-467: A permanent timber bridge. On the relatively high, dry ground at the northern end of the bridge, a small, opportunistic trading and shipping settlement took root and grew into the town of Londinium . A smaller settlement developed at the southern end of the bridge, in the area now known as Southwark . The bridge may have been destroyed along with the town in the Boudican revolt (AD 60), but Londinium

2489-568: A range of hills, formed by the metamorphic aureole or hornfels . Granite often occurs as relatively small, less than 100 km stock masses ( stocks ) and in batholiths that are often associated with orogenic mountain ranges. Small dikes of granitic composition called aplites are often associated with the margins of granitic intrusions . In some locations, very coarse-grained pegmatite masses occur with granite. Granite forms from silica-rich ( felsic ) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of

2620-415: A result, they contain micas such as biotite and muscovite instead of hornblende. Their strontium isotope ratio is typically greater than 0.708, suggesting a crustal origin. They also commonly contain xenoliths of metamorphosed sedimentary rock, and host tin ores. Their magmas are water-rich, and they readily solidify as the water outgasses from the magma at lower pressure, so they less commonly make it to

2751-525: A single iron arch span of 600 feet (180 m), with 65 feet (20 m) centre clearance beneath it for masted river traffic. His design was accepted as safe and practicable, following expert testimony. Preliminary surveys and works were begun, but Telford's design required exceptionally wide approaches and the extensive use of multiple, steeply inclined planes, which would have required the purchase and demolition of valuable adjacent properties. A more conventional design of five stone arches, by John Rennie ,

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2882-553: A single wider span, the Great Arch, in 1759. Demolition of the houses was completed in 1761 and the last tenant departed after some 550 years of housing on the bridge. Under the supervision of Dance the Elder, the roadway was widened to 46 feet (14 m) and a balustrade was added "in the Gothic taste" together with 14 stone alcoves for pedestrians to shelter in. However, the creation of

3013-463: A wheelbase of 10 ft (3.05 m). The wheels were 2 ft ( 610 mm ) in diameter with a 3-inch (76 mm) tread, and were loose on the axles. The twelve-wheeled reference in the poem above means 'twelve waggons with wheels'. Stover House itself, then the home of the Templer family, had been constructed of Haytor granite in 1781. Granite's popularity as a building material was increasing and

3144-425: A wooden drawbridge. Above and below the water-level, the piers were enclosed and protected by ' starlings ', supported by deeper piles than the piers themselves. The bridge, including the part occupied by houses, was from 20 to 24 feet (6.1 to 7.3 metres) wide. The roadway was mostly around 15 feet (4.6 metres) wide, varying from about 14 feet to 16 feet, except that it was narrower at defensive features (the stone gate,

3275-466: Is grus , which is often made up of coarse-grained fragments of disintegrated granite. Climatic variations also influence the weathering rate of granites. For about two thousand years, the relief engravings on Cleopatra's Needle obelisk had survived the arid conditions of its origin before its transfer to London. Within two hundred years, the red granite has drastically deteriorated in the damp and polluted air there. Soil development on granite reflects

3406-539: Is microgranite . The extrusive igneous rock equivalent of granite is rhyolite . Granitic rock is widely distributed throughout the continental crust . Much of it was intruded during the Precambrian age; it is the most abundant basement rock that underlies the relatively thin sedimentary veneer of the continents. Outcrops of granite tend to form tors , domes or bornhardts , and rounded massifs . Granites sometimes occur in circular depressions surrounded by

3537-517: Is 3–6·10 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C (2219–2300 °F); it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present. A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses: The medium-grained equivalent of granite

3668-513: Is also a well-made five-mile (8 km) marker stone. The granite track sections can be followed through the woods before the pathway diverts back onto the main Bovey Tracey road. The tramway cuts across fields down to the road which runs beside the Edgemoor Hotel and a few track setts lie scattered on the lawn of this hotel, but no clear line of the track can be distinguished. Chapple Bridge was

3799-410: Is an excess of aluminum beyond what can be taken up in feldspars (Al 2 O 3 > CaO + K 2 O + Na 2 O) are described as peraluminous , and they contain aluminum-rich minerals such as muscovite . The average density of granite is between 2.65 and 2.75 g/cm (165 and 172 lb/cu ft), its compressive strength usually lies above 200 MPa (29,000 psi), and its viscosity near STP

3930-618: Is believed to have a mass of around 81 tonnes. It was the tallest temple in south India. Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of Elba and Giglio . Granite became "an integral part of the Roman language of monumental architecture". The quarrying ceased around the third century AD. Beginning in Late Antiquity the granite was reused, which since at least

4061-434: Is called a binary or two-mica granite. Two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites, as described below . Another aspect of granite classification is the ratios of metals that potentially form feldspars. Most granites have a composition such that almost all their aluminum and alkali metals (sodium and potassium) are combined as feldspar. This

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4192-604: Is exceedingly unusual, the closest possibly being the Weedon Stoneway in Northamptonshire of 1837 which was built at great expense as a mail coach route by the Turnpike Commissioners who were in competition with the newly constructed London & Birmingham Railway . The only other comparable tramway known to exist was a very short 3 ft gauge limestone line at Conisbrough , near Doncaster . The tramway itself

4323-433: Is limited by the amount of thermal energy available, which must be replenished by crystallization of higher-melting minerals in the magma. Thus, the magma is melting crustal rock at its roof while simultaneously crystallizing at its base. This results in steady contamination with crustal material as the magma rises. This may not be evident in the major and minor element chemistry, since the minerals most likely to crystallize at

4454-404: Is permeated by sheets and channels of light granitic rock (the leucosome ). The leucosome is interpreted as partial melt of a parent rock that has begun to separate from the remaining solid residue (the melanosome). If enough partial melt is produced, it will separate from the source rock, become more highly evolved through fractional crystallization during its ascent toward the surface, and become

4585-454: Is relieved when overlying material is removed by erosion or other processes. Chemical weathering of granite occurs when dilute carbonic acid , and other acids present in rain and soil waters, alter feldspar in a process called hydrolysis . As demonstrated in the following reaction, this causes potassium feldspar to form kaolinite , with potassium ions, bicarbonate, and silica in solution as byproducts. An end product of granite weathering

4716-411: Is some concern that some granite sold as countertops or building material may be hazardous to health. Dan Steck of St. Johns University has stated that approximately 5% of all granite is of concern, with the caveat that only a tiny percentage of the tens of thousands of granite slab types have been tested. Resources from national geological survey organizations are accessible online to assist in assessing

4847-425: Is supported upon twenty piers of square stone, sixty feet high and thirty broad, joined by arches of about twenty feet diameter. The whole is covered on each side with houses so disposed as to have the appearance of a continued street, not at all of a bridge. Upon this is built a tower, on whose top the heads of such as have been executed for high treason are placed on iron spikes: we counted above thirty. The last head

4978-479: Is that magma will rise through the crust as a single mass through buoyancy . As it rises, it heats the wall rocks , causing them to behave as a power-law fluid and thus flow around the intrusion allowing it to pass without major heat loss. This is entirely feasible in the warm, ductile lower crust where rocks are easily deformed, but runs into problems in the upper crust which is far colder and more brittle. Rocks there do not deform so easily: for magma to rise as

5109-410: Is the case when K 2 O + Na 2 O + CaO > Al 2 O 3 > K 2 O + Na 2 O. Such granites are described as normal or metaluminous . Granites in which there is not enough aluminum to combine with all the alkali oxides as feldspar (Al 2 O 3 < K 2 O + Na 2 O) are described as peralkaline , and they contain unusual sodium amphiboles such as riebeckite . Granites in which there

5240-455: Is typically orthoclase or microcline and is often perthitic . The plagioclase is typically sodium-rich oligoclase . Phenocrysts are usually alkali feldspar. Granitic rocks are classified according to the QAPF diagram for coarse grained plutonic rocks and are named according to the percentage of quartz , alkali feldspar ( orthoclase , sanidine , or microcline ) and plagioclase feldspar on

5371-428: Is uncommon, is classified simply as quartz-rich granitoid or, if composed almost entirely of quartz, as quartzolite . True granites are further classified by the percentage of their total feldspar that is alkali feldspar. Granites whose feldspar is 65% to 90% alkali feldspar are syenogranites , while the feldspar in monzogranite is 35% to 65% alkali feldspar. A granite containing both muscovite and biotite micas

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5502-584: The River Thames between the City of London and Southwark in central London since Roman times . The current crossing, which opened to traffic in 1973, is a box girder bridge built from concrete and steel. It replaced a 19th-century stone-arched bridge, which in turn superseded a 600-year-old stone-built medieval structure. In addition to the roadway, for much of its history, the broad medieval bridge supported an extensive built up area of homes and businesses, part of

5633-652: The Roman Empire . With the end of Roman rule in Britain in the early 5th century, Londinium was gradually abandoned and the bridge fell into disrepair. In the Anglo-Saxon period , the river became a boundary between the emergent, mutually hostile kingdoms of Mercia and Wessex . By the late 9th century, Danish invasions prompted at least a partial reoccupation of the site by the Saxons. The bridge may have been rebuilt by Alfred

5764-648: The Trinovantes , who held the region northeast of the Thames Estuary from a capital at Camulodunum , nowadays Colchester in Essex. Claudius imposed a major colonia at Camulodunum, and made it the capital city of the new Roman province of Britannia . The first London Bridge was built by the Romans as part of their road-building programme, to help consolidate their conquest. It is possible that Roman military engineers built

5895-414: The garrets as a storey); three houses had six storeys. Two-thirds of the houses were rebuilt from 1477 to 1548. In the seventeenth century, the usual plan was a shop on the ground floor, a hall and often a chamber on the first floor, a kitchen and usually a chamber and a waterhouse (for hauling up water in buckets) on the second floor, and chambers and garrets above. Approximately every other house shared in

6026-567: The A-Q-P half of the diagram. True granite (according to modern petrologic convention) contains between 20% and 60% quartz by volume, with 35% to 90% of the total feldspar consisting of alkali feldspar . Granitic rocks poorer in quartz are classified as syenites or monzonites , while granitic rocks dominated by plagioclase are classified as granodiorites or tonalites . Granitic rocks with over 90% alkali feldspar are classified as alkali feldspar granites . Granitic rock with more than 60% quartz, which

6157-461: The City from London Bridge Station (south to north). An example of this is actor Hugh Grant crossing the bridge north to south during the morning rush hour, in the 2002 film About a Boy . On 11 July 2008, as part of the annual Lord Mayor 's charity appeal and to mark the 800th anniversary of Old London Bridge's completion in the reign of King John, the Lord Mayor and Freemen of the City drove

6288-524: The City's Bridge ward, and its southern end in Southwark was guarded by a large stone City gateway. The medieval bridge was preceded by a succession of timber bridges, the first of which was built by the Roman founders of London ( Londinium ) around AD 50. The current bridge stands at the western end of the Pool of London and is positioned 30 metres (98 ft) upstream from previous alignments. The approaches to

6419-598: The European Union safety standards (section 4.1.1.1 of the National Health and Engineering study) and radon emission levels well below the average outdoor radon concentrations in the US. Granite and related marble industries are considered one of the oldest industries in the world, existing as far back as Ancient Egypt . Major modern exporters of granite include China, India, Italy, Brazil, Canada, Germany, Sweden, Spain and

6550-665: The Great soon after the Battle of Edington as part of Alfred's redevelopment of the area in his system of burhs , or it may have been rebuilt around 990 under the Saxon king Æthelred the Unready to hasten his troop movements against Sweyn Forkbeard , father of Cnut the Great . A skaldic tradition describes the bridge's destruction in 1014 by Æthelred's ally Olaf , to divide the Danish forces who held both

6681-403: The Great Arch had weakened the rest of the structure and constant expensive repairs were required in the following decades; this, combined with congestion both on and under bridge, often leading to fatal accidents, resulted in public pressure for a modern replacement. In 1799, a competition was opened to design a replacement for the medieval bridge. Entrants included Thomas Telford ; he proposed

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6812-570: The Milestone Society, are detailed below: Granite seems to have been the only traffic carried as the company was reluctant to go to the expense of building high-sided waggons or trucks for iron ore transportation. When the Moretonhampstead and South Devon Railway was opened in 1866, the tramway had been disused since 1858; however the land owner, the Duke of Somerset , insisted that a siding and

6943-631: The Mohs hardness scale) , and tough. These properties have made granite a widespread construction stone throughout human history. The word "granite" comes from the Latin granum , a grain, in reference to the coarse-grained structure of such a completely crystalline rock. Granitic rocks mainly consist of feldspar , quartz , mica , and amphibole minerals , which form an interlocking, somewhat equigranular matrix of feldspar and quartz with scattered darker biotite mica and amphibole (often hornblende ) peppering

7074-504: The United States. The Red Pyramid of Egypt ( c.  2590 BC ), named for the light crimson hue of its exposed limestone surfaces, is the third largest of Egyptian pyramids . Pyramid of Menkaure , likely dating 2510 BC, was constructed of limestone and granite blocks. The Great Pyramid of Giza (c. 2580 BC ) contains a huge granite sarcophagus fashioned of "Red Aswan Granite". The mostly ruined Black Pyramid dating from

7205-486: The Uptown area of Lake Havasu City. The current London Bridge was designed by architect Lord Holford and engineers Mott, Hay and Anderson . It was constructed by contractors John Mowlem and Co from 1967 to 1972, and opened by Queen Elizabeth II on 16 March 1973. It comprises three spans of prestressed-concrete box girders , a total of 833 feet (254 m) long. The cost of £4 million (£71.4 million in 2023),

7336-418: The assemblage in a short and energetic speech, which excited bursts of applause... A later description listed some of the dignitaries who attended: Among the company were Lord and Lady Clifford of Ugbrooke ; Mr. Bastard from Buckland; Sir Thomas Dycke Acland ; Sir Henry Carew came from Haccombe ; and Sir Lawrence Palk from Haldon , beside many other county magnates from other parts. The construction

7467-419: The base of the chamber are the same ones that would crystallize anyway, but crustal assimilation is detectable in isotope ratios. Heat loss to the country rock means that ascent by assimilation is limited to distance similar to the height of the magma chamber. Physical weathering occurs on a large scale in the form of exfoliation joints , which are the result of granite's expanding and fracturing as pressure

7598-418: The big difference in rheology between mafic and felsic magmas makes this process problematic in nature. Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme metasomatism . The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a metamorphic rock into granite. This

7729-518: The bridge itself. The total costs, around £2.5 million (£287 million in 2023), were shared by the British Government and the Corporation of London . Rennie's bridge was 928 feet (283 m) long and 49 feet (15 m) wide, constructed from Haytor granite. The official opening took place on 1 August 1831; King William IV and Queen Adelaide attended a banquet in a pavilion erected on

7860-464: The bridge on the market and began to look for potential buyers. On 18 April 1968, Rennie's bridge was purchased by the Missourian entrepreneur Robert P. McCulloch of McCulloch Oil for US$ 2,460,000. The claim that McCulloch believed mistakenly that he was buying the more impressive Tower Bridge was denied by Luckin in a newspaper interview. Before the bridge was taken apart, each granite facing block

7991-494: The bridge was sinking an inch (about 2.5 cm) every eight years, and by 1924 the east side had sunk some three to four inches (about 9 cm) lower than the west side. The bridge would have to be removed and replaced. Common Council of the City of London member Ivan Luckin put forward the idea of selling the bridge, and recalled: "They all thought I was completely crazy when I suggested we should sell London Bridge when it needed replacing." Subsequently, in 1968, Council placed

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8122-514: The bridge, heading the organization known as the Bridge House. The only two collapses occurred when maintenance had been neglected, in 1281 (five arches) and 1437 (two arches). In 1212, perhaps the greatest of the early fires of London broke out, spreading as far as the chapel and trapping many people. The bridge was about 926 feet (282 metres) long, and had nineteen piers, supported by timber piles. The piers were linked above by nineteen arches and

8253-469: The bridge. The northern approach road, King William Street, was renamed after the monarch and statue of the king subsequently installed. In 1896 the bridge was the busiest point in London, and one of its most congested; 8,000 pedestrians and 900 vehicles crossed every hour. To designs by engineer Edward Cruttwell , it was widened by 13 feet (4.0 m), using granite corbels. Subsequent surveys showed that

8384-436: The business and the tramway fell into neglect, however its robust construction and low recyclable value meant that it was never lifted and much has survived the passage of time. Thomas claims that there were proposals in about 1905 to lay an electric tramway along the route as a tourist attraction, but this scheme failed to mature. The tramway was built in 1820 without an Act of Parliament and opened on 16 September 1820, but

8515-674: The clay traffic, and was extended to Teigngrace in 1820. From here the granite was carried by canal boat to the New Quay at Teignmouth for export by ship, the quay having been built in 1827 for the purpose, making midstream transshipment no longer necessary. In 1829, due to financial difficulties, James Templer's son George Templer (1781–1843) sold Stover House, the Stover Canal and the Haytor Granite Tramway to Edward St Maur, 11th Duke of Somerset (1775–1855), whose family had long owned

8646-563: The construction of bridges on the route of the Templer Waybridge. A previously-unknown section of the tramway at its terminus at Ventiford Basin was discovered in late 2014. 50°35′11″N 3°45′56″W  /  50.58639°N 3.76556°W  / 50.58639; -3.76556 Granite Granite is typical of a larger family of granitic rocks , or granitoids , that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by

8777-437: The consulting engineer is unknown, although George Templer of Stover House owned the quarries and was no doubt responsible. A contemporary description of the official opening shows the extent of the achievement: On Saturday Mr. Templer, of Stover House, gave a grand fete champetre on Haytor Down, on the completion of the granite rail road. The company assembled at its foot on Bovey Heathfield, and in procession passed over it to

8908-534: The course of the line. This is a route which follows closely the route of the Haytor Granite Tramway and the Stover Canal, continuing to the New Quay in Teignmouth docks. A good place to see the track is where it crosses a minor road which leads to Manaton, just off the Haytor to Bovey Tracey road. Once off the moor the place to see the track at its best is a small section of the tramway running through Yarner Wood . There

9039-404: The division between S-type (produced by underplating) and I-type (produced by injection and differentiation) granites, discussed below. The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was. The final texture and composition of a granite are generally distinctive as to its parental rock. For instance,

9170-481: The drawbridge and the drawbridge tower) and wider south of the stone gate. The houses occupied only a few feet on each side of the bridge. They received their main support either from the piers, which extended well beyond the bridge itself from west to east, or from 'hammer beams' laid from pier to pier parallel to the bridge. It was the length of the piers which made it possible to build quite large houses, up to 34 feet (10 metres) deep. The numerous starlings restricted

9301-467: The early 16th century became known as spolia . Through the process of case-hardening , granite becomes harder with age. The technology required to make tempered metal chisels was largely forgotten during the Middle Ages. As a result, Medieval stoneworkers were forced to use saws or emery to shorten ancient columns or hack them into discs. Giorgio Vasari noted in the 16th century that granite in quarries

9432-553: The epic poem The Waste Land by T. S. Eliot . The modern bridge is owned and maintained by Bridge House Estates , an independent charity of medieval origin overseen by the City of London Corporation . It carries the A3 road , which is maintained by the Greater London Authority . The crossing also delineates an area along the southern bank of the River Thames, between London Bridge and Tower Bridge , that has been designated as

9563-579: The first magma to enter solidifies and provides a form of insulation for later magma. These mechanisms can operate in tandem. For example, diapirs may continue to rise through the brittle upper crust through stoping , where the granite cracks the roof rocks, removing blocks of the overlying crust which then sink to the bottom of the diapir while the magma rises to take their place. This can occur as piecemeal stopping (stoping of small blocks of chamber roof), as cauldron subsidence (collapse of large blocks of chamber roof), or as roof foundering (complete collapse of

9694-438: The granite was done by a method known as feather and tare , which had replaced the former 'wedge and groove' method around 1800; this more reliable method being another reason why the use of granite had become practicable. The new method worked by means of a series of holes was made along a potential line of fracture using a tool called a 'jumper'. Feathers were metal prongs with a curved upper end. Two of these were inserted into

9825-684: The grotto is a highly regarded piece of Buddhist art , and along with the temple complex to which it belongs, Seokguram was added to the UNESCO World Heritage List in 1995. Rajaraja Chola I of the Chola Dynasty in South India built the world's first temple entirely of granite in the 11th century AD in Tanjore , India . The Brihadeeswarar Temple dedicated to Lord Shiva was built in 1010. The massive Gopuram (ornate, upper section of shrine)

9956-417: The haberdashers, and the spaces were filled by additional haberdashers, by traders selling textiles and by grocers. From the late seventeenth century there was a greater variety of trades, including metalworkers such as pinmakers and needle makers, sellers of durable goods such as trunks and brushes, booksellers and stationers. The three major buildings on the bridge were the chapel, the drawbridge tower and

10087-525: The holes, the curves in opposite directions at 90 degrees to the line of potential fracture. A wedge-shaped metal tare was hammered between the two until the granite fractured. The granite trade was always somewhat sporadic with fluctuating production and indeed no granite was produced or transported between 1841 and 1851 and the quarries and tramway had closed by 1858. Several thousands of tons of granite had been quarried some years, but competition from Cornish granite quarries with cheaper transport put paid to

10218-570: The lighter color minerals. Occasionally some individual crystals ( phenocrysts ) are larger than the groundmass , in which case the texture is known as porphyritic . A granitic rock with a porphyritic texture is known as a granite porphyry . Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks. Petrographic examination is required for identification of specific types of granitoids. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy . The alkali feldspar in granites

10349-474: The lower crust , rather than by decompression of mantle rock, as is the case with basaltic magmas. It has also been suggested that some granites found at convergent boundaries between tectonic plates , where oceanic crust subducts below continental crust, were formed from sediments subducted with the oceanic plate. The melted sediments would have produced magma intermediate in its silica content, which became further enriched in silica as it rose through

10480-697: The lower continental crust at high thermal gradients. This leads to significant extraction of hydrous felsic melts from granulite-facies resitites. A-type granites occur in the Koettlitz Glacier Alkaline Province in the Royal Society Range, Antarctica. The rhyolites of the Yellowstone Caldera are examples of volcanic equivalents of A-type granite. M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from

10611-435: The magma is inevitable once enough magma has accumulated. However, the question of precisely how such large quantities of magma are able to shove aside country rock to make room for themselves (the room problem ) is still a matter of research. Two main mechanisms are thought to be important: Of these two mechanisms, Stokes diapirism has been favoured for many years in the absence of a reasonable alternative. The basic idea

10742-426: The magma. Other processes must produce these great volumes of felsic magma. One such process is injection of basaltic magma into the lower crust, followed by differentiation, which leaves any cumulates in the mantle. Another is heating of the lower crust by underplating basaltic magma, which produces felsic magma directly from crustal rock. The two processes produce different kinds of granites, which may be reflected in

10873-408: The magmatic parent of granitic rock. The residue of the source rock becomes a granulite . The partial melting of solid rocks requires high temperatures and the addition of water or other volatiles which lower the solidus temperature (temperature at which partial melting commences) of these rocks. It was long debated whether crustal thickening in orogens (mountain belts along convergent boundaries )

11004-405: The mantle. Although the fractional crystallisation of basaltic melts can yield small amounts of granites, which are sometimes found in island arcs, such granites must occur together with large amounts of basaltic rocks. H-type granites were suggested for hybrid granites, which were hypothesized to form by mixing between mafic and felsic from different sources, such as M-type and S-type. However,

11135-478: The medieval bridge were marked by the church of St Magnus-the-Martyr on the northern bank and by Southwark Cathedral on the southern shore. Until Putney Bridge opened in 1729, London Bridge was the only road crossing of the Thames downstream of Kingston upon Thames . London Bridge has been depicted in its several forms, in art, literature, and songs, including the nursery rhyme " London Bridge Is Falling Down ", and

11266-402: The nearby large Berry Pomeroy Castle Estate. George Templer left Devon, only to return a few years later and build a new mansion at Sandford Orleigh on the outskirts of Newton Abbot . He became the granite company's chief Devonshire agent. The wooden flat-topped waggons had iron flangeless wheels and ran in trains of usually twelve waggons drawn by around 18 horses in single file, in front for

11397-420: The old tramway still exist, especially in the area near Haytor itself. Carrington in the late 1820s relates how the rail-road can be used as a route, for pedestrians or those on horseback, from Haytor to Teigngrace, making the point that a tramway usually differs from a railway by effectively being part of a road and also that the frequency of the granite traffic was usually low and slow moving, so passage along

11528-479: The only bridge on the tramway, crossing the Bovey leat , until the opening of the second quarry at Holwell Tor. Ventiford Cottages were built to house employees who worked on the tramway and canal, although some lived in a collection of small houses clustered around the inn which lay below Haytor Rocks. Stables were also maintained here for the horses that worked the canal and the railway. Granite setts can clearly be seen in

11659-441: The overlying crust. Early fractional crystallisation serves to reduce a melt in magnesium and chromium, and enrich the melt in iron, sodium, potassium, aluminum, and silicon. Further fractionation reduces the content of iron, calcium, and titanium. This is reflected in the high content of alkali feldspar and quartz in granite. The presence of granitic rock in island arcs shows that fractional crystallization alone can convert

11790-522: The practice of traffic in Britain driving on the left . A fire in September 1725 destroyed all the houses south of the stone gate; they were rebuilt. The last houses to be built on the bridge were designed by George Dance the Elder in 1745, but these buildings had begun to subside within a decade. The London Bridge Act 1756 ( 29 Geo. 2 . c. 40) gave the City Corporation the power to purchase all

11921-496: The properties on the bridge so that they could be demolished and the bridge improved. While this work was underway, a temporary wooden bridge was constructed to the west of London Bridge. It opened in October 1757 but caught fire and collapsed in the following April. The old bridge was reopened until a new wooden construction could be completed a year later. To help improve navigation under the bridge, its two centre arches were replaced by

12052-431: The quarries employed about 100 men but by 1858 they had closed due to the availability of cheaper Cornish granite. The Haytor rocks and quarries are protected from development and disturbance as a Site of Special Scientific Interest . The granite from the quarries near Haytor Rock was much in demand for construction work in the cities of England, but in an era when railways and reliable roads had not yet been developed,

12183-635: The reason for the quarry and tramway's creation was most likely a contract for George Templer to use the stone for London Bridge . Part of the British Museum , the old General Post Office in London and the Waltham Monument in Ludgate Circus were built of Haytor granite in the 19th century. The last use of Haytor quarried granite was the building of the Exeter War Memorial . The splitting of

12314-702: The reign of Amenemhat III once had a polished granite pyramidion or capstone, which is now on display in the main hall of the Egyptian Museum in Cairo (see Dahshur ). Other uses in Ancient Egypt include columns , door lintels , sills , jambs , and wall and floor veneer. How the Egyptians worked the solid granite is still a matter of debate. Tool marks described by the Egyptologist Anna Serotta indicate

12445-410: The reign of Stephen . Henry II created a monastic guild, the "Brethren of the Bridge", to oversee all work on London Bridge. In 1163, Peter of Colechurch , chaplain and warden of the bridge and its brethren, supervised the bridge's last rebuilding in timber. After the murder of his former friend and later opponent Thomas Becket , Archbishop of Canterbury , the penitent King Henry II commissioned

12576-420: The relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF classification ), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites ) contain almost no dark minerals. Granite is nearly always massive (lacking any internal structures), hard (falling between 6 and 7 on

12707-461: The result that there was a firebreak that prevented the Great Fire of London (1666) spreading to the rest of the bridge and to Southwark. The Great Fire destroyed the bridge's waterwheels, preventing them from pumping water to fight the fire. For nearly 20 years, only sheds replaced the burnt buildings. They were replaced In the 1680s, when almost all the houses on the bridge were rebuilt. The roadway

12838-551: The risk factors in granite country and design rules relating, in particular, to preventing accumulation of radon gas in enclosed basements and dwellings. A study of granite countertops was done (initiated and paid for by the Marble Institute of America) in November 2008 by National Health and Engineering Inc. of USA. In this test, all of the 39 full-size granite slabs that were measured for the study showed radiation levels well below

12969-489: The river upstream was more susceptible to freezing. The number of houses on the bridge reached its maximum in the late fourteenth century, when there were 140. Subsequently, many of the houses, originally only 10 to 11 feet wide, were merged, so that by 1605 there were 91. Originally they are likely to have had only two storeys , but they were gradually enlarged. In the seventeenth century, when there are detailed descriptions of them, almost all had four or five storeys (counting

13100-481: The river's tidal ebb and flow. The difference in water levels on the two sides of the bridge could be as much as 6 feet (1.8 m), producing ferocious rapids between the piers resembling a weir . Only the brave or foolhardy attempted to "shoot the bridge" – steer a boat between the starlings when in flood – and some were drowned in the attempt. The bridge was "for wise men to pass over, and for fools to pass under." The restricted flow also meant that in hard winters

13231-418: The rock's high quartz content and dearth of available bases, with the base-poor status predisposing the soil to acidification and podzolization in cool humid climates as the weather-resistant quartz yields much sand. Feldspars also weather slowly in cool climes, allowing sand to dominate the fine-earth fraction. In warm humid regions, the weathering of feldspar as described above is accelerated so as to allow

13362-451: The rock. A long string of carriages, filled with elegant and beautiful females, multitudes of horsemen, workmen on foot, the wagons covered with laurels and waving streamers, formed in their windings through the valley, an attractive scene to spectators on the adjacent hill. Old Haytor seemed alive: its sides were lined with groups of persons, and on its top a proud flag fluttered in the wind. Previously to returning to dine, Mr Templer addressed

13493-414: The rocks often bear a close resemblance. Under these conditions, granitic melts can be produced in place through the partial melting of metamorphic rocks by extracting melt-mobile elements such as potassium and silicon into the melts but leaving others such as calcium and iron in granulite residues. This may be the origin of migmatites . A migmatite consists of dark, refractory rock (the melanosome ) that

13624-489: The roof of a shallow magma chamber accompanied by a caldera eruption.) There is evidence for cauldron subsidence at the Mt. Ascutney intrusion in eastern Vermont. Evidence for piecemeal stoping is found in intrusions that are rimmed with igneous breccia containing fragments of country rock. Assimilation is another mechanism of ascent, where the granite melts its way up into the crust and removes overlying material in this way. This

13755-524: The route by the public on foot or horseback would not have been particularly hazardous. It may be that pedestrians and riders were asked to pay a toll as on the Kilmarnock and Troon Railway in Ayrshire , Scotland. Milestones were erected, marking distances from Ventiford. Passengers were never carried and the milestones may have been a whim on behalf of George Templer. The four surviving stones, classified by

13886-437: The ship and the bridge. On Remembrance Day 2004, several bridges in London were furnished with red lighting as part of a night-time flight along the river by wartime aircraft. London Bridge was the one bridge not subsequently stripped of the illuminations, which are regularly switched on at night. The current London Bridge is often shown in films, news and documentaries showing the throng of commuters journeying to work into

14017-452: The stone gate, all of which seem to have been present soon after the bridge's construction. The chapel was last rebuilt in 1387–1396, by Henry Yevele , master mason to the king. Following the Reformation , it was converted into a house in 1553. The drawbridge tower was where the severed heads of traitors were exhibited. The drawbridge ceased to be opened in the 1470s and in 1577–1579 the tower

14148-435: The surface than magmas of I-type granites, which are thus more common as volcanic rock (rhyolite). They are also orogenic but range from metaluminous to strongly peraluminous. Although both I- and S-type granites are orogenic, I-type granites are more common close to the convergent boundary than S-type. This is attributed to thicker crust further from the boundary, which results in more crustal melting. A-type granites show

14279-401: The tide was low, or ferry when it was high. Both embankments, particularly the northern, would have offered stable beachheads for boat traffic up and downstream – the Thames and its estuary were a major inland and Continental trade route from at least the 9th century BC. There is archaeological evidence for scattered Neolithic, Bronze Age and Iron Age settlement nearby, but until a bridge

14410-474: The transport of this heavy and bulky commodity was a significant problem. Coastal shipping was a practicable transport medium, and the Stover Canal was available from Ventiford to the Teign Navigation. The Haytor Tramway was constructed to carry the granite the 10 miles (16 km) to the canal, which involved a falling vertical interval of 1,300 feet (400 m) to the basin of the Stover Canal. Its form

14541-469: The upward journey and at the rear for the downward. An old sailor called Thomas Taverner wrote a poem which gives us this information:  Nineteen stout horses it was known,     From Holwell Quarry drew the stone,     And mounted on twelve-wheeled car     'Twas safely brought from Holwell Tor. The vehicles used were probably adapted road waggons and were about 13 feet (3.96 m) long, with

14672-502: The uranium washes into the sediments from the granite uplands and associated, often highly radioactive pegmatites. Cellars and basements built into soils over granite can become a trap for radon gas, which is formed by the decay of uranium. Radon gas poses significant health concerns and is the number two cause of lung cancer in the US behind smoking. Thorium occurs in all granites. Conway granite has been noted for its relatively high thorium concentration of 56±6 ppm. There

14803-599: The use of flint tools on finer work with harder stones, e.g. when producing the hieroglyphic inscriptions. Patrick Hunt has postulated that the Egyptians used emery , which has greater hardness. The Seokguram Grotto in Korea is a Buddhist shrine and part of the Bulguksa temple complex. Completed in 774 AD, it is an artificial grotto constructed entirely of granite. The main Buddha of

14934-473: The walled City of London and Southwark. The earliest contemporary written reference to a Saxon bridge is c.  1016 , when chroniclers mention how Cnut 's ships bypassed the crossing during his war to regain the throne from Edmund Ironside . Following the Norman conquest in 1066, King William I rebuilt the bridge. It was repaired or replaced by King William II , destroyed by fire in 1136, and rebuilt in

15065-403: The wheels of the wagons. The track was laid with the upstand inside the wheels, and the gauge is measured across the two faces of the upstand. The track surface averaged 4 inches (100 mm) in width but could be up to 6 inches (150 mm). As the wagons had plain wheels without flanges, they could be manoeuvred at the terminals without the need for sidings and points. The gauge of the track

15196-446: Was 4 ft ( 1,219 mm ) but varied by up to 3 inches (76 mm), and at junctions the wheels were guided by 'point tongues', pivoted on the granite-block rails. Authorities differ on whether the point tongues were oak or iron. In the upward direction, the empty tram wagons were pulled to the quarries by teams of horses; the loaded trams were run downhill by gravity to the Stover Canal basin at Ventiford, Teigngrace . The route

15327-402: Was "far softer and easier to work than after it has lain exposed" while ancient columns, because of their "hardness and solidity have nothing to fear from fire or sword, and time itself, that drives everything to ruin, not only has not destroyed them but has not even altered their colour." London Bridge The name " London Bridge " refers to several historic crossings that have spanned

15458-399: Was a close relative of a plateway , where longitudinal L-shaped metal plates were used to support and guide the wheels of wagons. In the Haytor case, the "plates" were cut from granite blocks. The blocks were from 4 feet (1.2 m) to 8 feet (2.4 m) long and about 1 foot (0.30 m) square. The outer surface of the blocks was cut away to make the track leaving an upstand which guided

15589-418: Was built out of the granite it would carry and ran from the Haytor quarries to Ventiford Quay on the Stover Canal. At first, it was about 7 miles (11 km) long, but it was later extended to about 9 miles (14 km) or 10 miles (16 km) including the various sidings. The hard granite stone was well-suited to the purpose as it can withstand high pressures and was laid in lieu of iron rails. The tramway had

15720-459: Was built there, London did not exist. A few miles upstream , beyond the river's upper tidal reach, two ancient fords were in use. These were apparently aligned with the course of Watling Street , which led into the heartlands of the Catuvellauni , Britain's most powerful tribe at the time of Caesar's invasion of 54 BC . Some time before Claudius 's conquest of AD 43, power shifted to

15851-465: Was carefully engineered to follow a consistent downward gradient to the canal basin, following the contours of the land (although one of the upper branches had a contrary gradient, requiring horse draught in the loaded direction). A siding at Manaton Road may have been used to allow trains to pass when meeting in opposing directions. The Stover Canal had been built between 1790 and 1792 by James II Templer (1748–1813) of Stover House , Teigngrace , for

15982-475: Was chosen instead. It was built 100 feet (30 m) west (upstream) of the original site by Jolliffe and Banks of Merstham , Surrey , under the supervision of Rennie's son . Work began in 1824 and the foundation stone was laid, in the southern coffer dam , on 15 June 1825. The old bridge continued in use while the new bridge was being built, and was demolished after the latter opened in 1831. New approach roads had to be built, which cost three times as much as

16113-434: Was installed in 1661; subsequently heads were placed on Temple Bar instead, until the practice ceased. There were two multi-seated public latrines , but they seem to have been at the two ends of the bridge, possibly on the riverbank. The one at the north end had two entrances in 1306. In 1481, one of the latrines fell into the Thames and five men were drowned. Neither of the latrines is recorded after 1591. In 1578–1582

16244-573: Was marked for later reassembly. The blocks were taken to Merrivale Quarry at Princetown in Devon , where 15 to 20 cm (6 to 8 in) were sliced off the inner faces of many, to facilitate their fixing. (Stones left behind were sold in an online auction when the quarry was abandoned and flooded in 2003. ) 10,000 tons of granite blocks were shipped via the Panama Canal to California , then trucked from Long Beach to Arizona . They were used to face

16375-603: Was met entirely by the Bridge House Estates charity. The current bridge was built in the same location as Rennie's bridge, with the previous bridge remaining in use while the first two girders were constructed upstream and downstream. Traffic was then transferred onto the two new girders, and the previous bridge demolished to allow the final two central girders to be added. In 1984, the British warship HMS Jupiter collided with London Bridge, causing significant damage to both

16506-408: Was rebuilt and eventually, became the administrative and mercantile capital of Roman Britain. The bridge offered uninterrupted, mass movement of foot, horse, and wheeled traffic across the Thames, linking four major arterial road systems north of the Thames with four to the south. Just downstream of the bridge were substantial quays and depots, convenient to seagoing trade between Britain and the rest of

16637-566: Was replaced by Nonsuch House —a pair of magnificent houses. Its architect was Lewis Stockett, Surveyor of the Queen's Works, who gave it the second classical facade in London (after Somerset House in the Strand). The stone gate was last rebuilt in the 1470s, and later took over the function of displaying the heads of traitors. The heads were dipped in tar and boiled to preserve them against the elements, and were impaled on pikes. The head of William Wallace

16768-405: Was sufficient to produce granite melts by radiogenic heating , but recent work suggests that this is not a viable mechanism. In-situ granitization requires heating by the asthenospheric mantle or by underplating with mantle-derived magmas. Granite magmas have a density of 2.4 Mg/m , much less than the 2.8 Mg/m of high-grade metamorphic rock. This gives them tremendous buoyancy, so that ascent of

16899-564: Was supposed to occur across a migrating front. However, experimental work had established by the 1960s that granites were of igneous origin. The mineralogical and chemical features of granite can be explained only by crystal-liquid phase relations, showing that there must have been at least enough melting to mobilize the magma. However, at sufficiently deep crustal levels, the distinction between metamorphism and crustal melting itself becomes vague. Conditions for crystallization of liquid magma are close enough to those of high-grade metamorphism that

17030-412: Was the first recorded as appearing, in 1305, starting a long tradition. Other famous heads on pikes included those of Jack Cade in 1450, Thomas More in 1535, Bishop John Fisher in the same year, and Thomas Cromwell in 1540. In 1598, a German visitor to London, Paul Hentzner , counted over 30 heads on the bridge: On the south is a bridge of stone eight hundred feet in length, of wonderful work; it

17161-459: Was widened to 20 feet (6.1 metres) by setting the houses further back, and was increased in height from one storey to two. The new houses extended further back over the river, which would cause trouble later. In 1695, the bridge had 551 inhabitants. From 1670, attempts were made to keep traffic in each direction to one side, at first through a keep-right policy and from 1722, through a keep-left policy. This has been suggested as one possible origin for

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