46-469: The Chiltern Hills or the Chilterns are a chalk escarpment in southern England, northwest of London, covering 660 square miles (1,700 km) across Oxfordshire , Buckinghamshire , Hertfordshire , and Bedfordshire , stretching 45 miles (72 km) from Goring-on-Thames in the southwest to Hitchin in the northeast. The hills are 12 miles (19 km) at their widest. In 1965, almost half of
92-474: Is Coombe Hill , 260 m (852 ft.) above sea level. The more gently sloping country – the dip slope – to the southeast of the Chiltern scarp is also generally referred to as part of the Chilterns; it contains much beech woodland and many villages. Enclosed fields account for almost 66% of the " Area of Outstanding Natural Beauty " (AONB) area. The next most important, and archetypal, landscape form
138-642: Is mined from chalk deposits both above ground and underground . Chalk mining boomed during the Industrial Revolution , due to the need for chalk products such as quicklime and bricks . Most people first encounter chalk in school where it refers to blackboard chalk , which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacturers now may use mineral chalk, other mineral sources of calcium carbonate, or
184-496: Is woodland , covering 21% of the Chilterns, which is thus one of the most heavily wooded areas in England. Built-up areas (settlements and industry) make up over 5% of the land area; parks and gardens nearly 4%, open land (commons, heaths and downland) is 2%, and the remaining 2% includes a variety of uses, including communications, military, open land, recreation, utilities and water. The Chilterns are almost entirely located within
230-579: Is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor . Chalk is common throughout Western Europe , where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel . Chalk
276-596: Is a more prominent hill, although its altitude is only 249 m (817 ft.). It is the starting point of the Icknield Way Path and the Ridgeway long-distance path , which follows the line of the Chilterns for many miles to the west, where they merge with the Wiltshire downs and southern Cotswolds . To the east of Ivinghoe Beacon is Dunstable Downs, a steep section of the Chiltern scarp. Near Wendover
322-508: Is also the only form of limestone that commonly shows signs of compaction. Flint (a type of chert ) is very common as bands parallel to the bedding or as nodules in seams , or linings to fractures , embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i.e. replaced molecule by molecule by flint). Chalk
368-428: Is applied to the hands and feet to remove perspiration and reduce slipping. Chalk may also be used as a house construction material instead of brick or wattle and daub : quarried chalk was cut into blocks and used as ashlar , or loose chalk was rammed into blocks and laid in mortar. There are still houses standing which have been constructed using chalk as the main building material. Most are pre- Victorian though
414-439: Is believed to be Brittonic in origin. According to Eilert Ekwall , Chiltern is possibly related to the broader ethnic name Celt ( Celtæ in early Celtic languages ); the root celto- "high" (and suffix -erno- ) could provide the origin of Chiltern . Before the 18th century, the population lived dispersed across the largely rural landscape of the Chilterns in remote villages, hamlets, farmsteads, and market towns along
460-518: Is commonly used as a drying agent to obtain better grip by gymnasts and rock climbers. Glazing putty mainly contains chalk as a filler in linseed oil . Chalk and other forms of limestone may be used for their properties as a base . Chalk is a source of quicklime by thermal decomposition , or slaked lime following quenching of quicklime with water. In agriculture , chalk is used for raising pH in soils with high acidity . Small doses of chalk can also be used as an antacid . Additionally,
506-494: Is composed mostly of tiny fragments of the calcite shells or skeletons of plankton , such as foraminifera or coccolithophores . These fragments mostly take the form of calcite plates ranging from 0.5 to 4 microns in size, though about 10% to 25% of a typical chalk is composed of fragments that are 10 to 100 microns in size. The larger fragments include intact plankton skeletons and skeletal fragments of larger organisms, such as molluscs , echinoderms , or bryozoans . Chalk
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#1732772007790552-464: Is mined for use in industry, such as for quicklime , bricks and builder's putty , and in agriculture , for raising pH in soils with high acidity . It is also used for " blackboard chalk " for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals, or gypsum . Chalk is a fine-textured, earthy type of limestone distinguished by its light colour, softness, and high porosity. It
598-582: Is now usually made of talc (magnesium silicate). Chalk beds form important petroleum reservoirs in the North Sea and along the Gulf Coast of North America. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines, where the prime object was to remove flint nodules for stone tool manufacture. The surface remains at Cissbury are one such example, but perhaps
644-554: Is so common in Cretaceous marine beds that the Cretaceous Period was named for these deposits. The name Cretaceous was derived from Latin creta , meaning chalk . Some deposits of chalk were formed after the Cretaceous. The Chalk Group is a European stratigraphic unit deposited during the late Cretaceous Period. It forms the famous White Cliffs of Dover in Kent , England, as well as their counterparts of
690-401: Is typically almost pure calcite, CaCO 3 , with just 2% to 4% of other minerals. These are usually quartz and clay minerals , though collophane (cryptocrystalline apatite , a phosphate mineral) is also sometimes present, as nodules or as small pellets interpreted as fecal pellets. In some chalk beds, the calcite has been converted to dolomite , CaMg(CO 3 ) 2 , and in a few cases
736-752: The Cap Blanc Nez on the other side of the Dover Strait . The Champagne region of France is mostly underlain by chalk deposits, which contain artificial caves used for wine storage . Some of the highest chalk cliffs in the world occur at Jasmund National Park in Germany and at Møns Klint in Denmark . Chalk deposits are also found in Cretaceous beds on other continents, such as the Austin Chalk , Selma Group , and Niobrara Formations of
782-814: The House of Commons of the United Kingdom , who are prohibited from resigning their seats directly, may apply for the Stewardship of the Chiltern Hundreds as a device to enable their departure from the House. Hills in The Chilterns more than 200 metres in elevation and with more than 30 metres of topographic prominence are listed from southwest to northeast. Chalk Chalk is a soft, white, porous , sedimentary carbonate rock . It
828-783: The London to Aylesbury Line via Amersham , the West Coast Main Line via Berkhamsted , and the Midland Main Line all run through the Chiltern Hills. The Great Western Main Line and its branches such as the Henley and Marlow branch lines link the southern side of the Chilterns with London Paddington . The Chinnor and Princes Risborough Railway is a preserved line. High Speed 2 (HS2) will pass underneath
874-987: The River Thames drainage basin , and also drain towards several major Thames tributaries, most notably the Lea , which rises in the eastern Chilterns, the Colne to the south, and the Thame to the north and west. Other rivers arising near the Chilterns include the Mimram , the Ver , the Gade , the Bulbourne , the Chess , the Misbourne and the Wye . These are classified as chalk streams , although
920-523: The River Thames , there are no navigable rivers. The Grand Union Canal passes through the Chilterns between Berkhamsted and Marsworth following the course of the Gade and Bulbourne . Also, after crossing a watershed, the Ouzel is partly in the Chilterns. During the Iron Age , the Chiltern ridge provided a relatively safe and easily navigable route across southern Britain. The toponym , Chiltern ,
966-686: The Vale of Aylesbury and roughly coincides with the southernmost extent of the ice sheet during the Anglian glacial maximum . The Chilterns are part of a system of chalk downlands throughout eastern and southern England, formed between 65 and 95 million years ago, comprising rocks of the Chalk Group ; this also includes Salisbury Plain , Cranborne Chase , the Isle of Wight and the South Downs in
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#17327720077901012-517: The Weald Basin of southern England, underwent structural inversion . This phase of deformation tilted the chalk strata to the southeast in the area of the Chiltern Hills. The gently dipping beds of rock were eroded , forming an escarpment. The chalk strata are frequently interspersed with layers of flint nodules which apparently replaced chalk and infilled pore spaces early in the diagenetic history. Flint has been mined for millennia from
1058-561: The AONB. Third, to publish and promote the implementation of a management plan for the AONB. In contrast to National Parks , The Chilterns – as other AONBs – do not possess their own planning authority . The Board has an advisory role on planning and development matters and seeks to influence the actions of local government by commenting upon planning applications . The local authorities (two County Councils, three Unitary Authorities and four District and Borough Councils) are expected to respect
1104-531: The Chiltern AONB area. The Board's purposes are set out in Countryside and Rights of Way Act 2000 : In summary these are:- First, to conserve and enhance the natural beauty of the AONB, and increase the understanding and enjoyment by the public of the special qualities of the AONB. Second, while taking account of the first purpose, to foster the economic and social wellbeing of local communities within
1150-548: The Chiltern Hills. They were first extracted for fabrication into flint axes in the Neolithic period, then for knapping into flintlocks . Nodules are to be seen everywhere in the older houses as a construction material for walls. The highest point is at 267 m (876 ft.) above sea level at Haddington Hill near Wendover in Buckinghamshire; a stone monument marks the summit . The nearby Ivinghoe Beacon
1196-568: The Chilterns in the Chiltern tunnel . This tunnel, the longest under construction on the HS2 route, will be 16 km (9.9 miles) in length. The Conservation Board has made clear it was opposed to the routing of HS2 through the Chilterns AONB. Bus services are provided by Arriva Shires & Essex and Carousel Buses . Air corridors from Luton Airport pass over the Chilterns. Apart from
1242-406: The Chilterns was designated as an Area of Outstanding Natural Beauty (AONB). The northwest boundary is clearly defined by the escarpment . The dip slope is by definition more gradual, and merges with the landscape to the southeast. The southwest endpoint is the River Thames . The hills decline slowly in prominence in northeast Bedfordshire. The chalk escarpment of the Chiltern Hills overlooks
1288-782: The Chilterns, including long-distance trackways such as the Icknield Way and The Ridgeway . The M40 motorway passes through the Chilterns in Buckinghamshire and Oxfordshire sections with a deep cutting through the Stokenchurch Gap . The M1 motorway crosses the Bedfordshire section near Luton . Other major roads include the A41 and the A413 . The Chiltern Main Line Railway via High Wycombe and Princes Risborough ,
1334-834: The Lea is degraded by water from road drains and sewage treatment works. The Thames flows through a gap between the Berkshire Downs and the Chilterns. Portions around Leighton Buzzard and Hitchin are drained by the Ouzel , the Flit and the Hiz , all of which ultimately flow into the River Great Ouse (the last two via the Ivel ). Several transport routes pass through the Chilterns in natural or human-made corridors. There are also over 2,000 km (1,200 mi) of public footpaths in
1380-732: The North American interior. Chalk is also found in western Egypt (Khoman Formation) and western Australia ( Miria Formation ). Chalk of Oligocene to Neogene age has been found in drill cores of rock under the Pacific Ocean at Stewart Arch in the Solomon Islands . There are layers of chalk, containing Globorotalia , in the Nicosia Formation of Cyprus , which formed during the Pliocene . Chalk
1426-622: The area's status as a designated Area of Outstanding Natural Beauty. Examples of historical architecture in the Chiltern region are preserved at the Chiltern Open Air Museum near Chalfont St Giles . This open-air folk museum contains reconstructed buildings which might otherwise have been destroyed or demolished as a result of redevelopment or road construction. The Chilterns include the Chiltern Hundreds . By established custom, Members of Parliament (MPs) in
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1472-485: The chalk aquifer is exploited via a network of pumping stations to provide a public supply for domestic consumption, agriculture and business uses, both within and well-beyond the Chilterns area. Over-exploitation has possibly led to the disappearance of some streams over long periods. In a region without building stone, local clay provided the raw materials for brick manufacture. Timber and flint were also used for construction. Mediaeval strip parishes reflected
1518-548: The chalk came mostly form low-magnesium calcite skeletons, so the sediments were already in the form of highly stable low-magnesium calcite when deposited. This is in contrast with most other limestones, which formed from high-magnesium calcite or aragonite that rapidly converted to the more stable low-magnesium calcite after deposition, resulting in the early cementation of such limestones. In chalk, absence of this calcium carbonate conversion process prevented early cementation, which partially accounts for chalk's high porosity. Chalk
1564-552: The diversity of land from clay farmland , through wooded slopes to downland. Their boundaries were often drawn to include a section of each type of land, resulting in an irregular county boundary. These have tended to be smoothed out by successive reorganisations. As people have come to appreciate the open country, the area has become a visitor destination and the National Trust has acquired land to preserve its character, for example at Ashridge , near Tring . In places, with
1610-494: The dolomitized chalk has been dedolomitized back to calcite. Chalk is highly porous, with typical values of porosity ranging from 35 to 47 per cent. While it is similar in appearance to both gypsum and diatomite , chalk is identifiable by its hardness, fossil content, and its reaction to acid (it produces effervescence on contact). In Western Europe, chalk was formed in the Late Cretaceous Epoch and
1656-437: The early Palaeocene Epoch (between 100 and 61 million years ago). It was deposited on extensive continental shelves at depths between 100 and 600 metres (330 and 1,970 ft), during a time of nonseasonal (likely arid) climate that reduced the amount of erosion from nearby exposed rock. The lack of nearby erosion explains the high purity of chalk. The coccolithophores, foraminifera, and other microscopic organisms from which
1702-674: The exceptionally high sea level. The formation is thinner through the Chiltern Hills than the chalk strata to the north and south and deposition was tectonically controlled, with the Lilley Bottom structure playing a significant role at times. The Chalk Group, like the underlying Gault Clay and Upper Greensand , is diachronous . During the late stages of the Alpine Orogeny , as the African Plate collided with Eurasian Plate , Mesozoic extensional structures, such as
1748-495: The government confirmed that the landscape qualities of AONBs are equivalent to those of National Parks, and that the protection given to both types of area by the land use planning system should also be equivalent. The Chilterns Conservation Board was established by Parliamentary Order in July 2004. It is an independent body comprising 27 members drawn from the relevant local authorities and from those living in local communities within
1794-409: The main turnpike routes which coursed through the navigable valleys. The development of canals in the 18th century and railways in the 19th century encouraged settlement and the growth of High Wycombe , Tring , and Luton . Significant housing and industrial development took place in the first half of the 20th century and continued throughout the 20th century. In 1965 almost half of the Chiltern Hills
1840-528: The mineral gypsum ( calcium sulfate ). While gypsum-based blackboard chalk is the lowest cost to produce, and thus widely used in the developing world , use of carbonate-based chalk produces larger particles and thus less dust, and it is marketed as "dustless chalk". Coloured chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often coloured), used to draw on sidewalks , streets, and driveways , are primarily made of gypsum rather than calcium carbonate chalk. Magnesium carbonate chalk
1886-562: The most famous is the extensive complex at Grimes Graves in Norfolk . Chalk was traditionally used in recreation. In field sports, such as tennis played on grass, powdered chalk was used to mark the boundary lines of the playing field or court. If a ball hits the line, a cloud of chalk or pigment dust will be visible. In recent years, powdered chalk has been replaced with titanium dioxide . In gymnastics, rock-climbing, weightlifting and tug of war , chalk — now usually magnesium carbonate —
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1932-798: The reduction of sheep grazing , action has been taken to maintain open downland by suppressing the natural growth of scrub and birch woodland. In the 1920s and 1930s, the Youth Hostels Association established several youth hostels for people visiting the hills. The hills have been used as a location for telecommunication relay stations such as Stokenchurch BT Tower and that at Zouches Farm . The Chilterns are an Area of Outstanding Natural Beauty (AONB) and so enjoys special protection from major developments, which should not take place in such areas except in exceptional circumstances. This protection applies to major development proposals that raise issues of national significance. In 2000
1978-436: The small particles of chalk make it a substance ideal for cleaning and polishing. For example, toothpaste commonly contains small amounts of chalk, which serves as a mild abrasive . Polishing chalk is chalk prepared with a carefully controlled grain size, for very fine polishing of metals. French chalk (also known as tailor's chalk) is traditionally a hard chalk used to make temporary markings on cloth, mainly by tailors . It
2024-779: The south. In the north, the chalk formations continue northeastwards across Hertfordshire , Norfolk and the Lincolnshire Wolds , finally ending as the Yorkshire Wolds in a prominent escarpment, south of the Vale of Pickering . The beds of the Chalk Group were deposited over the buried northwestern margin of the Anglo-Brabant Massif during the Late Cretaceous . During this time, sources for siliciclastic sediment had been eliminated due to
2070-519: Was designated as an Area of Outstanding Natural Beauty (AONB). The western edge of the Chilterns is notable for ancient strip parishes , elongated parishes with villages in the flatter land below the escarpment, and woodland and summer pastures in the higher land. The hills have been used for their natural resources for millennia . The chalk has been quarried for the manufacture of cement, and flint for local building material. Beechwoods supplied furniture makers with quality hardwood . The area
2116-511: Was once (and still is to a lesser degree) renowned for its chair-making industry, centred on the towns of Chesham and High Wycombe (the nickname of Wycombe Wanderers Football Club is the Chairboys). Water was and remains a scarce resource in the Chilterns. Historically it was drawn from the aquifer via ponds , deep wells , occasional springs or bournes and chalk streams and rivers. The River Chess directly supplies watercress beds. Today
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