The Chiltern Hills or the Chilterns (/ˈtʃɪltən/ ⓘ) are a chalk escarpment in southern England to the north-west of London, covering 660 mi2 (1,700 km2) across Oxfordshire, Buckinghamshire, Hertfordshire and Bedfordshire.
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The north-west boundary of the Chilterns is clearly defined by the escarpment. The dip slope is by definition more gradual and merges with the landscape to the south-east.4 The south-west endpoint is the River Thames. The hills decline slowly in prominence in north-east Bedfordshire.56
Toponymy
The toponym, Chiltern, is believed to be Brittonic in origin. According to , is possibly related to the broader ethnic name ( in early ); the root "high" (and suffix ) could provide the origin of .
This page is based on “Chiltern Hills” from English Wikipedia, (r1370325472) CC BY-SA 4.0 used under the license. The original authors are listed in its page history.
During the Iron Age, the Chiltern ridge provided a relatively safe and easily navigable route across southern Britain.
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 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 throughout the 20th century.
In 1965, almost half of the Chiltern Hills was designated as an AONB.8
The beds of the Chalk Group were deposited over the buried north-western margin of the Anglo-Brabant Massif during the Late Cretaceous.9 During this time sources for siliciclastic sediment had been eliminated owing to the exceptionally high sea level.10 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.9 The base of the Chalk Group, like the underlying Gault Clay and Upper Greensand, is diachronous.10
During the late stages of the Alpine Orogeny, as the African Plate collided with Eurasian Plate, Mesozoic extensional structures, such as the Weald Basin of southern England, underwent structural inversion.9 This phase of deformation tilted the chalk strata to the south-east 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 flintnodules, which apparently replaced chalk and infilled pore spaces early in the diagenetic history. Flint has been mined for millennia from the Chiltern Hills.11 It was 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.
Physical characteristics
Topography
The highest point is 267 metres (876 ft) above sea level at Haddington Hill, near Wendover in Buckinghamshire; a stone monument marks the summit. The nearby Ivinghoe Beacon is a more prominent hill, although its altitude is only 249 metres (817 ft).12 It is the starting point of the Icknield Way Path and the Ridgewaylong-distance path, which follow 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 are the Dunstable Downs, a steep section of the Chiltern scarp. Near Wendover is Coombe Hill, 260 metres (850 ft) above sea level. The more gently sloping country – the dip slope – to the south-east of the Chiltern scarp is also generally referred to as part of the Chilterns and contains much beechwoodland1 and many villages.
Landscape and land use
Enclosed fields account for almost 66% of the AONB. The next most important, and archetypal, landscape form 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 more than 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.5
Rivers
The Chiltern Hills are almost entirely within the River Thamesdrainage 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 the Lea is degraded by water from road drains and sewage works.13 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.
Transport
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, including long-distance trackways such as the Icknield Way and The Ridgeway.14
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.
High Speed 2 (HS2) will pass underneath the Chilterns in the Chiltern Tunnel; the longest under construction on the route will be 16 km (9.9 miles) in length.15 The Conservation Board was opposed to the routing of HS2 through the Chilterns AONB.1617
Air corridors from Luton Airport pass over the Chilterns.
Apart from the 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.
The western edge of the Chilterns is notable for ancient strip parishes; these are elongated parishes with villages in the flatter land below the escarpment, with woodland and summer pastures in the higher land:4
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 was once (and still is to a lesser degree) renowned for its chair-making industry,1 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 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.18
In a region without building stone, local clay provided the raw materials for brick manufacture; timber and flint were also used for construction.
Mediaevalstrip parishes reflected 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. The National Trust has acquired land to preserve its character, for example at Ashridge, near Tring. In places, with 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 Chilterns is an 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.19 In 2000, 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.
Chilterns Conservation Board
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 the AONB.
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 the AONB.
Third, to publish and promote the implementation of a management plan for the AONB.
In contrast to National Parks, the Chilterns – as with 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.21
The local authorities (two County Councils, three Unitary Authorities and four District and Borough Councils) are expected to respect the area's status as a designated AONB.
Heritage
Examples of historical architecture in the Chiltern region are preserved at the Chiltern Open Air Museum, near Chalfont St Giles. This open-airfolk museum contains reconstructed buildings which might otherwise have been destroyed or demolished as a result of redevelopment or road construction.2223
Poore, Duncan; Poore, Judy (1992) [1987]. Protected Landscapes in the United Kingdom. Countryside Commission Publication, volume 362. Cheltenham: Countryside Commission. p. 39. ISBN 9780861703241. Retrieved 10 April 2025. Chilterns: Designated 1964 833sq km: Confirmed 1965: Variation confirmed 1990 ↩
Ratcliffe, John; Stubbs, Michael (1996). "Specialist town planning controls". Urban Planning And Real Estate Development. London: The UCL Press. pp. 144, 146. ISBN 9781135363185. Retrieved 10 April 2025. National Parks are designated by the Countryside Commission in England [...] under powers contained in the National Parks and Access to the Countryside Act 1949. [...] AONBS are also designated by the Countryside Commission [...]. Thirty-nine such AONBS have been designated in England and Wales [...] Examples include the Chiltern Hills in Buckinghamshire and Bodmin Moor in Devon. ↩
Hepple, Leslie; Doggett, Alison (1971). The Chilterns. England: Phillimore & Co Ltd. ISBN 0-85033-833-6. ↩↩2
Ekwall (1940). The Concise Oxford Dictionary of English Place-names (second ed.). Oxford: Clarendon Press. p. 99. Ekwall cites the forms Cilternsætna (Birch's Cartularium Saxonicum; 297); Cilternes efes (Kemble's Codex diplomaticus aevi Saxonici; 715) and Ciltern (Anglo-Saxon Chronicle; text E) ↩
Rawson, P.F. 2006. Cretaceous: sea levels peak as the North Atlantic opens. In: P.J. Brenchley and P.F. Rawson (Eds) The Geology of England and Wales, p.365-393. The Geological Society ISBN 978-1-86239-200-7 ↩↩2↩3
Anderson, R., P.H. Bridges, M.R. Leeder and B.W. Sellwood (Eds) 1979. A Dynamic Stratigraphy of the British Isles: A Study in Crustal Evolution. p. 241. George Allen and Unwin, London. ISBN 0-412-44510-7 ↩↩2
Hepple, Leslie (1992). The Chilterns. Chichester, Sussex: Phillimore & Co. Ltd. p. 16. ISBN 085033-833-6. ↩
The north-west boundary of the Chilterns is clearly defined by the escarpment. The dip slope is by definition more gradual and merges with the landscape to the south-east.4 The south-west endpoint is the River Thames. The hills decline slowly in prominence in north-east Bedfordshire.56
Toponymy
The toponym, Chiltern, 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.7
History
During the Iron Age, the Chiltern ridge provided a relatively safe and easily navigable route across southern Britain.
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 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 throughout the 20th century.
In 1965, almost half of the Chiltern Hills was designated as an AONB.8
The beds of the Chalk Group were deposited over the buried north-western margin of the Anglo-Brabant Massif during the Late Cretaceous.9 During this time sources for siliciclastic sediment had been eliminated owing to the exceptionally high sea level.10 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.9 The base of the Chalk Group, like the underlying Gault Clay and Upper Greensand, is diachronous.10
During the late stages of the Alpine Orogeny, as the African Plate collided with Eurasian Plate, Mesozoic extensional structures, such as the Weald Basin of southern England, underwent structural inversion.9 This phase of deformation tilted the chalk strata to the south-east 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 flintnodules, which apparently replaced chalk and infilled pore spaces early in the diagenetic history. Flint has been mined for millennia from the Chiltern Hills.11 It was 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.
Physical characteristics
Topography
The highest point is 267 metres (876 ft) above sea level at Haddington Hill, near Wendover in Buckinghamshire; a stone monument marks the summit. The nearby Ivinghoe Beacon is a more prominent hill, although its altitude is only 249 metres (817 ft).12 It is the starting point of the Icknield Way Path and the Ridgewaylong-distance path, which follow 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 are the Dunstable Downs, a steep section of the Chiltern scarp. Near Wendover is Coombe Hill, 260 metres (850 ft) above sea level. The more gently sloping country – the dip slope – to the south-east of the Chiltern scarp is also generally referred to as part of the Chilterns and contains much beechwoodland1 and many villages.
Landscape and land use
Enclosed fields account for almost 66% of the AONB. The next most important, and archetypal, landscape form 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 more than 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.5
Rivers
The Chiltern Hills are almost entirely within the River Thamesdrainage 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 the Lea is degraded by water from road drains and sewage works.13 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.
Transport
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, including long-distance trackways such as the Icknield Way and The Ridgeway.14
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.
High Speed 2 (HS2) will pass underneath the Chilterns in the Chiltern Tunnel; the longest under construction on the route will be 16 km (9.9 miles) in length.15 The Conservation Board was opposed to the routing of HS2 through the Chilterns AONB.1617
Air corridors from Luton Airport pass over the Chilterns.
Apart from the 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.
The western edge of the Chilterns is notable for ancient strip parishes; these are elongated parishes with villages in the flatter land below the escarpment, with woodland and summer pastures in the higher land:4
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 was once (and still is to a lesser degree) renowned for its chair-making industry,1 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 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.18
In a region without building stone, local clay provided the raw materials for brick manufacture; timber and flint were also used for construction.
Mediaevalstrip parishes reflected 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. The National Trust has acquired land to preserve its character, for example at Ashridge, near Tring. In places, with 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 Chilterns is an 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.19 In 2000, 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.
Chilterns Conservation Board
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 the AONB.
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 the AONB.
Third, to publish and promote the implementation of a management plan for the AONB.
In contrast to National Parks, the Chilterns – as with 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.21
The local authorities (two County Councils, three Unitary Authorities and four District and Borough Councils) are expected to respect the area's status as a designated AONB.
Heritage
Examples of historical architecture in the Chiltern region are preserved at the Chiltern Open Air Museum, near Chalfont St Giles. This open-airfolk museum contains reconstructed buildings which might otherwise have been destroyed or demolished as a result of redevelopment or road construction.2223
Poore, Duncan; Poore, Judy (1992) [1987]. Protected Landscapes in the United Kingdom. Countryside Commission Publication, volume 362. Cheltenham: Countryside Commission. p. 39. ISBN 9780861703241. Retrieved 10 April 2025. Chilterns: Designated 1964 833sq km: Confirmed 1965: Variation confirmed 1990 ↩
Ratcliffe, John; Stubbs, Michael (1996). "Specialist town planning controls". Urban Planning And Real Estate Development. London: The UCL Press. pp. 144, 146. ISBN 9781135363185. Retrieved 10 April 2025. National Parks are designated by the Countryside Commission in England [...] under powers contained in the National Parks and Access to the Countryside Act 1949. [...] AONBS are also designated by the Countryside Commission [...]. Thirty-nine such AONBS have been designated in England and Wales [...] Examples include the Chiltern Hills in Buckinghamshire and Bodmin Moor in Devon. ↩
Hepple, Leslie; Doggett, Alison (1971). The Chilterns. England: Phillimore & Co Ltd. ISBN 0-85033-833-6. ↩↩2
Ekwall (1940). The Concise Oxford Dictionary of English Place-names (second ed.). Oxford: Clarendon Press. p. 99. Ekwall cites the forms Cilternsætna (Birch's Cartularium Saxonicum; 297); Cilternes efes (Kemble's Codex diplomaticus aevi Saxonici; 715) and Ciltern (Anglo-Saxon Chronicle; text E) ↩
Rawson, P.F. 2006. Cretaceous: sea levels peak as the North Atlantic opens. In: P.J. Brenchley and P.F. Rawson (Eds) The Geology of England and Wales, p.365-393. The Geological Society ISBN 978-1-86239-200-7 ↩↩2↩3
Anderson, R., P.H. Bridges, M.R. Leeder and B.W. Sellwood (Eds) 1979. A Dynamic Stratigraphy of the British Isles: A Study in Crustal Evolution. p. 241. George Allen and Unwin, London. ISBN 0-412-44510-7 ↩↩2
Hepple, Leslie (1992). The Chilterns. Chichester, Sussex: Phillimore & Co. Ltd. p. 16. ISBN 085033-833-6. ↩