Chiltern Hills


The Chiltern Hills or the Chilterns are a chalk escarpment in southern England to the northwest of London, covering 660 square miles across Oxfordshire, Buckinghamshire, Hertfordshire and Bedfordshire and stretching from Goring-on-Thames in the southwest to Hitchin in the northeast. The hills are at their widest.
In 1964, 833 square kilometres - almost half of the Chiltern Hills - were designated by the Countryside Commission
as an Area of Outstanding Natural Beauty under the powers established by the National Parks and Access to the Countryside Act 1949.
The northwest 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 southeast. The southwest endpoint is the River Thames. The hills decline slowly in prominence in northeast Bedfordshire.

Geology

The chalk escarpment of the Chiltern Hills overlooks 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, consisting of rocks of the Chalk Group, formed between 95 and 65 million years ago; it also includes Salisbury Plain, Cranborne Chase, the Isle of Wight and the South Downs in 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 owing to 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 base of 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 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 the Chiltern Hills. 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 m 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 m. It is the starting point of the Icknield Way Path and the Ridgeway long-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 is Dunstable Downs, a steep section of the Chiltern scarp. Near Wendover is Coombe Hill, 260 m 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 and contains much beech woodland and many villages.

Landscape and land use

fields account for almost 66% of the Area of Outstanding Natural Beauty. 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 make up more than 5% of the land area; parks and gardens nearly 4%, open land is 2%, and the remaining 2% includes a variety of uses, including communications, military, open land, recreation, utilities and water.

Rivers

The Chilterns are almost entirely within 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 the Lea is degraded by water from road drains and sewage 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.

Transport

Several transport routes pass through the Chilterns in natural or human-made corridors. There are also over of public footpaths in 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, the London to Aylesbury Line via, 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 will pass underneath the Chilterns in the Chiltern tunnel. This tunnel, the longest under construction on the HS2 route, will be 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 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.

History

During the Iron Age, the Chiltern ridge provided a relatively safe and easily navigable route across southern Britain.
The toponym, Chiltern, is believed to be Brittonic in origin. According to Eilert Ekwall, Chiltern is possibly related to the broader ethnic name Celt ; the root celto- "high" 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 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 was designated as an Area of Outstanding Natural Beauty.

List of towns and villages in the Chilterns

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 was once renowned for its chair-making industry, centred on the towns of Chesham and High Wycombe.
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.
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 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 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.