The Chiltern Hills are a chalk escarpment in south east England. They are known locally as "the Chilterns". A large portion of the hills was designated officially as an Area of Outstanding Natural Beauty in 1965.
The boundary of the hills is clearly defined on the north west side by the scarp slope. The dip slope, by its nature, merges with the landscape to the south east. Similarly, the Thames provides a clear terminal whereas, north east of Luton, the hills decline slowly in prominence.
The scarp overlooks the Vale of Aylesbury, and approximately coincides with the southernmost extent of the ice sheet during the last ice age. The Chilterns are part of the Southern England Chalk Formation which also includes Salisbury Plain, Cranborne Chase, the Isle of Wight and the South Downs, in the south. In the north, the chalk formations continue north-eastwards across north Hertfordshire, Norfolk and the Lincolnshire Wolds, finally ending as the Yorkshire Wolds in a prominent escarpment, south of the Vale of Pickering.
Their highest point is 267 m (876 ft) at Haddington Hill in Wendover Woods, Buckinghamshire, near Wendover; a stone marks the summit. A prominent hill is the nearby Ivinghoe Beacon, standing 249m (817ft) above sea level, the starting point of the Icknield Way 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 that is the site of the famous London Gliding Club and Whipsnade Zoo. Near Wendover is Coombe Hill which is 260 m (853 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 The Chilterns, containing much beech woodland and many pretty villages.
Rivers that drain from the Chiltern Hills include the River Mimram, River Lee, River Ver, River Bulbourne, River Misbourne, River Chess, River Wye and River Gade and are classified as chalk streams.
The opening credits of the BBC comedy The Vicar of Dibley feature an aerial shot of the Stokenchurch Gap. This is a major excavation which eases the M40 motorway from the Chilterns into the Vale of Oxford. It is between junctions 5 and 6. The chalk that forms the hills can clearly be seen on both sides of the cutting when driving on the motorway.
In pre-Roman times, the Chiltern ridge provided a relatively safe and easily negotiable route, thus the Icknield Way (one of England's ancient trackways) follows the line of the hills.
One of the principal Roman settlements in Britannia was sited at Verulamium (now St Albans) and there are significant Roman and Romano-British remains in the area.
The Tudors had a hunting lodge in the Hemel Hempstead area.
Until the coming of the railways and, later, the motor-car, the Chilterns were largely rural with country towns situated on the main routes through the hills. The position of the hills, north-west of London, has affected the routing of major road, rail and canal routes. These were funnelled through convenient valleys (eg, High Wycombe, Hemel Hempstead) and encouraged settlement and, later, commuter housing.
The hills have been exploited for their natural resources for thousands of years. The chalk has been quarried for the manufacture of cement. Beechwoods supplied furniture makers with quality hardwood. The area 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).