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The North Downs are a ridge of chalk hills located in south east England that stretch for 120 miles (190 km) from Hampshire through Surrey to Kent. They form the northern part of the Wealden dome, of which the South Downs are their mirror image and often reach in excess of 200 metres (660 ft). Often refered to as part of the North Downs is a sandstone ridge just south of the downs known as the Greensand Ridge. The North Downs have been designated as two Areas of Outstanding Natural Beauty (AONBs) - The Surrey Hills and Kent Downs. The North Downs Way National Trail passes through the North Downs from Farnham to Dover.

Contents 1 Geography 1.1 Rivers 2 Geology 3 Ecology 3.1 Chalk grassland 4 Agriculture and industry 5 Places of interest 6 Photo Gallery 7 See also 8 References 9 External links

The North Downs consist of two aspects - the scarp face on its southern side and the dip slope on its northern side. The scarp slope is often steep and cut by coombs whilst the dip slope is gentle with flat plateaus and dry valleys. Where the North Downs meet the sea between Folkestone and Deal they form the famous White cliffs of Dover which reach up to 120 metres high (400 feet). The highest point on the chalk ridge is Botley Hill near Oxted at 267 m in Surrey whilst the highest point on the Greensand Ridge is Leith Hill at 294 m (965 ft) also in Surrey.

The North Downs are divided by five principle rivers:

• Wey
• Mole
• Darent
• Medway
• Stour

The River Dour flows from Kearsney to the sea at Dover. Another characteristic of the downs are winterbournes such as the Nailbourne.

The North Downs are formed by a layer of chalk that rises over the anticline of the Wealden Dome. The chalk consists of three layers: upper, middle and lower. Occuring on the higher slopes of the downs, above the chalk are deposits of clay with flints. At the foot of the scarp slope beneath the chalk is a layer of gault clay. This layer is clearly seen at Fokestone Warren where rotational slipping of the chalk has occurred over the gault clay forming an undercliff.

Beneath the surface of the chalk and other mesozoic formations in East Kent are coal measures with a depth of over 800 metres.

Originally the North Downs was covered by deciduous woodland such as oak and ash (the climax community).

One important ecosystem that occurs on the North Downs is chalk grassland which occurs on steep slopes where the soil is poor and woodland has not encroached due to grazing. This results in wild flower rich grassland which also provides a habitat for many animals particuarly insects. Unlike the South Downs the scarp slope of the North Downs faces south into the sun and thus many continental species of plant thrive on the North Downs whereas they are scarce on the South Downs.

During the twentieth century much chalk downland was lost due to changes in farming methods after World War 2 and the increased use of fertilisers on grassland. The myxomatosis outbreak in 1953 that wiped out 95% of the rabbit population in the UK also led to much chalk grassland reverting to scrubland and woodland. In recent years there have been attempts to revert areas of arable farmland back to chalk grassland such as at the Hucking Estate owned by the Woodland Trust. The Countryside Stewardship Scheme has also attempted to re-establish areas of chalk grassland. Today, nearly 90% of the chalk grassland on the North Downs is protected.

The landscape of the North Downs has been greatly shaped by man. Deforestation has been an important activity that has taken place on the downs for centuries. Today, the woodland that remains largely exists where deforestation has been inhibited by steep slopes or the layer of clay with flints which is difficult to plough. Due to the many small farms that have survived on the downs, a network of narrow lanes and minor roads has developed. This has resulted in a landscape similar to that found in Normandy known as bocage. The predominant type of farming on the downs is arable farming and this increased greatly during the twentieth century. Pastoral farming also occurs but to a lesser extent. Human settlements within the downs have generally formed in sheltered valleys and at the foot of scarp slope (known as spring line settlements).

There is plenty of evidence of chalk extraction on the North Downs particuarly along the scarp slope. Oil drilling at the foot of the downs occurs in several locations in Surrey. The Kent Coalfield was established in the late 19th century after coal was found in 1890. Four collieries produced a succesful output and lasted throughout the 20th century - Betteshanger, Snowdon, Tilmanstone and Chislet. The east to west ridge of the downs has provided a natural transport route for centuries. Much of the historic Pilgrims' Way still survives at the foot of the scarp slope and this has been joined much more recently by the M20 motorway.

There are a number of historic sites within the North Downs. The Medway megaliths are concentrated at the foot of the scarp slope in the Medway valley. The scarp slope has also been used for fortification and many examples of this still exist such as Thurnham Castle and on Castle Hill near Folkestone.

Many beauty spots on the North Downs are owned by the National Trust such as Box Hill and Langdon Cliffs. Other areas of interest are Newland's Corner, St. Martha's Hill and Wye Downs. Much chalk grassland and ancient woodland on the downs is open access and there are also many historic sites on the downs such as Kit's Coty House near Maidstone and Dover Castle.

Sugarloaf Hill on the Folkestone Downs.	The North Downs at the Wye Downs National Nature Reserve.	The North Downs above Hollingbourne.	A dry valley on the dip slope of the North Downs near Hucking.
Woodland on the North Downs at the Hucking Estate.

• Geology of the United Kingdom
• Southern England Chalk Formation
• Chalk figures in the United Kingdom

• Brandon, P. (2005). The North Downs. Phillimore & Co. ISBN 1 86077 353 2

• KentDowns AONB site
• Surrey Hills AONB site