North Downs

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Geology of the South East, Chalk is light green (6)

The steep scarp slope of the North Downs above Folkestone. The conical hill in the distance is Summerhouse Hill.

The North Downs in England is a ridge of chalk hills that stretches about 100 miles (160 km) from Hampshire through Surrey (where for part of their course they are known as the Hog's Back) and Kent. The hills are cut by the Wey, Mole, Darent, Medway, and Stour rivers and form the northern part of the Wealden dome, of which the South Downs are their mirror image. They rise to 965 ft (294 m) at Leith Hill, south of Dorking in Surrey; the highest point in Kent is the top of Westerham Hill: 824 ft (252m).

Due to the porous nature of the underlying chalk, the North Downs is generally a treeless landscape. The scarp face on its southern side is the well-known aspect: the face is often cut by coombes, where woodland does appear; on the back slope there are the dry valleys typical of such landscape, in which are many small villages and winding lanes.

The North Downs have been designated as having two Areas of outstanding Natural Beauty (AONBs) - The Surrey Hills and Kent Downs. The North Downs Way often follows the Pilgrims' Way along the foot of the scarp.

Such areas are often referred to as Downland. Their main feature is that they are predominantly grassland, which in earlier times provided good grazing for sheep. Two breeds are called South Down and Hampshire Down as a result, although both once cropped the North Downs. Their constant eating of the grass kept down the scrub; the fact that few sheep now occupy the North Downs, and the myxomatosis outbreak in 1953 which led to fall in the rabbit population, means that there is more scrubland on the Downs than hitherto. However, rabbits have increased in numbers during the last few years, but too recently to have made a great difference to the formation of scrubland.