Greensand Ridge

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For Greensand Ridge in Bedfordshire, see Bedfordshire#Geography.

The Greensand Ridge is the name given to the sandstone ridge running through Hampshire, Surrey and Kent.

Geological map of south-east England

Geological cross section of Kent, showing how it relates to major towns

It is a part of a series of ridges running from west to east across the south east England. These ridges are the remains of the Wealden dome, a denuded anticline, which was the result of uplifting caused by the Alpine movements between 10-20 million years ago. The dome was formed of an upper layer of chalk above subsequent layers of upper greensand, upper clay, lower greensand, lower clay and red sandstone. The top of the dome eventually eroded away through weathering. The ridges and valleys were caused by clay eroding at a faster rate than the exposed chalk, greensand and red sandstone.^[1]

Greensand is a calcareous sandstone containing an uneven distribution of the mineral glauconite, giving the sandstone a greenish tinge. On exposure to the air this oxidises into a yellow stain.^[1]

Greensand comes in four layers: the Folkestone Beds 60-250 ft thick; The Sandgate Beds 5-120 ft thick; the Hythe beds 60-350 ft thick and Atherfield Clays 15-50 ft thick.^[2] The soil of the greensand is quite varied, ranging from fertile to fairly sterile. On the fertile soils we see chestnut and stands of hazel and oak, while Scots Pine and Birch colonise the poorer soils.^[1]

Principal settlements include Petersfield (at the western end), Godalming, Reigate, Oxted and Sevenoaks. The eastern end of the ridge forms the northern boundary of the Romney Marshes. Much of the ridge in Surrey and Kent is followed by the Greensand Way. It reaches its highest elevation (294 metres) at Leith Hill in Surrey.

[edit] References

^ ^a ^b ^c Greensand Way in Kent, 1992, Kent Count Council, ISBN 1-873010-23-0
^ Britain's Structure and Scenery, L.Dudley Stamp., Pub Sept 1946, Collins New Naturalist Series.