Heathland sites in SurreyIn Surrey, heathland is largely confined to two Natural Areas: the London Basin (on Tertiary sands and gravels overlying the London Clay) in the north west of the county and the Wealden Greensand in the south west and centre. Additionally, there is some heathland (notably Headley Heath) on superficial gravels overlying the chalk in the North Downs Natural Area.a) London Basin Natural AreaAlong with contiguous heathland in Hampshire and Berkshire, heathland in this part of Surrey is generally referred to as belonging to the ‘Thames Basin’ rather than ‘London Basin’. Approximately two thirds (about 2,000 hectares) of the county’s surviving heathland lies in the Thames Basin, forming a discontinuous band of sites from Epsom, Esher and Oxshott Commons in the east, westwards to the Hampshire border. Heathland has developed here on the Bagshot, Barton and Bracklesham Beds, Tertiary deposits mostly of sands and gravels with some clays. The topography of these heaths is generally gentle and there are large areas of low lying land supporting humid and wet heathland although, in places, steep hills support dry heath. Three sites, Ash Ranges, Pirbright Ranges and Chobham Common, account for three quarters of the heathland in the Thames Basin; nevertheless other smaller sites have considerable importance in maintaining biodiversity across the range of heathland within the Natural Area. b) Wealden Greensand Natural Area
c) North Downs Natural AreaIn a very few places, superficial deposits over the chalk of the North Downs support heathland. The largest example is Headley Heath where the more ‘typical’ acidic heathland plant communities are accompanied by small areas of ‘chalk heath’ that are interesting mixtures of chalk downland and heathland species. There are probably no more than 20 hectares of heathland over the chalk. |