Calstone and Cherhill Downs (grid referenceSU047692) is a 128.6hectarebiological Site of Special Scientific Interest inWiltshire,notified in 1971, includingdownland atCalstone Wellington andCherhill. It provides one of the best examples in Wiltshire of unimproved downland.[1]
The site forms part of theNorth Wessex Downs Area of Outstanding Natural Beauty. The site lies towards the western edge of theMarlborough Downs, has a narrow plateau of the Middle and Upper Chalk and descends steeply to the north and more gently to the south. The south-facing slope has a complex structure of narrow, steep-sided dry valleys and coombes and has a mixture of grasses, sedges andforbs. Here grow a typical calcareous community includingglaucus sedge,sheep’s-fescue,meadow oat-grass,heath-grass andcommon quaking-grass, together withcowslip,salad burnet,rock-rose,betony,field fleawort,bastard-toadflax,round-headed rampion,small scabious,devil’s-bit scabious,horseshoe vetch,kidney vetch andchalk milkwort. Orchids found here include,early purple orchid,burnt orchid,fragrant orchid,bee orchid andfrog orchid, the last three all being common here.[1]
The site is also excellent for invertebrates, hosting thesmall blue,chalkhill blue,Duke of Burgundy andmarsh fritillary, as well as the rarewart-biter bush cricket and the uncommon bugSehirus dubius The lime-loving heath snailHelicella itala is also found here. There is adewpond that holds water all year round; newts are found here as well as theEmperor dragonfly and the azure damselflyCoenagrion puella.[1]
51°25′18″N1°56′02″W / 51.42179°N 1.93380°W /51.42179; -1.93380