Croham Hurst

Croham Hurst is a 33.6 hectare (83.02 acre) biological Site of Special Scientific Interest (SSSI) and a Site of Metropolitan Importance for Nature Conservation in South Croydon in the London Borough of Croydon. Its SSSI designation is due to its importance for nature conservation, but it is also a Regionally Important Geological Site. The site is a steep hill, which is ancient woodland, although there are few very old trees because until the railways made cheap coal available, the timber was used for fuel. On the lower slopes there is a diverse community of plants dominated by oak and hazel on rich soils overlying chalk. Further up the trees are mainly beech on Thanet Sands, and towards the top the main trees are oak and birch on the acidic Blackheath pebble beds. The Thanet Sands have eroded, but the Blackheath beds are bound by a natural cement, and this has resisted erosion to make a natural cap to the hill. The top is mainly bare of trees, with rounded pebbles made when the area was the base of shallow seas in the Eocene epoch around 50 million years ago. The sparse vegetation at the top is mainly wavy hair-grass, heather and bilberry.