Sites of Special Scientific Interest in London

Harefield Pit is a 1.8-hectare geological Site of Special Scientific Interest in Harefield in the London Borough of Hillingdon. It occupies much of a partially filled-in chalk quarry. It has two entries in the Geological Conservation Review database.

Abbey Wood is a 6.3-hectare (16-acre) geological Site of Special Scientific Interest in Abbey Wood in the London Borough of Bexley. It is located in Lesnes Abbey Woods south-east of the ruins of Lesnes Abbey. Members of the public can dig for fossils in a small area designated as the Fossil Bed with the permission of the Lesnes Abbey ranger.

Saltbox Hill is a 22.2 biological Site of Special Scientific Interest in three separate areas in Biggin Hill in the London Borough of Bromley. One area of 6.9 hectares is owned and managed by the London Wildlife Trust. It is also a Site of Metropolitan Importance. It is a steeply sloping 55 acre biological site, which is close to Charles Darwin's home, Down House, and inspired him and provided him with a picnic place.

Rainham Marshes is an RSPB nature reserve in the east of London, adjacent to the Thames Estuary in Purfleet, Thurrock and the London Borough of Havering.

Riddlesdown Common or Riddlesdown is a 43 hectare area of green space in Kenley, towards the northern end of the North Downs in the London Borough of Croydon. It is owned and maintained by the City of London Corporation, apart from two small areas, one of which is operated by the London Wildlife Trust and the other by Croydon Council. An area of 32 hectares is a biological Site of Special Scientific Interest. The name Riddlesdown also applies to the local district of residential housing. A trig point at the site indicates that it is 525 ft (160 m) above sea level.

Ruxley Gravel Pits is an 18.7-hectare (46-acre) biological Site of Special Scientific Interest in Ruxley, Orpington, in the London Borough of Bromley, and originally dug between 1929 and 1951. It is also a Site of Metropolitan Importance for Nature Conservation. It is owned by the Environment Agency and managed by Kent Wildlife Trust. Natural England has assessed its condition as "unfavourable recovering".

Gilbert's Pit is a 5.2-hectare (13-acre) geological Site of Special Scientific Interest in Charlton in the Royal Borough of Greenwich. It was notified in 1985 and was formerly known as Charlton Sand Pit. It is a Geological Conservation Review site. It is also part of the Maryon Wilson Park and Gilbert's Pit Local Nature Reserve. It adjoins Maryon Park and is close to Maryon Wilson Park.

Harrow Weald SSSI is a 3.7 hectare (9 acre) geological Site of Special Scientific Interest in Harrow Weald in the London Borough of Harrow. It was formerly part of the Stanmore and Harrow Weald Commons and Bentley Priory SSSI. It is a Geological Conservation Review site.

Hornchurch Cutting is a 0.8-hectare (2.0-acre) geological Site of Special Scientific Interest in Hornchurch in the London Borough of Havering. It is also a Geological Conservation Review site.

Mid Colne Valley is a 132 hectare biological Site of Special Scientific Interest in Harefield in the London Borough of Hillingdon and Denham in South Buckinghamshire. Its main importance lies in its extensive diversity of birdlife in lakes in former gravel pits.