Calstone and Cherhill Downs is a 128.6 hectare biological Site of Special Scientific Interest in Wiltshire, notified in 1971, including downland at Calstone Wellington and Cherhill. It provides one of the best examples in Wiltshire of unimproved downland.
Totternhoe Stone is a relatively hard chalk outcropping in the middle of the Lower Chalk in the Chiltern Hills in Hertfordshire, Buckinghamshire, Bedfordshire and Cambridgeshire, England. Geologically, it is located in the upper part of the Cenomanian stage of the Cretaceous.
Ingrebourne Marshes are a 74.8 hectare biological Site of Special Scientific Interest in Hornchurch in the London Borough of Havering. Ingrebourne Valley Local Nature Reserve includes a small part of the SSSI west of the River Ingrebourne. The site is managed by the Essex Wildlife Trust
Blow's Down is a 33.1-hectare (82-acre) biological Site of Special Scientific Interest in Dunstable in Bedfordshire. It was notified in 1989 under Section 28 of the Wildlife and Countryside Act 1981, and the local planning authority is Central Bedfordshire Council. The site forms around half of the 62.3-hectare (154-acre) Blow's Downs nature reserve, which is managed by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire.
Pegsdon Hills and Hoo Bit is a 79-hectare (200-acre) nature reserve in Pegsdon in Bedfordshire. It is managed by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire. The site is on the border between Bedfordshire and Hertfordshire, and it covers Pegsdon Hills and part of the adjacent Deacon Hill in Bedfordshire, and Hoo Bit in Hertfordshire. It is in the Chilterns Area of Outstanding Natural Beauty, and part of the site is designated by Natural England as the Deacon Hill SSSI.
Totternhoe Knolls is a 13.1-hectare (32-acre) Site of Special Scientific Interest (SSSI) in Totternhoe in Bedfordshire. It is also a local nature reserve, and part of the Chilterns Area of Outstanding Natural Beauty. The site is owned by Central Bedfordshire Council and leased to the National Trust. Most of the site is maintained jointly by the National Trust and the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire (WTBCN), and is part of the WTBCN Totternhoe nature reserve, which also includes Totternhoe Chalk Quarry and Totternhoe Stone Pit. The SSSI also includes Totternhoe Castle, the earthworks of a Norman motte-and-bailey castle which is a Scheduled monument.
Totternhoe Chalk Quarry is a 13.4-hectare (33-acre) biological Site of Special Scientific Interest in Totternhoe in Bedfordshire. Part of it lies in Totternhoe nature reserve, which is managed by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire. The site is part of the Chilterns Area of Outstanding Natural Beauty.
Deacon Hill SSSI is a 35.4-hectare (87-acre) biological Site of Special Scientific Interest in Pegsdon in Bedfordshire. It is in the Chilterns Area of Outstanding Natural Beauty, and it is part of the Pegsdon Hills and Hoo Bit nature reserve, managed by Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire.
Knocking Hoe is a 7.7 hectare National Nature Reserve and biological Site of Special Scientific Interest near Pegsdon in Bedfordshire. It is mentioned in A Nature Conservation Review. It is part of the Chilterns Area of Outstanding Natural Beauty, and is managed by Natural England.
Aston Rowant National Nature Reserve is located on the north-west escarpment of the Chiltern Hills, in the Chilterns Area of Outstanding Natural Beauty. It has an area of 159.1 hectares, and most of it is a 128.5 hectares biological Site of Special Scientific Interest. It is listed as a Grade 1 site in A Nature Conservation Review. The reserve is in several sections, mostly in the parish of Lewknor in Oxfordshire, with smaller sections in the parish of Stokenchurch in Buckinghamshire.
Pitstone Hill is a 22.9-hectare (57-acre) biological Site of Special Scientific Importance east of Pitstone in Buckinghamshire. It is in the Chilterns Area of Outstanding Natural Beauty, and is crossed by the Ridgeway National Trail.
Decoy Pit, Pools and Woods is a 17.7-hectare (44-acre) biological Site of Special Scientific Interest south of Aldermaston in Berkshire. An area of 8 hectares is a nature reserve called Decoy Heath, which is managed by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust.
Bacombe and Coombe Hills is a 76.4-hectare (189-acre) biological Site of Special Scientific Interest in Upper Bacombe in Buckinghamshire. Bacombe Hill was formerly owned by Buckinghamshire County Council, which transferred it to Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust in 2014. Coombe Hill is owned by the National Trust.
Houghton Regis Marl Lakes is a 20.1-hectare (50-acre) biological Site of Special Scientific Interest in Houghton Regis in Bedfordshire. It was notified under the Wildlife and Countryside Act 1981 in 1988.
Kensworth Chalk Quarry is a 131.3-hectare (324-acre) geological Site of Special Scientific Interest in Kensworth in Bedfordshire. It was notified under Section 28 of the Wildlife and Countryside Act 1981, and the local planning authority is Central Bedfordshire.
Smithcombe, Sharpenhoe and Sundon Hills is an 86.1-hectare (213-acre) Site of Special Scientific Interest in Sharpenhoe in Bedfordshire. Most of it is a National Trust property comprising Sundon Hills, Moleskin and Markham Hills, Sharpenhoe Clappers and Smithcombe Hills. It is part of the Chilterns Area of Outstanding Natural Beauty, and Sharpenhoe Clappers is protected as a Scheduled Ancient Monument.
Totternhoe nature reserve is managed by the Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire (WTBCN). The 31-hectare (77-acre) site is in Totternhoe in Bedfordshire, and it includes parts of three Sites of Special Scientific Interest (SSSIs). Totternhoe Knolls is a biological SSSI owned by Central Bedfordshire Council and leased to the National Trust. Most of it is managed jointly by the National Trust and the WTBCN, excluding Totternhoe Castle, the earthworks of a Norman motte-and-bailey castle which is part of the SSSI but not of WTBCN's nature reserve. Totternhoe nature reserve also includes the geological SSSI, Totternhoe Stone Pit, which is not open to the public, and other areas owned by WTBCN, including part of Totternhoe Chalk Quarry, another biological SSSI.
Wormsley Chalk Banks are six separate areas which together are a 14.1-hectare (35-acre) biological Site of Special Scientific Interest near Turville in Buckinghamshire and Oxfordshire. The site is in the Chilterns Area of Outstanding Natural Beauty.
Glemsford Pits is a 37.5-hectare (93-acre) biological Site of Special Scientific Interest south of Glemsford in Suffolk. The River Stour, which forms the boundary between Suffolk and Essex, runs through the site, which is thus in both counties.
