Essex is a county in the east of England. In the early Anglo-Saxon period it was the Kingdom of the East Saxons, but it gradually came under the control of more powerful kingdoms, and in the ninth century it became part of Wessex. The modern county is bounded by Suffolk and Cambridgeshire to the north, Hertfordshire to the west, Greater London to the south-west, Kent across the River Thames to the south, and the North Sea to the east. It has an area of , with a coastline of , and a population according to the 2011 census of 1,393,600. At the top level of local government are Essex County Council and two unitary authorities, Southend-on-Sea and Thurrock. Under the county council, there are twelve district and borough councils.

In England, Sites of Special Scientific Interest (SSSIs) are designated by Natural England, which is responsible for protecting England's natural environment. Designation as an SSSI gives legal protection to the most important wildlife and geological sites. As of August 2016, there are 86 sites designated in Essex. There are 19 sites with a purely geological interest, and 64 listed for biological interest. A further three sites are designated for both reasons.

The largest is Foulness, which is internationally important for wildfowl and waders, and has 71 nationally rare invertebrate species. The smallest is Holland-on-Sea Cliff, a geological site which throws light on the course of the River Thames before it was diverted south by the Anglian glaciation around 450,000 years ago. Hangman's Wood and Deneholes has deneholes, shafts created by medieval chalk mining which are now used by hibernating bats. Lion Pit is the site of flint-knapping by Neanderthals around 200,000 years ago, and it has been possible to fit back together some of the flint flakes.

Key

Interest

B = site of biological interest G = site of geological interest

Public access FP = access to footpaths through the site only NO = no public access to site PP = public access to part of site YES = public access to site

Other classifications BSO = Bird Sanctuary Order Buglife = Buglife – The Invertebrate Conservation Trust DVAONB = Dedham Vale Area of Outstanding Natural Beauty

EWT = Essex Wildlife Trust GCR = Geological Conservation Review HMWT = Herts and Middlesex Wildlife Trust LNR = Local Nature Reserve NCR = Nature Conservation Review site NNR = National Nature Reserve NT = National Trust Ramsar = Ramsar site RSPB = Royal Society for the Protection of Birds SAC = Special Area of Conservation SAONB = Suffolk Coast and Heaths Area of Outstanding Natural Beauty SM = Scheduled Monument SPA = Special Protection Area

Sites