Langham Pond is a biological

Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain, or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland, is a conservation designation denoting a protected area in the United Kingdom and Isle ...

north of

Egham Egham ( ) is a town in the Borough of Runnymede in Surrey, England, approximately west of central London. First settled in the Bronze Age, the town was under the control of Chertsey Abbey for much of the Middle Ages. In 1215, Magna Carta was ...

Surrey Surrey () is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Greater London to the northeast, Kent to the east, East Sussex, East and West Sussex to the south, and Hampshire and Berkshire to the wes ...

. The pond and its surrounding

alluvial Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

meadows on chalk represent a habitat unique in southern England. The pond is the remains of an

oxbow lake An oxbow lake is a U-shaped lake or stream pool, pool that forms when a wide meander of a river is meander cutoff, cut off, creating a free-standing body of water. The word "oxbow" can also refer to a U-shaped bend in a river or stream, whether ...

, formed when a meander of the

River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, s ...

was bypassed. The pond contains all four British

duckweed Lemnoideae is a subfamily of flowering aquatic plants, known as duckweeds, water lentils, or water lenses. They float on or just beneath the surface of still or slow-moving bodies of fresh water and wetlands. Also known as bayroot, they arose fr ...

s, three nationally scarce plants and a species of fly which has been found nowhere else in Britain, '' Cerodontha ornata''.

References

External links

Surrey County Council map of SSSIs
{{SSSIs Surrey Sites of Special Scientific Interest in Surrey