Hawthorn Dene is a

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 ...

in the

County Durham County Durham, officially simply Durham, is a ceremonial county in North East England.UK General Acts 1997 c. 23Lieutenancies Act 1997 Schedule 1(3). From legislation.gov.uk, retrieved 6 April 2022. The county borders Northumberland and Tyne an ...

district of

, England. The site occupies the incised valley of Hawthorn Burn and extends from just south of the village of Hawthorn eastward as far as the Durham Coast railway line: the area between the railway line and the sea forms part of the

Durham Coast The Durham Coast is a Site of Special Scientific Interest in County Durham, England. Starting just North of the River Tees estuary it extends, with a few interruptions, northward to the mouth of the River Tyne at South Shields. Notable location ...

SSSI. Much of the area consists of semi-natural and relatively undisturbed

woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...

that has developed on

Magnesian Limestone The Magnesian Limestone is a suite of carbonate rocks in north-east England dating from the Permian period. The outcrop stretches from Nottingham northwards through Yorkshire and into County Durham where it is exposed along the coast between Ha ...

; within Durham, only

Castle Eden Dene Castle Eden Dene is a Site of Special Scientific Interest and National Nature Reserve in the Easington district of County Durham, England. It is located mostly in Peterlee, between the A19 and A1086 roads. The dene is the largest, and biolog ...

SSSI has a larger area under this type of vegetation. At the eastern end of the dene, the woodland gives way to magnesian limestone grassland, while at the western end there is an area of tall fen vegetation. Much of the woodland is dominated by ash, ''

Fraxinus excelsior ''Fraxinus excelsior'', known as the ash, or European ash or common ash to distinguish it from other types of ash, is a flowering plant species in the olive family Oleaceae. It is native throughout mainland Europe east to the Caucasus and Alb ...

'', but in places wych elm, ''

Ulmus glabra ''Ulmus glabra'', the wych elm or Scots elm, has the widest range of the European elm species, from Ireland eastwards to the Ural Mountains, and from the Arctic Circle south to the mountains of the Peloponnese and Sicily, where the species reach ...

'' is dominant; such woodland is scarce in Durham. Another notable feature is the occurrence of yew, ''

Taxus baccata ''Taxus baccata'' is a species of evergreen tree in the family (botany), family Taxaceae, native to Western Europe, Central Europe and Southern Europe, as well as Northwest Africa, and parts of Southwest Asia.Rushforth, K. (1999). ''Trees of Bri ...

'', on the lower valley slopes, this being rare in Britain.

References

Sites of Special Scientific Interest in County Durham Nature reserves of the Durham Wildlife Trust {{Durham-geo-stub