Pig Hill is a Site of Special Scientific Interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 in the Easington

Easington (district)

Easington was, from 1974 to 2009, a local government district in eastern County Durham, England. It contained the settlements of Easington, Seaham, Peterlee, Murton, Horden, Blackhall, Wingate and Castle Eden...

 district of north-east County Durham

County Durham

County Durham is a ceremonial county and unitary district in north east England. The county town is Durham. The largest settlement in the ceremonial county is the town of Darlington...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, situated 1 km south of the village of Easington Lane

Easington Lane

Easington Lane is located in North East England between Houghton-le-Spring and Easington Village, in the parish of Hetton. It is the southernmost point of the City of Sunderland and Tyne and Wear....

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The steep hill slopes support an extensive area of primary magnesian limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 grassland in which blue moor-grass, Sesleria albicans, is abundant. The rich assemblage of grassland species includes a number of rare and local species, bird's-eye primrose, Primula farinosa

Primula farinosa

Primula farinosa, the bird's-eye primrose, is a small perennial plant in the family Primulaceae, native to northern Europe and northern Asia, and farther south at high altitudes in the mountains of southern Europe. This primrose thrives on grazed meadows rich in lime and moisture.-Growth:This...

, adder's-tongue fern, Ophioglossum vulgatum

Ophioglossum vulgatum

Ophioglossum vulgatum, commonly known as the Southern adderstongue, is a species of the plant genus Ophioglossum. It is native to temperate regions of the Northern Hemisphere, with a scattered distribution in Europe, Asia, northwestern Africa, and eastern North America.This plant grows from a...

, lesser club-moss, Selaginella selaginoides

Selaginella selaginoides

Selaginella selaginoides is a non-flowering plant of the spikemoss genus Selaginella with a wide distribution around the Northern Hemisphere. It resembles a moss in appearance but is a vascular plant belonging to the division Lycopodiophyta...

, and grass of Parnassus, Parnassia palustris

Parnassia palustris

Parnassia palustris, commonly called Marsh Grass-of-Parnassus, Northern Grass-of-Parnassus, and Bog-star, is a species of the genus Parnassia....

, as well as an inland colony of sea plantain, Plantago maritima

Plantago maritima

Plantago maritima is a species of Plantago, family Plantaginaceae. It has a subcosmopolitan distribution in temperate and Arctic regions, native to most of Europe, northwest Africa, northern and central Asia, northern North America, and southern South America...

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Notable among the fauna is the Durham Argus butterfly, Aricia artaxerxes salmacis, a form which is only found in the magnesian limestone areas of Durham.