Sheepland Coast ASSI

The area is of special scientific interest because of its coastal flora and fauna and earth science features. Sheepland Coast is a rocky coastline in County Down, with cliff vegetation and other grassland communities. It includes pockets of saltmarsh and strandline along sheltered inlets.

The rock exposures along the Sheepland Coast are exceptional, providing much detail of the important geology of the area. The exposures are composed of Lower Palaeozoic sedimentary rocks of deep marine facies, strongly folded, faulted and weakly metamorphosed. The main rock types are thinly bedded, fine–grained sandstones and siltstones of the Hawick Group. These are Silurian sedimentary rocks of approximately 395 million years old and are part of the Scottish Southern Uplands/Irish Down-Longford Terrane, which records the closure of the Iapetus Ocean during the Caledonian Orogeny. A terrane is a geological unit, discrete in terms of structure and age, and distinct from adjoining areas.

Since 1977, the terrane has attracted international interest because of its interpretation as an accretionary prism. There is ongoing debate concerning the geographical position of the sediments which now form the rocks of this region, namely whether they were fore-arc or back-arc sediments. Irrespective of this, sediments were accreted on the north-western, Laurentian, shore of the Iapetus Ocean during plate collision and ocean closure. The unresolved argument between proponents of these rival hypotheses is critical to understanding of the British and Irish Caledonides.

Numerous fold axes are displayed in the rocks along the section from Ballyhornan to St Patrick’s Well. An excellent example of sole markings is found on an exposure at Port Rusley.

Biological interest is associated with the intertidal communities and the unusual range of habitats from splash zone, saltmarsh and strandline vegetation to maritime grassland, maritime heath and fen. This has resulted in a diverse range of plant communities.
The rocks at Sheepland coast have an extensive splash zone with a well-developed zonation of characteristic maritime lichens. Areas of saltmarsh and shingle beaches have developed in sheltered bays and inlets along the length of the coast. The saltmarsh consists of a matrix of sea-milkwort, common saltmarsh-grass, tall clumps of red fescue and saltmarsh rush.  sea plantain and common couch occur less frequently. Small areas of strandline occur behind the saltmarsh and shingle beaches and are generally dominated by sea beet, silverweed, common scurvygrass and curled dock.

Maritime communities along Sheepland Coast extend inland from the shore. A diverse range of grassland communities are part of a sequence which has developed in relation to decreasing maritime influence on moving inland. These communities begin just behind the shoreline, with grassland developing on very shallow soils in crevices and hollows amongst lichen-covered rocks, where skeletal mixtures of mineral and organic matter have accumulated. This grassland type also occurs around rock outcrops where deeper soils thin out. The vegetation comprises sea fern-grass along the shore, with species such as thrift, buck’s-horn plantain, red fescue, sea mouse-ear both species of hair-grasses (silver hair-grass and early hair-grass) and stonecrops (English stonecrop and biting stonecrop) throughout.

Further inland on the cliffs and slopes, ungrazed grassland is dominated by red fescue, Yorkshire-fog and Yarrow, with high frequencies of species such as smooth meadow-grass, cock’s-foot and glaucous sedge. Where grazing occurs a distinctive terracing on the slopes is created, which helps to maintain a very species-rich, open sward. This open grassland contains plants such as spring-sedge, wild thyme, red fescue, field wood-rush, common bird’s-foot-trefoil, bulbous buttercup, lady’s bedstraw and sea campion. There is great diversity of species on the slopes with distinctive colourful plants such as spring squill, common spotted-orchid, primrose and kidney vetch.

Further interest on the steeper slopes is added by flushing with base-rich waters, which has created distinctive wetland vegetation with purple moor-grass, common butterwort, few-flowered spike-rush, bog pimpernel and marsh arrowgrass.

Maritime heath has developed in combination with the grassland communities where there are particularly rocky outcrops, banks and steep slopes. On slightly deeper soils, small, scattered stands of heath with heather and western gorse occur. Where soils are thinner, the heathland communities are dominated by heather, bell heather, spring squill, common birds-foot-trefoil, thrift and ribwort plantain. Most notably, rock sea-lavender, which is endemic to Ireland and Great Britain, occurs here, its only known site in Northern Ireland. Rock sea-lavender is the only Northern Ireland member of a group of closely-related species referred to collectively as the rock sea-lavender aggregate or group. It is a UK priority species of maritime cliff and is protected under the Wildlife (NI) Order 1985.

Behind the slopes the habitat has less maritime influence and grades into species-rich neutral grassland, characteristic of lowland meadows. These grasslands are dominated by fine-leaved grasses with high herb and sedge cover. Distinctive species amongst the sward include red fescue and sweet vernal-grass, with glaucous sedge, spring-sedge, Burnet-saxifrage, pignut, bluebell, common knapweed, spring squill and Devil’s-bit scabious.

Additional interest is provided by a small base-rich fen within the townland of Newtown. The area represents an extended basin with gently undulating valley sides, and although much of it is comprised of swamp vegetation dominated by common reed, calcium-rich ground waters feed into the wetland along its northern edge. Consequently, Newtown fen represents one of the most easterly examples of base-rich fen in County Down. The area supports many wetland species, including stoneworts and a variable sedge component dominated by brown sedge and bottle sedge, with the notable lesser tussock-sedge also occurring. Blunt-flowered rush is locally dominant where peaty soils are flushed by base-rich waters. Associated higher plants with a widespread occurrence include bogbean, wild Angelica, and water mint. Additional species with a more localised occurrence include marsh cinquefoil, meadowsweet, ragged-Robin and the more notable brookweed. A dense mat of brown mosses dominated by pointed spear-moss grows beneath the sedge and herb sward. Other mosses include marsh bryum and scarcer giant spear-moss.

Sheepland Coast is also notable for the Wall butterfly. Historically, this species has been found fairly widely across Northern Ireland, but it has undergone a severe decline in the last 20 years. By 2001 the only known populations remaining were on the Down coast. The species is a colonial species found in open habitats with sparse vegetation and bare ground. They choose food plants growing along a vertical edge, such as a wall, in warm, sheltered locations. The commonest food plants are tall grasses such as cock's-foot, Yorkshire-fog, sheep's-fescue and wavy hair-grass.

Site Related Documents

Site map (.PDF 786Kb), Citation document (.PDF 217Kb) and Views about Management document (.PDF 70Kb).