Area: 158.5 hectares.
Name changed from Dinas Head and Constantine Bay due to extension of site. Within the Cornwall AONB. Part of this site is within the Trevose Head Heritage Coast. The Geological SSSI, Dinas Head to Trevose Head is included within this site.
Description and Reasons for Notification:
This coastal site lies c. 7km to the west of Padstow. The southern part of the site comprises a large sand dune system backed by an area of dune grassland. The northern part is underlain by calcareous Devonian Slates supporting a coastal fringe of maritime grassland. In addition, more acidic soils to the east of the Trevose Lighthouse, support an area of maritime heathland. Dinas Head to Trevose Head is a site of great geological importance. This is a classic area for the development of sodium metasomatized sediments (adinoles and spilosites) adjacent to basic intrusives, not only in Cornwall, but the U.K. Apart from the large zone of variably metasomatized sediments, there is good evidence to indicate that the related (now mildly metamorphosed) sill-like greenstone body was intruded at a high level into wet sediments. This provides a basis for interpreting the metasomatism of the adjacent sediments as due to seawater trapped in pore spaces.
At the seaward side of the dune system strandline colonising vegetation includes sea rocket Cakile maritima and fosted orache Atriplex laciniata, a species of very local distribution in Cornwall. The stable dunes are dominated by marram grass Amnophila arenaria with abundant sea bindweed Calystegia soldanella, wild carrot Daucus carota and kidney vetch Anthyllis vulneraria and occasionally lady’s bedstraw Galium verum. Uncommon species such as pyramidal orchid Anacamptis pyramidalis and sea holly Eryngium maritimum are present together with the nationally rare portland spurge Euphorbia portlandica.
The dune grassland supports a very rich flora with some notable rarities. The sward is dominated by red fescue Festuca rubra, with ferngrass Desmazeria rigida, and sea ferngrass D. marina. Thyme Thymus polytrichus, eyebright Euphrasia offinalis agg., and hairy bird’s-foot-trefoil Lotus hispidus, are common as is the parasitic dodder, Cuscuta epithymum. Of great importance is the presence of a thriving population of the rare hairy-fruited cornsalad Valerianella eriocarpa. The dune fescue Vulpia membranacea, a national rarity, occurs here as does the locally distributed yellow horned poppy Glaucium flavum.
Red fescue dominates the maritime grassland bordering the cliffs of Dinas Head. Thrift Armeria maritima, rock samphire Crithmum maritimum, betony Stachys officinalis and the prostrate form of dyer’s greenweed Genista tinctoria are among an outstanding flora. The cliffs support the national rarities rock sea-lavender Limonium binervosum, tree mallow Laverta arborea and golden samphire Inula crithmoides. Of particular interest is the presence of strong colonies of the rare wild asparagus Asparagus officinalis and shore dock Rumex rupestris.
In addition, there is a wet flush with a rich marsh flora made particularly noteworthy by the presence of Juncus foliosus, one of the toad rush aggregate, and a species of very restricted occurrence in Cornwall. The maritime heathland is not extensive on this site but forms an important community, dominated by heather Calluna vulgaris, and bell heather Erica cinerea with scattered gorse, Ulex europaeus. A small area of interesting herb-rich unimproved hay meadow lies to the north of the golf course.
The coastal cliffs around Dinas Head provide important sites for a number of breeding seabirds including fulmar Fulmaris glacialis, razorbill Alca tora and guillemots Uria salge. The sand dunes of Constantine Bay support an increasing population of the white sandhill snail Theba pisana. This is thought to be the only known site in England for this species.