Strumble Head - Llechdafad Cliffs

Also within

Dyfed County Arfordir Penfro / Pembrokeshire Coast National Park

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Habitats

Bracken scrub

Geology & landscape

Geological Period: Ordovician

Landscape processes: Coastal, Volcanic / Igneous

Birds & fish recorded

Birds

Fish

Description

Description Geological The sea cliffs around Strumble Head provide sections through the vast thickness of volcanic lavas and associated rocks which accumulated here during Lower Ordovician times, some 460 million years ago. During this period of crustal instability a number of volcanoes were active in Wales, but Strumble Head is of particular interest since much of the volcanic activity took place under the sea. The exposures within the site demonstrate the character of a major Lower Ordovician volcanic episode and contain a most illustrative section through a vast pillow lava pile associated with minor sedimentary sequences and contemporaneous, high-level intrusive sheets. The site represents an important Llanvirn volcanic centre of the greatest research and educational value. Biological Strumble Head and the cliffs to the south are of the highest importance for seacliff vegetation. Dramatic vertical cliffs reach 140 metres in height. Lower bevelled cliffs are frequent and exhibit classic vegetation zonations related to exposure to strong, salt-laden winds. Several rare ‘Lusitanian’ higher plants and ferns occur in quantity, and maritime lichens are also noteworthy. Chough nest in high densities, and large feeding flocks are seen on the cliffs. There are also small colonies of seabirds. Seals breed in the caves and on the beaches of the many bays. Several notable invertebrate species occur. The geologically complex coastline is much indented, and has all aspects from north to south. The most seaward slopes support crevice communities, with thrift Armeria maritima and rock samphire Crithmum maritimum, whilst many of the islets have bird-influenced vegetation of tree-mallow Malva arborea and sea beet Beta vulgaris subsp. maritima. Maritime grassland dominated by red fescue Festuca rubra, with scattered thrift, kidney vetch Anthyllis vulneraria and spring squill Scilla verna is widespread, but the extensive areas of maritime heath are the most striking features of the vegetation. Heather Calluna vulgaris, bell heather Erica cinerea, and western gorse Ulex gallii dominate the drier rocky slopes and knolls. Cross-leaved heath Erica tetralix and purple moor-grass Molinia caerulea are found where the heath merges into spring fed valley mires. Sea campion Silene uniflora, spring squill, common bird's-foot-trefoil Lotus corniculatus and sea plantain Plantago maritima are abundant. Carline thistle Carlina vulgaris, saw-wort Serratula tinctoria, wild thyme Thymus praecox and burnet rose Rosa spinosissima are also present in the heath. Bracken Pteridium aquilinum and bluebell Hyacinthoides non-scripta, along with European gorse Ulex europaeus on shallow soils, dominate the more sheltered slopes. Numerous small springs and streams are present. Royal fern Osmunda regalis is frequent where these tumble over the cliffs. The flushes around the springs and seepages have a rich flora which merges with heath and maritime or acidic grassland in places. cowslip Primula veris and early-purple orchid Orchis mascula are a feature of these habitat mosaics. Most of the numerous rare higher plants are found in the heathland and associated flushes. These include large populations of the rare hairy greenweed Genista pilosa and pale dog-violet Viola lactea. The spiked speedwell Veronica spicata subsp. hybrida also flourishes on rocky ledges and open areas in the heath, at its only known location in West Wales. Open areas (maintained by grazing and livestock trampling) in the flushes of Porthsychan and Pwll Arian have several other ‘Lusitanian’ species, including wavy St. John’s-wort Hypericum undulatum and the annuals, yellow centaury Cicendia filiformis and yellow bartsia Parentucellia viscosa. The scarce south-western fern, lanceolate spleenwort Asplenium obovatum grows on the ledges of Dinas Mawr. Notable lichens include the pollution-sensitive beard lichen Usnea articulata, which grows on hawthorn at Porthsychan, and Parmelia britannica and P. crinita occurring on sheltered rock outcrops. Cliff nesting birds in 1987 included several pairs of chough, 8 small razorbill colonies with some 140 birds, and 2 small guillemot colonies with at least 50 birds. There were also 100 pairs of fulmar, 346 pairs of herring gull, 8 pairs of great black-backed gull and 4 pairs of lesser black-backed gull. Other breeding birds include buzzard, raven, wheatear, stonechat, rock pipit and whitethroat. Palmate newt, toad, frog, lizard and adder occur. Grey seals Halichoerus grypus breed on the beaches and in the caves, with about 50 pups born each year. Twenty species of butterfly have been recorded, including a small colony of the small blue Cupido minimus and abundant grayling Hipparchia semele. Other scarce invertebrates include the tortoise beetle Pilemostoma fastuosum and two flies Paragus haemorrhous and Epitriptus cingulatus. Remarks: The site is within the Pembrokeshire Coast National Park.

Species mentioned

Plant communities